So my M1078a1 wont crank

[jmenende]

Howdy. My M1078a1 wont crank, bot even using the switches under the cab. The fuse panel has the k34 differential led on and my transmission controler is stuck in mode once I turn on the power switch. Im lost.

 

[Ronmar]

Well no trans-in-neutral, no starter… i would start by completely disconnecting power(12 and 24) and see if the trans controller will reset…

 

[jmenende]

I have the battery disconnect switch. I always leave it off but still the same after switching it back on. Im thinking a bad tcm.

 

[Ronmar]

That could be

 

[jmenende]

That could be

 

[fuzzytoaster]

I had this issue on a M1085A1 yesterday. Turn on the battery disconnect switch and start tracing voltage from the batteries through the physical disconnect and remote disconnect then up to the PDP. I'm 4 for 4 on bad remote disconnect boxes failing internally and allowing weird voltage through if any at all.

 

[Ronmar]

Yea, garbage in, garbage out…

actually I forgot to ask, can you access diagnostics(press both arrows at the same time)? Are there any codes stored. If it goes into giag mode, the display will flash D1, then 2 sets of numbers. Also note if the mode light is lit(Indicates a current fault). You press the mode button to step thru the 5 memory locTions(D1-D5), noting the 2 sets of numbers and mode light indication for each mempry location. Press both arrows or power down to exit diagnostic mode. If you press and hold both arrows for 10 seconds the controller should beep and clear all stored codes…