M1088 transmission trouble

[Cgray]

Sorry it’s been about 4 yrs since I drove my 1088 and trying to refresh my memory.

Where are those three sensors and is there a way for me to test them? I have a diesel computer but have not been able to get codes on it figured out.

What you are saying makes sense under the conditions it is working and not working under. I believe you could be correct on the three sensors and want to either replace or test them.

 

[Ronmar]

One is in the front of the transmission case, down on the passenger side(input speed code 2214)), the Turbine sensor code 2215 is in the valve module inside the transmission and that whole module must be dropped to access that sensor. The output speed sensor(code 2216) is in the transfer case, you must drain the Tcase oil and it is under the cover plate on the rear middle/passenger side of center, (senses the middle gear in the Tcase). Its connector, shared with the 4x4 difflock signal is on the front of the transfer case…

since it is a turbine code and that one is the most difficult to access, I would start by going hand over hand on every inch of wiring and check every connector between the transmission Control Unit in the cab and the connection down into the valve module on the passenger side of the transmission…

you can do ohm tests on the sensors, that procedure and the specifications are in the MD3060(covers MD3070PT trans) troubleshooting manual.

Google TS2470EN and you can download it from many locations. Not sure if it is available here in the manuals section on SS, never looked for it…

Good Luck!

 

[Cgray]

Thanks for taking the time to write that out. Send me your Venmo and I’ll buy you a six pack .
I’ll run those wires down and check the trouble shooting guide. Thank you very much

 

[Delirium]

@Cgray Any update from your efforts here? I recently scooped up an A1 and am running into the same issue, particularly when getting going from a stop once the truck has started to warm up. I've started troubleshooting to eliminate the low-hanging fruit of trans fluid level, fluid state, filter state, and am going to start pinning some wires this weekend to check electronic components and easily accessible wires.

I'll also echo the possibility of a 'wet' keypad as previously suggested by NDT and Suprman, the truck has the original clearance lights and gaskets which I need to replace, and had allowed some pretty noteworthy water intrusion into the cabin during heavy rains.

 

[Cgray]

@Cgray Any update from your efforts here? I recently scooped up an A1 and am running into the same issue, particularly when getting going from a stop once the truck has started to warm up. I've started troubleshooting to eliminate the low-hanging fruit of trans fluid level, fluid state, filter state, and am going to start pinning some wires this weekend to check electronic components and easily accessible wires.

I'll also echo the possibility of a 'wet' keypad as previously suggested by NDT and Suprman, the truck has the original clearance lights and gaskets which I need to replace, and had allowed some pretty noteworthy water intrusion into the cabin during heavy rains.

I sent the transmission push pad to be rebuilt and replaced. It didn’t help but keypad looks nice.

Texas Instruments place was not really helpful as they cannot test the TCU. They say they hooked it up with no results. They said they cannot bench test the military TCU, so kind of waste of time.

I am not sure what to do next.

 

[Delirium]

10-4, at least you got a nice shiny pad out of it. I'll hit up more of the usual suspects over the next few days and build a list of the tests I've run and their respective results.

 

[Delirium]

@Cgray FYI, haven't yet confirmed a solution but I found a few problems with my transmission that are likely culprits of the behavior. I started a separate thread here.