Electrical issue

[White Duramax]

Having an issue with my 2011 LML today. Coasted up to a stop sign and the abs and brake lights came on on the dash, when I got stopped the engine started surging up and down and then died. I turned the key off and restarted, it idles fine in park and does not surge, as soon as I put it in drive, reverse, or neutral it will surge up and down and then die. I disconnected the abs module-no change. I checked all battery connections-ok, the batteries are less than 6 months old, voltage is just over 14 at idle. I pulled the fuse panel up to check for any corrosion on the connectors, its clean. I haven't checked for faults yet but will in the morning. Just wondering if anyone has ran into this issue? Thanks

 

[Chevy1925]

Check codes but most likely tcm

 

[White Duramax]

I put a good tcm out of a 2012 in it, no change. Several modules have a U0121 No can bus communication with ABS/TC/ESP/CC. I was checking data and noticed the tbcm and transfer case module were showing 11.7 volts and the ecm and tcm were showing 12.2 with koeo. When running and acting up the tbcm and transfer case module voltages would drop down below 9 volts. I think my issue is voltage dropping to the modules that are inside the cab. Anyone had this issue? Thanks

 

[Bdsankey]

If you're dropping voltage I'd recommend to verify with a multimeter then check all connections.

 

[Chevy1925]

like Brad said, check your voltage at the batt, alternator and go from there. if the battery is dieing from not getting a charge, electronics will start dieing out and doing strange stuff.

 

[Mike L.]

Check ignition switch.

 

[White Duramax]

Figured it out. Passenger side battery was at 11.8 running and driver side at 14.4 volts. Narrowed it down to being the ground cable from the battery to the block, cable looked fine but once I had it out found corrosion in the end under the rubber at the block eyelet end. Had a new 1/0 cable made and installed, everything is working normal now. Thanks