Diagnosing Allison 2500 Transmission Issues on 2007 Thomas C2 Freightliner

[osg828]

I have a 2007 Thomas c-2 Freightliner I bought with Check Transmission light on.The bus did move with no problem when I got it,then it sat for a while and I had to floor it to get it to move,reverse was fine.Now it won't move either way.I read all the stuff about brakes being locked up,rusted,and so-forth.I jacked it up ,took back wheels off,put it in gear,and everything moved fine.Put it back together and still have same problem.Note this does have Allison Transmission in it,so debating to get a used tranny for it or am I missing something,I bought this for storage,but would like to move if I have to.Any help would be great,also having trouble finding diagnostic port,I bought a scanner that should work. Thanks
also already changed fluid and spin on filter,nothing was in the pan.

 

[nikitis]

If not going to move it much, buy a used trans if the same type keep your TCM, and just swap it.

Also make sure your trans has full amount of fluid. They don't move at all if it's underfilled.

 

[Mr P]

Diagnose BEFORE a trans swap. Figure out what trans you have and how to communicate with it.

 

[ewo1]

Diagnose BEFORE a trans swap. Figure out what trans you have and how to communicate with it.

yup!

Allison makes quite a few different trannies... but people keep just saying Allison...
It's like saying Chevy... which one?

OP says there was no trans fluid in the pan...
So much for pre-trip or pre purchase inspections!

 

[Mr P]

"nothing in the pan"....to me means (assumption) no debris, broken parts, ect.

 

[nikitis]

Nothing in the pan is why I stated try filling it up with trans fluid and see if it moves at all. (Assuming no debris it should)

 

[Mr P]

Written communication between strangers is interesting, to say the least.

 

[BamaBus]

...also having trouble finding diagnostic port,I bought a scanner that should work. Thanks
also already changed fluid and spin on filter,nothing was in the pan.

I have an '02 Freightliner with an Allison 2000 and the diagnostic port is under the dash behind the heater box just left of the exit door as you go out. Of course, this location may have been updated on the 07.

What scanner did you purchase?

 

[osg828]

"nothing in the pan"....to me means (assumption) no debris, broken parts, ect.

correct,no metal,or chunck's of anything,just Fluid ,and its a 2500 if that helps anyone..

 

[ewo1]

correct,no metal,or chunck's of anything,just Fluid ,and its a 2500 if that helps anyone..

This helps, now we know what chevy you got!

First things to check is power to your TCM. First check the TCM fuse, should be a 15 amp If I remember correctly. then you need to check the integrity of the trans wiring harness. On my MD3060, twice I had issues with the wiring and both times if was corroded pins in the harness, connector by the trans, that got water in it and eventually corroded.

You also need to verify that the terminating resistors on the data cable are still good. They do open up which causes the TCM to go crazy.

you also need to pull codes on the tranny...do you have Allison Doc?

you are miles away from pulling that trans out. you need to check all your electrical first.

 

[osg828]

This helps, now we know what chevy you got!

First things to check is power to your TCM. First check the TCM fuse, should be a 15 amp If I remember correctly. then you need to check the integrity of the trans wiring harness. On my MD3060, twice I had issues with the wiring and both times if was corroded pins in the harness, connector by the trans, that got water in it and eventually corroded.

You also need to verify that the terminating resistors on the data cable are still good. They do open up which causes the TCM to go crazy.

you also need to pull codes on the tranny...do you have Allison Doc?

you are miles away from pulling that trans out. you need to check all your electrical first.

I found Diag port,had quite a few codes which I probably caused,some cleared,these won't clear..FMI 7,FMI 6,SID 22,SPN 6918,FMI 5,SID 231,FMI 9...this one did clear,there were no Transmission codes.

 

[Bucket List Express]

yup!

Allison makes quite a few different trannies... but people keep just saying Allison...
It's like saying Chevy... which one?

OP says there was no trans fluid in the pan...
So much for pre-trip or pre purchase inspections!

I believe he was referring to there being no metal or clutch funk in the pan when he changed the fluid.

 

[ewo1]

I found Diag port,had quite a few codes which I probably caused,some cleared,these won't clear..FMI 7,FMI 6,SID 22,SPN 6918,FMI 5,SID 231,FMI 9...this one did clear,there were no Transmission codes.

Cummins engine ????
these are engine DTC codes.
I asked if you have Allison doc. You will need Allison doc to pull tranny-communication-codes.

Did you check the fuse for the TCM and is power getting to the fuse?

SId 231- FMI 9 = J1939 data loss of data signal


Freightliner Service Bulletin 54-320

New BHM Software for Switch expansion Module Fault SPN 6918 FMI7

On some New Business Class M2 and 108SD/114SD vehicles, bulkhead module (BHM) fault code SPN6918 FMI7 displays at key ON, despite all switches showing that the correct parameters are loaded and a represent in Diagnostic Link®.

This issue is resolved by upgrading BHM software 7.41 to BHM Software 7.43. Use the instructions in this bulletin to update the BHM software level.

Master Code List
Conventional FS65
Saf-T-Liner C2
Saf-T-Liner HDX, HD, ER
Saf-T-Liner EF, EFX
All years

 

[osg828]

I do not have allison doc,nore do I know what it is,the code reader I have does list the transmission,when I scanned it,it said no codes found and no history codes.I did not have a chance to check fuses yet,gotta find fuse block,and I live in south jersey and were having one of the worst winters we have had in 30 years.

 

[osg828]

I do not have allison doc,nore do I know what it is,the code reader I have does list the transmission,when I scanned it,it said no codes found and no history codes.I did not have a chance to check fuses yet,gotta find fuse block,and I live in south jersey and were having one of the worst winters we have had in 30 years.

 

[ewo1]

I do not have allison doc,nore do I know what it is,the code reader I have does list the transmission,when I scanned it,it said no codes found and no history codes.I did not have a chance to check fuses yet,gotta find fuse block,and I live in south jersey and were having one of the worst winters we have had in 30 years.

I grew up in Union county...Don't miss it one bit after 30 years of Florida sun!

If your TCM fuse is blown or missing then NO code reader can read it. It is that simple. The TCM needs power to communicate.

also, you said the "check Transmission" light was on.
If the light says on then yes, you should have a code, in most all scenarios.
If the data link has a comm failure, trans lght might also light up but if your code reader is talking to the engine TCM, then I would not suspect, yet, the data link to be bad.

Whenever troubleshooting electronic engines, clean and solid power is always step #1.
these electronic transmissions, when the check trans light comes ON, they will go into limp mode.

If your wiring is in question or if you do not have clean solid power/ground then the TCM will not respond correctly.

The fuse for the TCM is NOT gonna be found in the fuse panel/block. It is typically on it's own wire, usually directly to the TCM itself...usually.

I do not know where Freightliner puts the TCM fuse but on most Internationals you will find it in the battery box.

 

[ewo1]

1000 AND 2000 PRODUCT FAMILIES TROUBLESHOOTING MANUAL—ALLISON 4th GENERATION CONTROLS​

Limp Home Test
With the ignition in the OFF position (engine not running), the selector in N (Neutral), and the parking
brake set, remove the 80-way connector at the TCM.

It will be necessary to provide battery power at pin 41 of the 80-way connector in order to energize the
neutral start relay. This can be accomplished by using a jumper wire between pin 10 and 41 at the 80-way
connector.

When the engine is restarted, the transmission will default to a “limp home” capability. In this state,
PCS1 (de-energized) allows C3 clutch to be applied. If the selector valve is moved to the reverse range
position, main pressure will be routed to C5 clutch, allowing reverse operation. If the selector valve is
moved to the drive range position, main pressure will be routed to C1 clutch, allowing third range
operation.

This allows a technician to use “limp home” capability to determine if a hydraulic or an
electrical problem exists. If reverse and third ranges are available in “limp home,” an electrical failure
may be indicated. If only one of the two ranges or neither was obtainable, this may indicate an internal
hydraulic failure (failed clutch, stuck valve, or solenoid failure). The clutches that could possibly have an
indicated failure in “limp home” are C1, C3, and C5.

 

[osg828]

Glad your in sunny Florida,right now we are just on the line,cold rain/snow.Thanks for all the info you are giving me,I am learning,like I said I have always worked on cars and still do to some extent.Seems these days not many good mechanics out there,anyway I am learning as I go on this Bus.Yes the trans light is on,and when I bring the Transmission section up on my scanner it list pressure and so-forth..too many things to remember,pressure stays at 0 % no matter what,so what your saying about data link makes sense.I will get on the hunt for that fuse..Again thank you greatly for the info.When I first got the Bus I did buy a repair manual on cd,which has lots of information but not very well laid out.

 

[Mr P]

I'm not a bus guy. I'm a car mechanic. In that world, when a "computer" (ECM, TCM, BCM, ect) has a "bad fuse", it's not gonna communicate at all.

Pressure is 0%....is that a command or actual?

 

[osg828]

I'm not a bus guy. I'm a car mechanic. In that world, when a "computer" (ECM, TCM, BCM, ect) has a "bad fuse", it's not gonna communicate at all.

Pressure is 0%....is that a command or actual?

Not sure about that,still learning this scann tool,not the same as all my other ones.