bpolak

I was in the process of going to the market, my Tahoe was running fine and showing no signs of struggels. I cam out and attempted to start and my truck decided that it was not going to start. It had service engine lights on, telling me to service the 4wd trailer brake, traction control and power steering, Then told me that the engine power had been reduced. Upon checking it looks like i lost connection with ECM, TCM, Can Bus Communication, TCM Requested MIL Illumination. Codes are as follows, U0101,U0100 (Stored), U0073 (Permanent), U0101 (Permanent),U0101 (Pending). I am unsure what to do, truck is sitting at the shop until at least tomorrow but nothing was wrong with it, it was running fine. Has anyone else had this issue before and what did they do to fic?

mountainmanjoe

before you panic, modules can't communicate if they don't have enough power.
Did you leave anything plugged in or turned on?
1st step: get the charging system load tested. battery+alternator

tech2

If the codes go stored; everything will work normally until the fault occurs again. diagnose any pending or active codes. for u codes you need to know what modules set the codes and what modules have lost communication with the bus. This isn't easy and is best left to someone trained in bus diagnostics.

tech2

what mmj said is correct. bad system voltage can cause the bus to go down. Usually, low voltage dtc will set. if the battery was dead...do what mmj suggested.

bpolak

I am going to do that tomorrow morning before I go to work

bpolak

I think its worth noting that when I was sitting in the truck the dash was doing what it wanted. The car was attempted to start without me pushing the start ignition switch. It weas going haywire kept telling me to put it in neutral and would not recognize the directons (North South East West). It kept telling me to put it in park even when i was in park. It did not want to turn on until it got to the shop roughly 45-hour after the situation had started

bpolak

Updating again, brought it to the shop, they did not have until the 20th. Driving it to a shop about a half hour from me who will be able to look and diagnose situation same day. Possible wiring issue (bad ground) Will follow up again tomorrow with an update.