Allison 2000 - TC Wont lock up

[Imfrankyj]

Hello everyone,


We recently converted a 2004 CE 200 international. It has the T444E with the Allison 2000 transmission. the bus has 220k miles but everything seems to work well.



we have taken it on some 3 hour trips this summer to test things out before a big trip without any mechanical issues.


On our last trip the torque converter quit locking up. This made for a long trip home. It is supper slushy! I didn't realize how much i appreciated the quick lock up these do!


Anyways I have check to make sure the brake lights are working correctly and not staying on and keeping the TC from locking up. And that doesn't seem to be a problem. Today I drained the fluid and pulled the pan and opened up the valve body. I didn't find any blockage. I also check all of the solenoids and they all seemed to work. I was hoping if there was a blockage maybe it drained out when I split the plate out but I guess not. I just got back from a test drive and no change. It is still is super slushy and no lock up.


Any other thoughts (other than take it to a shop)?

[cadillackid]

are you getting a check trans or shift inhibt light?


if the J1939 communications from the engine to the trans TCM goes defunct then the transmission will not lock its converter as it uses converter slip to determin throttle position for shift quality and schedule..



your check trans light should blink on when you first start the bus too. so you know the bulb is good..



-Christopher

[cadillackid]

these transmissions dont unlock with a brake signal like GMC's old 700R4 did..

[Imfrankyj]

No check trans light at key on or when running and driving. I just double checked. When the TC quit locking I got 4 codes: 164, 32, 110, and 247. They all cleared and didn't come back but of course TC still doesn't lock up. Would the communications issue show up as a scan code?

[cadillackid]

The comms error won’t show on an engine scan, the navistar ECM doesn’t care.
Allison doc scan will show it.

If the trans TCM fails to power up at all your trans will operate in 3rd gear only.
The bus would take off very sluggish and have a very low top speed compared to usual.

The only way I know to get codes from the allison is with a computer running allison doc, I know even my navistar servicemaxx won’t show them.

[Imfrankyj]

It seems to shift fine through all the gears. Just no lock up.

Is there free or affordable scan software like navistar?

[cadillackid]

not that I know of.. well not officially.. there are unofficial channels to obtain the allison DOC software for free. and it will work with the Nexiq or Nexiq Clone USB devices just fine.

[cadillackid]

just for continuity its a good idea to make sure that the TRANS fuse isnt blown in the dashboard fuse panel. since you are getting all the gears im not suspecting a power loss to the TCM, however the lack of a check trans light when you first start the bus is concerning..



I would expect to see that light on for a couple seconds, similar to your check engine light when you first start

[Imfrankyj]

I just pulled the fuse and checked it. Fuse is good. I started it and still no light. I moved between reverse and drive and the shift into gear sounded/seemed harsher but I did not drive it.

I pulled the dash and checked the bulb and it's good.

Any other thoughts?

[Imfrankyj]

I ended up taking the bus into a shop. They ended up rebuilding the torque converter but no change. Is it possible the torque converter is locking but the transmission clutches are slipping? Is that crazy?

[cadillackid]

A shop rebuilt the converter but didn’t run a diagnostic? Did they connect DOC to it? Verify throttle input and look for transmission codes ( not engine) Erich the lockup valve is calling, test for proper pressures ..

[CHEESE_WAGON]

Have trans fluid analyzed for coolant contamination if this bus uses an engine-coolant-supplemented transmission cooler. Cross-contamination can happen and coolant in the trans is no bueno.