I have a strange problem where power is cut entirely to my Tahoe. Approximately every 3 days or so, when I go out to my truck it will have no power. Sometimes the dome light comes on, sometimes it does not. When I turn the key, nothing. I if I open the door, then close it again, I hear the chime and everything comes back on and I can start it up without issue. The only aftermarket equipment is a headunit (along with interface modules for gmlan and onstar) and headrest monitors (switched power). The battery is not draining completely, as it starts without issue once power is restored. The battery was replaced last summer.

Any ideas?

 

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I'm sorry to hear about your frustration with your Tahoe. After reading the description of your problem, it sounds as though there may be a short somewhere. I state this as a suggestion, not a diagnosis.

I encourage you take the vehicle in for an inspection. After a physical inspection, a certified technician will be able to offer a more accurate diagnosis.

Please keep us posted.

Louis
GM Customer Service

 

The "interface modules for gmlan and onstar" is the prime suspect. A misbehaving module on the GMLAN network can bring down the whole network, e.g., preventing the door switch from communicating to the BCM that the door is ajar or the BCM from communicating to the ECM that the key is in start.

 

Yeah, that's my first and most logical culprit (considering the module has other known issues). Trying now to locate an inexpensive factory cd/mp3 unit to toss back in it (could kick myself for giving the factory away!).

 

Well, so much for that idea. Factory radio in and a few days later it happened again, so my aftermarket equipment is back in now. It's just an annoyance, but still something I'd like to track down. Seems that 2 door open/close sequences is enough to reset things - for instance, I'm usually alone and can open my driver's door and close again to reset. This time my son hopped in the passenger door and closed it before I got to the garage. I got in the driver's side and didn't even notice that it had happened again. The only evidence I had was the radio was reset to factory and my TPS sensors weren't communicating (takes a few minutes).

 

If it really bothers you, take it in for a full scan. There may be a module somewhere with a stored code that can shed a light.

 

+1, my concern is that the tech may start shotgunning expensive components because it could be a difficult issue to resolve...maybe a re-seating of the BCM connections might be worth a try....

IF you chose to do this be sure to disconnect the battery prior to removing any connections....

 

I'm starting to wonder if it's battery-related. I remembered that a few days before this started, the Tahoe was barely able to start (low battery) after sitting for 3 or 4 days. The more I read, the more I see that this year (and possible others) have a known drain issue. Is there any way to verify if the updated BCM program has been applied?

 

The dealer can check it.

 

Before making plans to take it in, I did a physical inspection tonight. I found that the battery I had replaced last summer isn't tight on the positive post. That awful little clamp won't tighten enough to get a firm grip, either. Does the OEM battery have abnormally large posts? This thing is cranked all the way down and I was able to lift the whole cable off with my hands.