Good morning foreforum, I need help with Allison codes and your best recommendations to get the retarded active again. I am wondering if my big trans plug needs to be disconnected and contactor paste applied for proper signal input, recently had KC-2060 repaired and still getting a low-voltage for tps, even though the king cruise is working properly after a connector was repaired.
These issues arose after staying near the florida Atlantic coast last year for several days with heavy salt air in August weather. The drive home I lost throttle input for a few seconds, and retarder activated, after that issue throttle came back online a few seconds later but retarder was not functioning properly after that. Later on I had issues getting trans pad to let me shift into gear without first revving engine a little then when back to idle it shifted into gear for me, this only happened 2x after the throttle input was lost. After that trans selection worked perfectly every time afterwards but Allison retarder was still inactive. Cruise works fine
I have the following trans codes appearing on touchpad that won't clear
1998 U295 8.3 P-Pump (mechanical engine)
Allison MH3060 codes
3323-sump oil temp sensor failed high
2112-tps low voltage
6223-retarder oil temperature sensor failed high
6423-retarder modulation request, failed high
Thats a number of codes, might want to start with something simple like pulling the connectors from the Allison ECU and using some contract cleaner on them, maybe some corrosion occurred due to the salt intake.
Verify good 12+ VDC to the Allison ECU.
Verify good for the Allison ECU GROUND as well.
Thank you, that's what I was thinking too, I'll use some compressed air to clear dust and debris before pulling the connector.
All of the exposed Allison connectors seal up pretty well... amazingly actually - I'd avoid opening any you haven't.
98 3060 - that's a wtec2 correct?
Does a 98 have a VIM? (Might be buried down below the shift pad?)
Verify chassis voltage.
Think I'd start under the shift pad and retarder control/switches....contact cleaner and dielectric grease on all those plugs...then check if there's a connector in the gen fan compartment below there ..
I'm not well versed on the king control and it's interface to the Allison - since you've worked on that I'd move to any connections there next.
I don't know what wtec2 is
Here's a good place for info and repair of the Allison stuff IF that happens to be what you need.
Transmission Instruments (https://www.transmissioninstruments.com/)
WTEC is the "computer" for your transmission - referred to as ECU or TCU. (Technically I think the wtec3 is considered an ECU and the wtec2 is a TCU but I am not a transmission guru!) the wtec3 came out in 98 so you probably have a wtec2. Your TCU will most likey have two plugs on it.
If you Google Alison WTEC2 you can download a troubleshooting manual.
You can check a lot of things with a multimeter on pairs at the TCU plugs.
Assuming you're pulling the codes off the shift pad?
Have you cleared the codes?
Id clear codes the disconnect all power sources to the coach, then grounded your battery power cables to clear all residual voltage. Check the resistance between the ground pin at the TCU and your chassis battery lug.
Troubleshooting this transmission with a tester is difficult but can help you rule out a lot of things.
I want to provide an update on this topic incase anyone else needs help with this issue. I took the coach onto a third party Allison repair shop in Orlando, FL, they diagnosed a chaffed wire causing all the codes, they ran a new wire from trans selector/controller to the transmission itself. That one wire was causing all my code issues.