TCM to ECU communication issues t444e/Allison 2000

[Flipmode]

CadillacKid, that’s useful information on the inhibit modes and I’ll definitely bring it up to the mechanic… prob just have him read your post so I don’t misinterpret it.

Ewo1, so I only tested the backbone from the diagnostic plug. From Can(+) to Can(-) or D to C, I got about 62 ohms with my Klein meter.

For voltage check from ground(A): I got 12.6v to B, 2.6v to C(Can+), and 2.4v to D (Can-).

For shits and giggles I pulled the resistor next to the trans and measured that which gave me 118 ohms. I didn’t bother checking the one under the hood as I had house chores to finish and it was dark. So those are the results that make me think my backbone is ok.

I will admit I’ve pulled the gauges a few times already and even ran the bus with the gauges unhooked but haven’t pulled the gauge circuit board to check the pins. I had figured that as the gauges were only working intermittently before anyway, just unhooking them would negate any detrimental repair I may have made on the cluster. I was under the impression the gauges wouldn’t have an effect on the TCM aside from the check trans light. I will check it tomorrow or Saturday. I’m going to feel real silly if I’m misguided and overlooked that obvious variable is my problem…

One of the other obvious variables that keeps popping up for me is the oil in the main trans plug to the internal harness. The other day right before I drove it, was the third time I unplugged it, washed out both sides with contact cleaner(first two times were with brake cleaner), and blew it out with compressed air. While I was under the bus this evening I pulled that plug and found some oil in it again. So whether related to the current issue or not I need to address that at some point. Combine that with the issue of my trans temp reading 320*f at startup makes me think pulling the pan may be a logical course of action. I’ve just figured reading the codes first would be logical in case there were other issues such as stuck solenoids. So I’ve looked a little into that remedy of changing the internal harness and it doesn’t seem like too bad of a project. I had the trans fluid tested a year ago and it came back good with no excessive wear but was deemed about through its midlife so changing the fluid would be a bonus.

I’m at the point where I realize I haven’t exhausted all the diagnostics that I can try but reading the TCM codes might keep me from chasing my tail going forward. I’ll definitely keep this tread updated as I go on.

Thank you all for the input

[cadillackid]

fluid in the trans cxonnector is definitely a concern.. and ive seen it cause issues.. usually more with speed sned temp sensors than with solenoids.. trans fluid generally in and of itself isnt conductive, however clutch material, and yes metal from normal wear can and does mix with trans fluid over time so it can become somewhat conductive...


I used to watch a youtube channel called precision transmission (before they went through family BS).. and fluid in the connector was often a cuase of wierd trans operations or codes being set.. its definitely not normal to be there... there are different harnesses... you may need to call your IH dealer and act like you are buying it from there and simply get the part number so you can obtain the right one..



IH "should" have that as a service part.. if not then an allison dealer may need to be involved using the trans serial number.. (my IH dealer is also an allison dealer)...

[Flipmode]

I got pretty much ghosted by the mechanic that was supposed to come out to read the TCM. I stopped getting a response from him but my buddy, who hooked us up, said he lost his license(dui?) and claims he can’t reach me by phone or text… so after a week of trying to get in touch I’m moving on. I found an Allison/Detroit Diesel shop about an hour south of me that does mobile service calls. The said they’ll get with me next week on when they can come out.

So in the meantime I decided that I would chisel away at the other issues, starting with my only active code 222 intake air sensor malfunction. Upon pulling the sensor out to source a replacement, I noticed one of the female pins appeared to be flared out compared to the other. I went ahead and pulled the connector apart, tightened the tubular pin so it no longer had a gap on its seam, and reassembled it. Running the self test yielded me with a 111; no active codes

But my trans issues were still there and this time it wouldn’t go in ANY gear, every gear was lighting up the shift inhibit light. On my bluefire, my trans temp showed 3212*F, lol. So with the momentum of fixing a problem, I went ahead an called international for the internal wire harness and pressure switch assembly. I think the harness was about $109 and the pressure switch assembly was around $89 so I went ahead and ordered them. Also ordered the internal, external filters, and a new pan gasket. So should be around $350 for that stuff.

With the internal harness plug leaking I know that has to be fixed regardless if that’s contributing to my current TCM issues. Having the Trans temp going bonkers makes me think throwing a new pressure switch assembly(with temp sensor built in) on while I’m in there seems to make sense. I’ve been looking a little into changing out the harness and pressure switch and it looks like I can do it right where it sits on the concrete driveway.

My thoughts now are should I attempt to do this repair before or after I have Allison out to read the codes? I didn’t ask what they figured would be the cost of a service call would be but would guess in the $200-500 range being the shop is about an hour away. So it seems that it might be worth doing the harness repair first with the hopes that is my culprit. Then maybe I won’t need Allison to come out. On the other hand, if there’s an issue with the solenoids or something along that line it would be easier to address that while I’m in there for the harness repair. …I think im leaning toward going ahead with the harness repair first and seeing what becomes of my current issues. I know I need that harness regardless so getting that variable out of the equation will atleast narrow down the focus points going forward if the problem persists. The icing on the cake is if it fixes everything and I do it all myself…one can only hope

[cadillackid]

If the connector is getting fluid in it then replace it and the internal harness. There’s a somewhat good shot that it will help or resolve your other issues.

It’s entirely possible that this triggers your inhibit Modes.

[ewo1]

Originally Posted by Flipmode

I got pretty much ghosted by the mechanic that was supposed to come out to read the TCM. I stopped getting a response from him but my buddy, who hooked us up, said he lost his license(dui?) and claims he can’t reach me by phone or text… so after a week of trying to get in touch I’m moving on. I found an Allison/Detroit Diesel shop about an hour south of me that does mobile service calls. The said they’ll get with me next week on when they can come out.

So in the meantime I decided that I would chisel away at the other issues, starting with my only active code 222 intake air sensor malfunction. Upon pulling the sensor out to source a replacement, I noticed one of the female pins appeared to be flared out compared to the other. I went ahead and pulled the connector apart, tightened the tubular pin so it no longer had a gap on its seam, and reassembled it. Running the self test yielded me with a 111; no active codes

But my trans issues were still there and this time it wouldn’t go in ANY gear, every gear was lighting up the shift inhibit light. On my bluefire, my trans temp showed 3212*F, lol. So with the momentum of fixing a problem, I went ahead an called international for the internal wire harness and pressure switch assembly. I think the harness was about $109 and the pressure switch assembly was around $89 so I went ahead and ordered them. Also ordered the internal, external filters, and a new pan gasket. So should be around $350 for that stuff.

With the internal harness plug leaking I know that has to be fixed regardless if that’s contributing to my current TCM issues. Having the Trans temp going bonkers makes me think throwing a new pressure switch assembly(with temp sensor built in) on while I’m in there seems to make sense. I’ve been looking a little into changing out the harness and pressure switch and it looks like I can do it right where it sits on the concrete driveway.

My thoughts now are should I attempt to do this repair before or after I have Allison out to read the codes? I didn’t ask what they figured would be the cost of a service call would be but would guess in the $200-500 range being the shop is about an hour away. So it seems that it might be worth doing the harness repair first with the hopes that is my culprit. Then maybe I won’t need Allison to come out. On the other hand, if there’s an issue with the solenoids or something along that line it would be easier to address that while I’m in there for the harness repair. …I think im leaning toward going ahead with the harness repair first and seeing what becomes of my current issues. I know I need that harness regardless so getting that variable out of the equation will atleast narrow down the focus points going forward if the problem persists. The icing on the cake is if it fixes everything and I do it all myself…one can only hope

As a low cost troubleshooting test, have you explored the possibility of switching out the TCM with a known good one???

Not saying yours is going bad but it would surely answer that question right quick !

[Flipmode]

Originally Posted by ewo1

As a low cost troubleshooting test, have you explored the possibility of switching out the TCM with a known good one???

Not saying yours is going bad but it would surely answer that question right quick !

No I haven’t. The only person that I know locally with a bus has a 545.

A bad TCM is definitely still on the list of possibilities which I figured would be pinpointed when Allison tried to read the codes. I think I am going to postpone Allison coming out until I change the harness being that needs to be done even if my shifting issues were resolved. International said the parts would be in Monday afternoon so hopefully I can get to it one evening this week and go from there.

I figure once I have parts in hand I’d drain the fluid out of the pan and let it sit a day before pulling the pan. Hopefully it’ll help on the residual dripping that I’ve seen people complain about. I haven’t looked into what new fluid I’d put back in but will prob just go with the conventional recommended fluid over synthetic.

[Flipmode]

So I got some results to report. Drained fluid, pulled the pan and found some metal pieces on the magnet. Brought them to my transmission guy/neighbor and he said it looks like part of a snap ring. Judging by the shape of the pieces, looks to be of a diameter greater than 4-6”; Im rough guessing for the clutches. I cut open the internal filter and it had a few pieces of metal but otherwise was IMO fairly clean. I’m really thinking the broken pieces somehow occurred when I last drove the bus troubleshooting these current issues. I’m pretty sure that was that clunk I heard as it wasn’t that loud but didn’t seem good at that time.

Transmission guy pretty much said if it’s going to be opened up it’ll be a full rebuild @$3500. In discussions with him, I realized I still am dealing with the original issue that I’m still not sure is TCM related or not. I’ve prepped myself for a rebuild but the thought of having to replace a TCM after the fact may put me over the edge on this project. I’ve decided that I’m not going to pursue pulling the tranny until I got a handle on the original issue. Might as well put the internal wire harness and pressure switch in to test that theory. I went ahead and threw the new internal filter on(as I cut the old one up) but just ran the old fluid through a paint strainer and put it back in.

I went ahead and tested the bus this evening just running it where it’s parked. With my bluefire connected, the trans temp read 76* at startup which is about ambient air temp currently. No check trans, engine, or shift inhibit lights when I put it in gear. It seemed to successfully shift into all gears and even showed the correct gear on the Bluefire dash. So it looks like a new internal harness and pressure valve assembly were the culprits. I guess I can’t be totally sure without driving it but that is the debate I’m currently having with myself.

So now I feel like I got a couple of paths I can go on:

1. Just send it- go ahead and drive it around, see what becomes of it. Lol, My short sighted frugal tendencies kinda want to go this route.If it ends up needing it, A rebuild is a rebuild…

2. Play it safe and pull the trans while there’s still hope of minimal carnage. Biting the bullet and realizing the tranny needs to be opened up gives me two more options that I’m seriously weighing:
2a. -$3500 minimum out of pocket to get it professionally rebuilt. Not sure if the snap ring caused any hard parts to break and if so how much more I’m going to spend.
2b. I’ve been watching a few good rebuild videos and reading some threads. The rebuild process initially looks a little daunting but the more I watch the more I want to try. I’m thinking that will be either a great decision or a magnificent failure. I really am excited to try to open up an Allison but have two thoughts on it:$3500 is a lot of money to shell out but being stranded far from home while on “vacation” is a feeble amount to have saved doing it myself.

I’m definitely open to hearing opinions on this situation and would love if someone that had experience working on Allisons to leave their $.02

[cadillackid]

KUDOS!! on the electronic issue!! good to make progress..


the snap ring.. ive seen transmissions run for a long time with busted snap rings.. ive also seen them die rather quickly... me being the one who doesnt want ot get stranded would probably have that bad boy on the ground in pieces... or at least have a shop examine it

[shortbus4x4]

It's always cheaper to schedule your repairs rather than having to do them when you're on a trip half way across the country.

[Flipmode]

Yeah, I’m feeling that piece of advice Shortbus. So I’m currently in elbow deep with my transmission. With the pieces of metal in the pan I just didn’t feel right trying to drive it at all. I pulled the trans where it sat(thankfully on my concrete driveway) and proceeded to pull it apart myself. There were a couple of interesting discoveries that really have me questioning if I want to see this rebuild through or bring it to someone with experience to make sense of it.

The main issue is the broken pieces of snap ring. Turns out those pieces I found are from the outer C4 spiral ring. To my eyes it appears to have spun and the leading end got hung up on the ribs causing it to buckle and break; but I’m not sure it’s possible as the two adjacent plates are interlocked to the ribs. The inner(thicker) snap ring in the same groove also was broken. It only had one break and does not appear to have spun. Both rings share the same groove in which the main case ribs are eaten up only about one half of the housing circumference, pretty much around the bottom where there’s a bigger gap between the ribs(oil drain or inspection hole?). Also, there is damage on the C4 side of the groove from the inner snap ring that from my guess was a force from the C5 piston engaged in some way. The edges of the ribs are broken/sheared off that makes it look like there’s a bevel on those ribs. Not sure if those forces from the C5 side of things are the cause or the effect; I’m still studying it but feel I’m throwing darts in the dark at this point.

The other interesting part of all this is that the filters and fluid appeared to be relatively clean for 100k miles. I have yet to find a resource to give specs on clutch thickness but they appear to have plenty of life if they’re not relatively new. I have a few hundred miles on this thing in the past 3 years. So in regards to the broken ring issue, was the trans messed with recently before my purchase and could the broken rings be an install error if the previous owner had the trans gone through?

Being the first transmission I’ve really opened up, I really don’t have a base line to judge without an outside reference or specs. I can source a good condition case on eBay for a decent price so rebuilding this thing is still within reason. If the clutches were to turn out to be fine then it would only need replacement for the case, the two snap rings and maybe the adjacent clutch plates, and a new gasket/seal kit. I’d think I’d still be under $1k doing it myself which is very appealing if the stars align….

[cadillackid]

to me that looks like a classic Bind.. whether you can re-use the case or not... a true transmission builder would probably say no.. others might say yes that a new spiral ring will keep the tension on the backing plate ring enough to be fine..



clearances are everything in an allison... as well as cleanliness (any trans). did the trans suffer some wierdness (perhaps metal i nthe valve body) which triggered the previous owners to replace the fluid and filters (obviously before the snap ring made its way to the pan...) or is this just a fairly clean transmission that suffered a bind up due to ??? (any number of things from computer to mechanical).


I would never consider emptying the case of the rotating assembly and not performing a full rebuild on that unit.. too many things to go wrong.. possibly not fixing what caused this failure.. and yep it could just plain be a snapring broke which allowed the spiral to get away and rattle around..



can you rebuild it yourself? sure you can if you are careful and have the tools and the necessary spare parts to make the clearances.. clearances are paramount because an allison is a clutch-clutch trans.. 3rd gen units didnt have near the learning abilities the 4th and 5th gen TCMs do so getting the mechanics right is important to avoid flares or binds..



a Huge part of being succesful in building transmissions is in being organized ..esp when it comes to the valve body.. there are Lots of things to go wrong in the valve body which break the rotating assembly .. lots of little springs and spacers and such..



ive never myself put together an allison 1000/2000 but have done others and took my time.. did it when others said you cant.. so I say go for it..



that said.. im suspect of that case... but it might run for 10 years no issue..

[Booyah45828]

I wouldn't try it. The old days you could do that because transmissions were largely mechanical and weren't clutch-clutch. To do it now, you need the scan tools and software in order to perform a reset and relearn. Being clutch-clutch like christopher said there is a relearn process we always perform anytime something internal is changed, that way the transmission shifts correctly. It will continually adapt every shift, but the relearn procedure makes it close

Installing a rebuild like that without reseting and relearning the adaptives opens yourself up to the ability of having issues like flaring, and slipping from late engagements, or grenading the thing altogether if 2 apply at the same time.

[Flipmode]

Originally Posted by Booyah45828

I wouldn't try it. The old days you could do that because transmissions were largely mechanical and weren't clutch-clutch. To do it now, you need the scan tools and software in order to perform a reset and relearn. Being clutch-clutch like christopher said there is a relearn process we always perform anytime something internal is changed, that way the transmission shifts correctly. It will continually adapt every shift, but the relearn procedure makes it close

Installing a rebuild like that without reseting and relearning the adaptives opens yourself up to the ability of having issues like flaring, and slipping from late engagements, or grenading the thing altogether if 2 apply at the same time.

Thank you Booyah for that input, it seems like a very valid point. For the sake of a discussion standpoint, it seems like an apples to oranges between yours and Christopher’s points of views as you’re referencing the install of a rebuilt trans vs his on the rebuilding of the trans itself. I agree, it is probably a good idea to have the TCM reset regardless of whether i rebuild it myself or have it rebuilt elsewhere. My understanding on what’s involved from an TCM standpoint is unclear; is that something I can have Allison come out and reset the TCM before I drive it or is it more involved with having the diagnostics hooked up for the actual driving/break in period? At this point, I’m kinda committed to reinstalling “a rebuilt transmission” in my driveway. Whether I do it myself or farm it out. Your comments make me realize getting the trans back into the bus is not necessarily the end of the rainbow to this story.

Your prospective highlights one of my biggest shortcomings from the beginning of these issues: lack of Allison diagnostic access. Hindsight, it was probably foolish of me to embark on this path without even pulling the trans codes. I had a few leads on transmission techs that ended up falling through before I ended up calling an Allison dealer directly. By that point I found the metal bits and figured I was probably due up to remove the trans either way so I canceled them coming out. My thought was after replacing the internal wire harness and having no more check trans light, the damage was done and the trans needed to be pulled. I will say despite being by far the heaviest, it was one of the easiest transmission removals I have done so I really am glad I didn’t pay a shop for that.



Christopher your point about every possible problem is on the table in respect to the rebuild definitely hits home. I know too well from other respects in life, you can’t call it good enough when you find the first obvious problem. I am curious on your definition of a full rebuild? I was planning on going through the whole transmission at minimum by replacing all the gaskets and seals. During that process any hard parts that were damaged would be replaced. I just ordered a replacement case (Allison 2400 with the same casting number 29536808 ) from one of this site’s members for $115 plus tax. Now, I was on the fence with the clutches but figured on keeping the clutch steels as long as they seemed ok. I would test the solenoids to the standards the ASTG manual puts out. I figured I’d check the clearances on the planetary set gears and obviously in the clutches as I assembled it. But I wasn’t planning on replacing all the bearings and even any thrust bearings that weren’t included with a seals and gasket kit as long as they seemed ok.

I’m putting the viability of doing this project myself on if I can keep the costs under about 1k-$1500. North of that the risk to reward seems to steer me to having a professional do it. I know my time is worth something but I do find merit in doing new/hard things so if I screw it up and I’m not out a bunch of money and I gain a bit of ‘experience’ I’m ok with that. The flip side to that is if I shell out the dough to have it professionally rebuilt and it still craps out due to issues Booyah pointed out; I think my bus project might be hard to financially justify to keep going. …but I guess if financial justification is my reasoning, I’m in the wrong hobby

[Flipmode]

On the subject of clutches, I went out and put the c4 piston and clutch pack back in. Even though that is where the groove is messed up, half of it is untouched. I put some feeler gauges at opposite sides just to keep it pretty even. The shorter feeler gauge is at .080 but is really tight. The longer set is at .070” but fits sloppy so I’d say it’s sitting pretty far north of the .040-.060” allocation range. I guess those clutches aren’t so new after all. I also checked the c3 clutches a got around .055 which is in the ballpark but I think new clutches are in order.

[cadillackid]

new clutches are a no brainer for me.. they are a wear item.. just like if I have a brake caliper stick and I feel it.. unless my pads are BRAND new.. I toss the pads and put on new...



resetting the Adapts needs to be donw before you drive it.. so the way allison adaptive learn works is using the speed sensors within the transmission.. (by looking at the input shaft speed and the output shaft speed) it "learns" how to best shift gears.. to eliminate Flares (think of shifting a manual and letting the RPM rev up before you let the clurtch back out again.. ) essentially the trans being in neutral(or another range) because the on-coming clutch was a bit slow to pull in..


it also works to eliminate Binds (oncoming clutch is too quick to start engagement ). essentially trying to put the transmission into an unsustainable position.. severe binds result in broken metal.. busted shafts.. ive seen it strip the teeth off of clutches or drums.. the expensive planets usually survive as long as metal doesnt turn gears into coffee grinders..


each time you start the vehicle, the transmission uses the last set of adapt strategies it had prior ro shutting it down. (adapts survive battery disconnect).



if you have as trans that has gotten weak.. maybe low line pressure so a call for a shift results in the apply piston coming on slow or the clearance is high so it takes more fluid (time) for the piston to make engagement pressure.. the computer adjust the timings and even how it operates the solenoids.. esp the trim solenoids.. so as a driver your experience remains good throughout the life of the transmission.


the old mechanical allisons used to start getting sloppy in their old age.. you could feel whenm a 545 or 643 esp was starting to wear.. it "just didnt shift like it did years ago"..


anyway now put that TCM used to a sloppy trans into a nice fresh tight new trans... and it applies the same strategies.. now all the sudden your C4 comes on really fast as you go into 2nd.. (your C5 is probably going to have words for you)..



how do you reset the adapts? if you have a Nexiq or Clone diuagnostic device.. there are "unofficial" versions of allison DOC around.. you turn the key on, engine off, and click the reset adapts button.. write the changes and done.



the 4th gen units have a Fast adapt process by which you put it in fast adapt mode, go out and floor ir from gears 1-4 at least 4 times


there is also a Parked Fastlearn process which is on later 4th gens ive never used it..

[Flipmode]

It’s been a bit but I’m back for an update. I need to apologize for the lengthy posts, I guess it’s beyond my ability to write brief posts. Even though I’m past this point I figure I’ll keep it in order. Rebuilt the trans using the case I bought and got a rebuild kit from Xcalliber transmissions with steels and clutches. The process was time consuming especially due to my limited time devotion but I got it done. I managed to keep the clearances pretty close. In case anyone was curious, here’s the clearances I ended up with vs ASTG specs:

C1 (should be .105-.115”) I got .102 reusing the old steels as the new ones put me around .095

C2 (should be .060-.085”) I got .083”

C3 (should be .040-.060) I got .063

C4 (should be .040-.060) I initially got a bit over .080” and unfortunately there’s no ‘selective’ plates for that clutch. If there was any point in the rebuild that I had regret it was then, as I had no good ideas on what to do. Talking with the guy at Xcalliber, he suggested to get an extra base plate as it is about .125” vs the .100” steels. Just cut the spring tabs off it and use it in place of one of the steels. That trick yielded me a final of .058” clearance. So that saved me from a lot of self doubt in this project…

C5 (should be .090-110”) This was a bit tricky as the tail shaft assembly holds it in place. I used a straightedge and tail end of a caliper to calculate the measurements of where it should be when fully assembled. I came up with .102”. After I assembled it I was able to check the actual clearance through an inspection hole and gauged about .100”. I felt pretty good at that point.

Went through the pump, valve body, and tested the solenoids. Changed out orings and seals. Nothing really stood out including the valve body filter which was all really clean. Does look like it had been gone through recently… Put it all back together and into the bus.

[Flipmode]

Figured I was looking pretty good and scheduled a service call from Allison/Detroit Diesel to reset the shifting on the TCM. The Palm Beach branch only does marine so I had to schedule through the Ft Lauderdale branch which is about 45 min south. I knew it was going to be expensive but didn’t ask specifics as they were the only shop I could find to do mobile visits. …Well, turns out I should have asked, as I could have bought a Nexiq instead

Up to the point Allison came I hadn’t even plugged in the TCM fuse just so any initial carnage could be witnessed through the diagnostics. We plugged it in and right away had electrical issues on Allison DOC. It was TCM voltage issues and stuff off the internal wire harness. The trans temp was intermittently working. I told the tech about it having a new harness, pressure switch, and having checked the power wiring to the TCM. We discussed the possibility of it being a bad TCM. He admitted that he hadn’t messed with the gen 3s much and even though they usually keep spare TCMs in stock for diagnostics, they don’t for the older models. His shop doesn’t even have the stuff to test them, they would have to send it down to their Miami shop.

In addition to the electrical issues, the shifting wasn’t quite right. When I hooked up the trans, I assumed the linkage wouldn’t need any adjustment. But the shifting was way off for some reason.

The tech cleared the codes and some came right back. We tried the wiggle test on the wire harness and such with no effect on the codes or the trans temp. By that point I realized that it would be cost prohibitive to have the tech go through all my issues so I just had him reset the shifting and sent him down the road.

The codes that showed up were:
P0562 System voltage low
P0711 Trans fluid temp sensor circuit performance
P0748 pressure control solenoid A electrical
P0778 pressure control solenoid B electrical
P0561 System voltage performance

So I set about testing as much as I could. Having done run/stop testing before I pulled the trans, I realized I never checked the batteries so they were atleast undercharged or bad. With Key on, engine off voltage was dropping into the 11s so I charged the batteries(after disconnecting the computer fuses). Batteries we’re able to get charged to 12.66v range at rest and around 12.4 key on. Alternator was producing 13.7-13.9v. I ohmed out the wire harness from the TCM to the other plugs, same for the internal harness, and it all checked out good each at less than .4 ohms. I did find a little oil in the trans plug but wasn’t sure if it was new or just from getting splashed on the rebuild. I washed it out with contact cleaner and filled it with die electric grease to hopefully protect it. I feel like I’ve checked most of the things I can with the exception of splicing the TCM power/ground wires straight to the battery to eliminate any power variables. I’m reluctant to start cutting into the main harness at the moment but may be my next step.

For the shifting issues, I found that the shifter arm that came with my “new” transmission case was different than my original one. I never gave much thought and figured they were the same. Well, turns out it’s shorter and the key way is clocked differently than the original one so I just put the other on and it shifts perfectly without adjusting. It’s a small win…

After all that I put it back together and find the problems are exactly where I started this thread, lol. The check trans light is on in the dash and I get shift inhibit in reverse.

I called Allison and talked to them about bench testing the TCM but it was explained to me that it’s not a definitive test whether it was good or bad. Their advice is check the other variables first.

Im tired of there being this mysterious veil in between me and the TCM. My original reluctance on buying the Nexiq is that I would still have to get Allison DOC which is crazy expensive. I don’t like that every clone is dropshipped from China so I think i might buy a Nexiq and look into acquiring DOC through other Chanels…worst case is I’ll atleast be able to run Navistar software on it.

[cadillackid]

DOC can definitely be had through other channels.. esp a version that works with 3rd and 4th gen TCM's. glad you stayed vigilant on the C4.. ive heard of many issues there with people home building and either havinbg to tight or too loose of clearance because there isnt a truly selective set for it.. although many trans shops have various thicknesses of steels and backing plates laying around just for that occasion.. somethign ther home builder doesnt have ..


I bought a real Nexiq and have had zero issues with it.. a buddy of mine bought a chinese knockoff and has had zero issues with it working on everything.. ive only heard of issues on some of the older ones where it was impossible to get firmware updates... not sure on updating the newer knockoffs but it seems like they work pretty good.



when I talked to allison about getting DOC it was a bit of a slippery slope.. I wanted to purchase the advanced edition with reprogramming and get a login account.. they were more than willing to sell it to me but because im not an allison dealer or employed by one they wouldnt give me access to reprogramming features online.. (no CIN access means PCCS is no good for much other than re-burning existing calibrations).. even if I took the necessary classes (and it looked like that was going to be tough not being a dealer.. if you go to sign up for a class they want your sponsored dealer info... so it was pretty much worthless to buy the advanced software..



I guess they are protecting their dealerships from 3rd party shops doing allison work





-Christopher

[Flipmode]

A couple of weeks ago i was showing a buddy the issues but it started and shifted into forward and reverse without a single light going on. The interesting thing is after initial start up the battery voltage stayed around the 12v level until I reved the motor, then it went up to around 14v. I haven’t paid much attention to that through these issues with the low voltage. Is that normal to have a delay on the alternator kicking in? I’ve started it a few times since then and it will drain the battery until the motor is reved. I’m really thinking that may be the source of the low voltage codes.

Drove it around the block and It stayed in 1st gear and wouldn’t shift. No check trans or engine lights. No Speedo function. Drove back to driveway, tried to reverse in and went into shift inhibit after a few feet. Put back into reverse and it moved a little then shift inhibit again. Put back into reverse a third time and was able to back all the way in without shift inhibit.

I decided to go the knock off usb link route. I found a seller on eBay that shipped from the US so I could get it in a few days. They emailed a link to download the software. Unfortunately, I couldn’t get the software to download correctly so the seller ended up shipping me the files on cds. I had to recruit a buddy who knew what he was doing to get Allison doc installed properly. There were several big issues with the supplied software files that had to be overcome. There is no way I would have been able to figure any of it out by myself. It is an old version I believe from 2008 which is still newer than my bus so not sure if this is related; I was only partially able to get it to connect. I tried several ways on configuring the ports and sequence plugging the controller in but was not able to get the full connection to see operations and codes. I was able to receive info on the Data Bus Viewer that showed it had some communication with the TCM. I’m posting a few screenshots of the program in ‘action’. Not sure if the reason I can’t get full communication is my software or if it is indeed an issue with the TCM. I’m really thinking the software as the Allison tech that came out a while ago was able to communicate fairly well. I think I’m going to have to find some newer software.

[Flipmode]

So a couple of variables that I’m thinking of currently: I saw a video that said in the bottom left corner is the program’s remaining time until it needs to be renewed by Allison, in 60 day cycles. My screen just has 00:00:00 in that spot which may mean it’s expired. When we were loading the software the keys and passwords didn’t match up to what the software supplier said they were (imagine that…lol). We were successfully able to maneuver around the 30 day trial password and keys as well as the reprogramming part, but called it good enough once we hit the TAC Data part and hit the same roadblock. My buddy had some ideas on the workaround, but I decided to try without it as we’d been at it for several hours by that point. So not sure if any of that is hindering the full performance of the software.

Now another thought is that the Allison tech was trying to update the TCM while he was out. He was successful in resetting the adaptives but I thought he said he was unsuccessful in updating it despite trying it twice. Might it have been successfully updated and now it’s not compatible with older programs?
More things to wade through….