2013 GMC Sierra 2500 6.6 , lately when u drove the truck hard or pulling a trailer the dash lights and trans would randomly kick off for 3 seconds and come right back on WHENEVER YOU ACCELERATED, then randomly the right side would want to pull u off the road like the brakes were dragging on the right side . Then the stability control would flash . So I hooked my scan tool up and checked for codes . I had the u0101 communication lost with TCM. I unplugged the harness and checked for powers and grounds , everything is fine , I also continuity test also , then checked all fuses , their all fine . No the truck will not crank at all , my scanner can't connect to the ecm. Idid unhooked batterys and waited then re hooked them and notice the alternator cable is arching under the throttle body on a bracket . Any ideas ? I'm kinda ruling out it might be a TCM. But can a TCM make the ecm the not send let it crank ?
No crank no start after pin out TCM harness plug in
- Thread starter justfiremac2002
- Start date
If your arcing from the alt to the ground the TCM is most likely fried.
That's why I'm thinking also , had a 2011 Duramax do the same thing , replaced the TCM and range selector and sensor also. But could the TCM make it not want to crank ? I've seen threads saying they still start and run with a bad TCM , I thought if the prndl isn't indicating it won't
If your engine (ECM) does not think that the truck is in neutral or park, no crank is the result. It would be nice if you had a scan tool to tell you what the ECM indicates in this regard.
My scanner won't pull any codes up for ecm , won't let me connect
I’d highly suggest you fix the alternator wire before you do anything else to this truck. If that’s what’s causing things to fry, you’re gonna fry anything else that you put in this truck.
With engine off and key off, use a DVOM and set it to ohms, then put one lead in pin 14 and the other lead in pin six on the OBD two plug. You should see 60 ohms. If you see 120 you have a failed module on the GM canbus line. If you have 60 ohms run the test below this.
If you have 60 ohms, turn the key to run and put the ground lead to ground and the positive lead to pin 14 and see if you have anywhere between 2.3 and 2.7 V. Then do the same thing for pin six.
So fix that alternator wire and run those two test and let us know what you get
With engine off and key off, use a DVOM and set it to ohms, then put one lead in pin 14 and the other lead in pin six on the OBD two plug. You should see 60 ohms. If you see 120 you have a failed module on the GM canbus line. If you have 60 ohms run the test below this.
If you have 60 ohms, turn the key to run and put the ground lead to ground and the positive lead to pin 14 and see if you have anywhere between 2.3 and 2.7 V. Then do the same thing for pin six.
So fix that alternator wire and run those two test and let us know what you get
Will do thanks !
I have seen them not crank when there bad but i have also seen them crank when there bad. and i no they will crank when unplugged from TCM also. Yes i went to move a 2004.5 lly forgot about sending the TCM to AllComputers.com for repair until i put in gear to move and its like in all forward gears, i shut it down right then, hoping i didnt mess it computor up.