Allison key pad issue

[wgr4]

Today I was driving my truck and all of the sudden I felt a downshift and my transmission key pad went out. No reading at all. I got back to the house and the truck would not go in to neutral or reverse. i shut off the truck and then restarted and the key pad was back to normal. I backed the truck up to park it and the pad went out again. I shut it off and restarted and the pad came back to life but after a few minutes went blank. Has anyone else experienced this issue and if so, please shed some light on how to fix it.

Many Thanks,

 

[NDT]

Key pad dark could mean power interruptions to the Allison, or issues with the Allison keypad or transmission controller. The Allison does not have a "limp mode" like the 4L80E, if power is lost, it will not drive I believe. If you were still able to drive and auto shift with the controller dark, I would suspect issues such as water intrusion into the keypad. '97 and before is WTEC2, '98 and after is WTEC 3 controller. I would step through the Technical Manual section on "WTEC does not illuminate" and see what you can figure out. If you determine the controller or keypad is suspect, "transmissioninstruments.com" offers free diagnostics.

 

[wgr4]

Thanks for the info. I got in the truck this afternoon and started it up and drove it with no problems. I am going to keep an eye on this. when the key pad went out initially the transmission down shifted and I was able to drive home in a single gear. I think it stayed in 4th, however; I could not shift in to neutral or reverse without shutting off and turning the engine back on.

 

[Suprman]

If it's wtec2 ground the computer and replace your 24v dash power relay they are a common failure.

 

[TNriverjet]

Yeah, it sounds like a grounding gremlin.

 

[scottmandu]

Your allison keypad could also be bad I've seen a number of them do very weird things that ceased when the pad was replaced.

 

[Suprman]

Water gets in around the lights over the windshield and drips onto the keypad. Over years it works its way in and causes problems. I had one truck would put itself into drive.

 

[oregonfirefighter]

Water gets in around the lights over the windshield and drips onto the keypad. Over years it works its way in and causes problems. I had one truck would put itself into drive.

Now if would only run the Honey Do errands too

 

[wgr4]

Where on the dash is the 24v dash relay located?

 

[wgr4]

Sorry for being so vague, is it K25,K26, K34 or K37 in fuse panel?

 

[tennmogger]

My transmission shut down like that once. I found one of the two big plugs on the back/bottom of the key pad was loose. Last soldier to work on it did not tighten the retaining screws.

I had to pull the dash to get to it. The whole assembly was missing mounting screws too.