Allison 2000 Range Inhibit

rbmcveigh · 09-16-2021, 11:59 AM

I have a 2005 Blue Bird with the Cummins engine and the Allison 2000 Transmission. The transmission cooler line blew off and the temperature got up to about 225 before it was noticed. Towed the bus back and got the line replaced and transmission refilled. Initially it drove fine, just a little sluggish. Then the Range Inhibit light came on.
The bus will go into reverse and drives great, no issues. But if I put it into any forward gear, even without the accelerator depressed, the range inhibit light kicks on in about 4 seconds. The bus will not move, so its not like its going into limp mode. If I shift between any of the forward gears, the light will clear, but comes back on in about 4 seconds.
So far, all the speed sensors have been replace and the pressure manifold module internal to the trans. Did a full transmission flush and refill, fluid level is perfect. I checked all the wires from the transmission to the TCM and haven't found any grounds or wire damage. I put in a different TCM from the same model and it still throws the range inhibit after about 4 seconds.
Any ideas on where I should go next? No, there isn't any check engine or transmission lights that come on and no, I don't have access to the Allison DOC software.

ewo1 · 09-16-2021, 12:42 PM

Quote:

Originally Posted by rbmcveigh

I have a 2005 Blue Bird with the Cummins engine and the Allison 2000 Transmission. The transmission cooler line blew off and the temperature got up to about 225 before it was noticed. Towed the bus back and got the line replaced and transmission refilled. Initially it drove fine, just a little sluggish. Then the Range Inhibit light came on.
The bus will go into reverse and drives great, no issues. But if I put it into any forward gear, even without the accelerator depressed, the range inhibit light kicks on in about 4 seconds. The bus will not move, so its not like its going into limp mode. If I shift between any of the forward gears, the light will clear, but comes back on in about 4 seconds.
So far, all the speed sensors have been replace and the pressure manifold module internal to the trans. Did a full transmission flush and refill, fluid level is perfect. I checked all the wires from the transmission to the TCM and haven't found any grounds or wire damage. I put in a different TCM from the same model and it still throws the range inhibit after about 4 seconds.
Any ideas on where I should go next? No, there isn't any check engine or transmission lights that come on and no, I don't have access to the Allison DOC software.

You're probably gonna need to find someone with the Allison DOC software and pull codes.
My best WILD guess is that you overheated the trans. scored the internals and maybe jammed up a valve body.

This is a wild guess but skip all the wild guessing, you need to pull codes!

Is there an Allison dealer near you? I would see what they charge to come out and pull the tranny codes.

Booyah45828 · 09-16-2021, 01:36 PM

100% pull the codes and look at live data.

That is where you should go next. Anything outside of that I'm afraid is a waste.

Shotgun blasting parts at it might seem like a quick, cheap, and easy solution, but rarely does it ever actually solve anything.

rbmcveigh · 09-16-2021, 03:33 PM

I agree that I should pull the codes, that would be great, but there isn't anyone nearby that can come out and pull them, so in the interim, I am finding the parts that I know are bad or failing and replacing them first.
I pulled the lower half of the trans apart and found what appears to be sand (non-metallic) on one of the solenoids (definitely granular in shape). All of the solenoids passed the energized and de-energized benchtop tests as well as the air tests.

o1marc · 09-16-2021, 03:34 PM

225* is certainly nothing to be concerned about, it's within normal operating range. The issue is probably not related to overheating the trans.

ewo1 · 09-16-2021, 03:45 PM

Quote:

Originally Posted by rbmcveigh

The transmission cooler line blew off and the temperature got up to about 225 before it was noticed. Towed the bus back and got the line replaced and transmission refilled.

Question:
What color was the fluid that was leaking when the line came off, green or red?

Question:
When it was towed in, did they pull an axle or disconnect the driveshaft?
And how many miles was it towed and at what speed?

I only ask these questions because if the trans was low on fluid and the transmission was not disconnected there is a possibility it could have overheated and cooked while towing.
I am not saying this is the trouble but if towing precautions were not observed this is something you got to keep in mind while trouble shooting.

I still say you need to pull codes first!

ewo1 · 09-16-2021, 03:51 PM

Quote:

Originally Posted by rbmcveigh

I pulled the lower half of the trans apart and found what appears to be sand (non-metallic) on one of the solenoids (definitely granular in shape). All of the solenoids passed the energized and de-energized benchtop tests as well as the air tests.

I have a complete manual for the tranny but it is 8mb. to large to upload here.
PM your email addy and I'll send it to you in the morning.

In the meantime I uploaded a internal parts diagram for the tranny.

Ok so I went ahead and broke down the service manual into 5 downloadable sections under 2 mb each. I hope you can find some usefull information or direction with these.

rbmcveigh · 09-16-2021, 04:10 PM

Thats what I was thinking initially, but maybe hot enough being an older bus to burn out a sensor or a wire.

rbmcveigh · 09-16-2021, 04:14 PM

ewo1:

The fluid that came out was a burnt red, apparently it had been awhile since the trans was fluid was replaced. It wasn't coolant, but the coolant was a little low. When I finished draining the trans fluid, there wasn't water in it.

As for towing, it was towed about 2 miles (probably shorter) at about 20 mph. The driveshaft was connected and the trans was in Neutral with the bus off. We did top off the fluid prior to towing though. When we got it back to the shop, it was just a little under the full mark, so we lost maybe a quart while in tow.

rbmcveigh · 09-16-2021, 04:18 PM

ewo1:

The manual that you uploaded in chunks I actually have already. Thats where I got all the wiring diagrams to shoot them and check their continuity. Everything electrical within the trans has checked out. I am going to finish cleaning and putting the lower half back together. If I can't find anything obvious when I am done, I may have to outsource and see if I can find someone with a scanner that can come out.
Btw, when I changed out the pressure manifold, I was able to get it to at least go into limp mode. Before, it would only go in reverse!

magnakansas · 09-16-2021, 06:30 PM

I have this mental image of the forward clutch pack slippin like crazy and the internal speed sensors are smart enough to know that all is not well. hence the light.

william

rbmcveigh · 09-16-2021, 07:46 PM

I am not sure, but if I disconnect the Grey plug at the TCM, I can get it into limp mode and it drives like it's in 3rd, no slipping. I think if the clutches were slipping that bad, I'd notice during limp mode.

cntryby · 09-17-2021, 06:00 AM

Quote:

Originally Posted by rbmcveigh

I agree that I should pull the codes, that would be great, but there isn't anyone nearby.

Where are you?

Booyah45828 · 09-17-2021, 09:00 AM

Quote:

Originally Posted by magnakansas

I have this mental image of the forward clutch pack slippin like crazy and the internal speed sensors are smart enough to know that all is not well. hence the light.

william

You and me both.

And towing it with the driveshaft connected and the engine off didn't help.

Something is off internally. It's not a speed sensor, it's not a solenoid, it's not anything electrically wrong. If it was electrical, you'd get limp mode when put into drive. You not getting that is telling.

This might sound dumb, but your fluid temp sensor relies upon being immersed in fluid for it to read correctly. If you blow a hose and run it out of fluid, the temp reading you see is very likely not accurate. So that 225 number might not be honest.

The codes will tell the truth. You're avoiding it, but reading them is a diagnostic step you can't skip. Honestly, the fact you don't get limp mode when shifted into drive tells me the trans needs overhauled/replaced.

ewo1 · 09-17-2021, 09:21 AM

Quote:

Originally Posted by rbmcveigh

I am not sure, but if I disconnect the Grey plug at the TCM, I can get it into limp mode and it drives like it's in 3rd, no slipping. I think if the clutches were slipping that bad, I'd notice during limp mode.

The gray connector is where the B+ power to the TCM is located along with the check trans light & range inhibit light. It is also where the 9 pin diagnostic plug goes to.
I can see why when you remove the gray plug you essentially bypass the tcm and the tranny defaults to 3rd gear-limp mode.

My friends bus recently went into limp mode, turned out the TCM got damaged. We suspect it was when we connected the battery charger it got a good spark (noise on the power line) and damaged the TCM.

I don't know what are the possibilities for you to swap out the TCM with another unit to see what happens...or maybe just wait untill you pull codes.

Also, a long shot here, but have you checked and tested the NSBU switch?

Booyah45828 · 09-17-2021, 09:27 AM

Quote:

Originally Posted by rbmcveigh

I am not sure, but if I disconnect the Grey plug at the TCM, I can get it into limp mode and it drives like it's in 3rd, no slipping. I think if the clutches were slipping that bad, I'd notice during limp mode.

Quote:

Originally Posted by Booyah45828

You and me both.

And towing it with the driveshaft connected and the engine off didn't help.

Something is off internally. It's not a speed sensor, it's not a solenoid, it's not anything electrically wrong. If it was electrical, you'd get limp mode when put into drive. You not getting that is telling.

This might sound dumb, but your fluid temp sensor relies upon being immersed in fluid for it to read correctly. If you blow a hose and run it out of fluid, the temp reading you see is very likely not accurate. So that 225 number might not be honest.

The codes will tell the truth. You're avoiding it, but reading them is a diagnostic step you can't skip. Honestly, the fact you don't get limp mode when shifted into drive tells me the trans needs overhauled/replaced.

Sorry, originally read that you could never get it into limp mode. Read the codes, that will give you your issue.

BamaBus · 09-17-2021, 10:51 AM

Quote:

Originally Posted by ewo1

I don't know what are the possibilities for you to swap out the TCM with another unit to see what happens...

Also, a long shot here, but have you checked and tested the NSBU switch?

See https://www.dieselplace.com/threads/...series.988005/

ewo1 · 09-17-2021, 10:59 AM

Quote:

Originally Posted by BamaBus

See https://www.dieselplace.com/threads/...series.988005/

Damn good find!

ewo1 · 09-17-2021, 11:03 AM

Quote:

Originally Posted by rbmcveigh

I have a 2005 Blue Bird with the Cummins engine and the Allison 2000 Transmission.

Hey dude, why is it that on this site you got a Cummins motor and on the other site you got a Cat C7 motor ?

Info found on another site:

https://www.schoolbusfleet.com/forum...TOPIC_ID=19462

Yes we have had a couple drivers report the range inhibit light coming on and the bus won't go into gear. We found that the drivers were operating the bus with the high idle/engine speed/cruise control in the on position. The powertrain control module will not allow the trans to go into gear if the engine idle is above curb idle speed or if the high idle engine speed control switch is on and the park brake is not on.

Another useful thread on this topic.
https://www.dieselplace.com/threads/...d-again.85679/

You may also like: