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Transmission key pad blinks “Do Not Shift”
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As Tom noted above you should be able to get the transmission codes from the ECU by turning on the igntion key , no need to start vehicle. Then flip up the toggle switch that shoudl say ATEC. It should be located near the DDEC diagnostic connector on the ceiling of the service compartment under the driver. If it is working then the “check Trans” light onthe dash will flash the two digit codes. Once we have that we can see what to check.
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thanks for the help. I don’t see any codes after turning on ignition switch and then selecting the ATEC switch on. Nothing flashes. If I do the same with the DDEC switch I see the two codes listed previous.
I appreciate everyone’s advise and help. I have accomplished all the troubleshooting suggested with no results. Except for depowering the complete coach. That may need to wait till tomorrow morning. It’s been raining off and on.
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Here are the flash codes for the ATEC transmissions:
1984 96" with 8V92TA
(remodeled Liberty Coach)
Greenwood, MO -
You may have a burnt out bulb for the check transmission light Monty. Does it light up when the key is turned on for the self check? Just another thought.
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It tests during power up….. I wish the fix was that easy!
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Bus has been towed to closest Allison repair facility in Kingsport, Tn. (Clark Power Services). Thanks for advice and after removing axles used cardboard for axle covers. This helped with the lossy of oil!
The Chassis wiring has been checked and is good. No codes in ATEC system!
We are suspecting the keypad or ECU. Currently Clark Power Supply is trying to locate a used keypad for testing from their other shops. Any ideas where to find a keypad ( pn-23048155 28/93)? I may need a rebuilt or used unit.Looks like the bus will be in TN for a while.
Jon/Tom. Feel free to move this posting to the appropriate topic.
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Good feedback Monty. Let us know the final outcome.
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What was the final fix?
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Returned home yesterday!
The ATEC ECU was the problem. Replaced ECU p/n 1228283 with a reconditioned unit supplied from Jultech Incorporated, located in MN.
Clark Power Services in Kingsport, TN did a great job troubleshooting the complete system from wiring to sensors and shift keypad. They were able to locate a test ECU to verify the problem. I highly recommend them for Allison work!
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Glad you Made it home safe.. thanks for the update on the final fix !
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With a properly functioning ECU, should you get a code that basically means “No codes”, akin to 25 on the DDEC? Monty didn’t have any codes flash at all when in diagnostic mode, which could perhaps be a clue for a bad ECU in the future.
Would that be what code 69 referrs to above?
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I had a similar issue with my transmission. Error code was that there was an issue with the speed sensor. Both the engine ECU and transmission modules have been replaced. Once it was towed in and they said it had been fixed. Issue happened again. Was throwing code 22.
What I found on my particular year of bus was that the relays that sit above the transmission module have an issue. One seems to get hot. I just need to swap the hot relay with a cool relay and things are good for a long while. (note that they don’t make that relay anymore. Prevost found one that seems to be working except for getting hot) It has been suggested that there may be a ground wire issue. I’ll be troubleshooting that next as all the shops that this has been in have not been able to find the issue.
Note that I replaced the speed sensor and that item had not been touched in years. Was a pain to get removed. I find that many times I need to sit down and figure this out. Would have saved me a tow and flight back to get the bus.
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Rod,
Could you post a photo of which relay is getting hot? Thanks, John
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Rod,
Ouch , A tow and a flight. When You could have got it fixed by switching a relay. That gives Me that “BAD ” feeling in the pit of My stomach. Something so simple can cause a lot of grief. And they do not make them anymore. I hope You find a source for some spare relays to keep on hand.
I am happy that You figured it out and shared Your experience. Threads like this is why I read everyday. Your info could help another member from having to be towed to an unknown shop in a strange place.
Safe Travels…
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