Yesterday I had to replace 2 tires due to a poor alignment. After having the tires replaced, I brought my 08 tahoe hybrid for an alignment. I actually had to fight with the staff to adjust the camber (they told me it was close enough to spec, even though I told them it caused the abnormal wear in the tires). In the end it still pulls to the left (i will be going back), but its the real damage they caused that concerns me. Between the easy part of the alignment, arguing with them, and helping them do the alignment, they left the key on with the lights, radio, etc, etc, etc. The next thing I noticed is the guy working under the hood while my truck was still on the (lowered to the ground) lift. I went running over (as did the customer service manager), but it was to late. I don't know what he did with the jumper pack, but he was taking it off and the truck was running. The service engine soon light was on (showed generic codes consistent with having had a battery die), the battery indicator light was on, and a message indicated "service battery charging system". The mechanic cleared the codes, started, and restarted the engine repeatedly. The battery light and the "service battery charging system" light are still on. With truck off the voltage reads 12.6 - 13.5 via OBD-II, and running it varies from 12.7 - 14.5 or so, also via OBD-II. There are no more codes, but 18 pending codes that will not clear. 17 are identical "non-existent" codes that appear to be related to the reports of multiple modules sending messages at once and the computer storing the first message it receives, which means nothing at all. The other pending code is related to a battery that has died.

Anyway.... it sounds like I have tripped the "dreaded" GM power management system (que the ominous music). does anyone have any experience with this? More specifically, does anyone know how to reset the light without going to GM? Can I do it by doing something to the truck? Can I do it with a Scan Gauge? Can I do it by sending a command to the computer via the OBD-II? Can I do it with the Tech-II (which I don't have in hand yet, so it is the least preferable answer).


Thanks everyone,

Jt

 

You should be able to clear codes with a scan tool. If the ignition was left on without it actually "running" ( able to move in EV or engine power ) the 12V will go low fast and the resulting "brown out" will upset many of the vehicle's computers.

In 5 key cycles without any code re-setting lights should go off. Vehicle off time between key cycles needs to be a couple minutes. It would be a very good idea to get the dealer to record the codes and any Freeze Frames associated with them.

Then there is the DIY reset. Pull the 12V negative battery cable while it is off and let the system set 5 min to give it a volitile memory reset.

 

Same thing just happened to me. Went in for an alignment, and the service charging system light came on. It all cleared, turns out it was a loose quick release battery terminal.

 

Those quick release battery terminals are pretty cool. I was kind of shocked to see how clean they were on a 9 year old nearly 200k unit. GM builds quality stuff.