Lmtv m1078 wtec2 issue

[joestanley]

Was working on some light wiring, while having the dash pulled forward I heard a pop from the drivers side behind the dash, after this the Allison key pad turns on and off and the transmission control module just clicks from under the passenger kick panel, the truck still starts and runs but no longer has the transmission, was wondering if anyone has had a similar issue. I have spent some time looking at the issue but the schematic I got from Midwest military and the Allison wtec2 schematics are not exact to my truck so there’s confusion for myself, so before I send the modules out I was curious if anyone experienced something similar and had any advice, thanks in advance

 

[Ronmar]

On a wtec2 the tcu is in the drivers dash with the control pad. You should get clicks under the passenger dash as the Vehicle Interface Module is located there and it is filled with relays like Neutral start, reverse warning center diff-lock ect.

if you have a transmission display, have you tried to read codes stored in the trans controller?
with the display powered on, press both arrows at the same time to enter diagnostic mode. The display should show D1 followed by 2 sets of numbers, write those down and note wether the mode light is lit(indicates an active fault). Press mode to step thru the 5 memory locations D1-D5 and record any numbers stored there. - - instead of numbers indicates no stored codes.

Moving the dash and hearing a pop sounds a lot like a bare wire shorting to a sharp edge/ground in the dash.

there are 4 fuses associated with the transmission CB79(24V IGN) and CB35(12Vbattery) the wtec2 gets fed both voltages, cb35 is the 12v vampire load on the A0 LMTV. These 2 fuses in turn feed two more fuses located inside the VIM under the passenger dash, so check those also…