Weird problem with 05 uplander 3.5L Going uphill towing a trailer. Van died, now no start and the red PRND123 (gear shifter light) doesn't come on. All the fused are good everywhere. Haven't check relays. Something tells me maybe TCM, since the PRND123 light are out but i don't know. When i crank, the speedometer and tach needles just jerk in convulsion. Battery good. Anyone had something similar happen? Thanks!

 

try running a full diagnostic scan on it with a pro tool

 

There's no communication on the serial class 2 buss. Scanner doesn't connect. I got the communication comb disconnected, will check for individual modules, maybe something's jamming it. I think probably either ABS or TCM modules. Very strange problem. Thanks for the input.

 

 

This was a very very simple fix. One of the smaller ground wires that grounds to the transmission broke off, the computer lost it's grounding and the whole thing shut down. I crimped up new connector, replaced the other ones for good measure, cleaned up all the mating areas and it started right up no problems! Hope this helps someone, check your grounds to the transmission bolts first!

 

Thanks for the report. Glad you got it running.