Allison Wiring Problems

[dmaxalliTech]

Hey all, I just want to let everybody know what seems to be an increasingly common problem.

Bare with me as I have no pics.

Mike Tomac and Dave K. both had this problem on their trucks and hopefully I can help prevent future problems for ya'll

1. Find your TCM, its mounted on the fan shroud on the drivers side. It attatches to the shroud with two 10mm bolts.

2. Follow the wiring down from the TCM to where it goes along side the PCM cover.

3. Carefully inspect the wiring harness where the P/S line return hose is, the clamp is a spring style and has sharp little ears on it that like to eat into wiring harnesses. Pull the plastic conduit back and carefully inspect all wiring that runs throught it. The problem is that the wiring is rubbing on the clamp.

4. Reposition the return line clamp, at the pump, to put the ears facing down, repair any wiring that was damaged, if any. Tape up and reinstall conduit, reroute slightly and secure to avoid it rubbing again.

This chaffing could cause a multitude of problems because of the number of wires that run in this harness. Could save a trip to the dealer if you find this and fix it yourself.....

Email me if any q's

[TEXASTOUGHDMAX]

dmaxallitech--

Thanks for the tip. Went and checked it out. On mine there appears to be plenty of clearance around the clamp. Checked all the wires in the area anyway. Everything appears OK. I guess its to the dealer tomorrow.

Thanks for your suggestion.

[77TransAm]

Shouldn't you have called this topic GM wiring problems? smile.gif
Allison doesn't make vehicle wiring harnesses any more...

I thought a bulletin had been issued on this problem, because I remember having to check all of our trucks for the condition some time ago. I just went through all the bulletins for 2001, though, and couldn't find anything. If I remember right the problem was only with trucks built at one plant - I don't remember which one, though.

[dmaxalliTech]

Originally posted by 77TransAm:
Shouldn't you have called this topic GM wiring problems? smile.gif
Allison doesn't make vehicle wiring harnesses any more...

I thought a bulletin had been issued on this problem, because I remember having to check all of our trucks for the condition some time ago. I just went through all the bulletins for 2001, though, and couldn't find anything. If I remember right the problem was only with trucks built at one plant - I don't remember which one, though. Wiring harness is Allison equipped trucks only, wont apply to hand shakers and there is no tsb, but I did find a PI on it. I dont recall the number though.

[mdrag]

dmaxalliTech,

Thanks for the tip - it's been a while since the WIRE CHAFFING (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=3;t=002949) was discussed.

[dmaxalliTech]

I guess I didnt relize its been discussed already. That thread was before my DP days :D

I guess its a good refresher for all of us. I like the forum, I learn of all sorts of things way before I ever see the problem in front of me.. Keeps me on my toes.

77T/A,, You seem very knowledgable in the Allison dept. Do you work for them/with them at all? You have lots of good info. Thanks ;)