Allison 6sp: TCM trouble and much more

slayer2500

New member
Jul 30, 2013
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my 06' Dmax just crapped itself..he needs some real help. the motor will try and crank a little when i turn the key in the FIRST position, but nothing when you actually turn it all the way. the ABS light is on and the parkbrake light, the information center reads that the brake system needs serviced and also the 4WD needs serviced. got it to start while the key still has that problem. putting it in gear was rough.. jerks when you put it in reverse and drive, then it wouldn't shift above 1st gear or go above like 1500 RPM

the only DTC's its throwing is Lost communication with transmission control module. i checked the fuses for voltage on both sides, all good.

WHY IS THIS ALL HAPPENING AT ONCE?!?! and could one thing just lead to another?? what is the root problem? could it all just be from the ABS? or viceversa? please help.. just a normal day.. haven't been rough on it or anything
:confused:
 

chevyburnout1

Fixing it till it breaks
Aug 25, 2008
2,368
1
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Berthoud, CO
The whole cranking over while in the acc position makes me think ignition switch is weirding out, which could cause all of your issues.
 

slayer2500

New member
Jul 30, 2013
2
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sorry i checked it again and it actually cranks for a second in the ignition position, but before you turn the key all the way. not the ACC

it is now throwing a few more DTC's, P0621 Generator L-Terminal Circuit
U1301 Class 2 Data Link High