Hi everyone. I have an 08 Chevy tahoe hybrid. The 12v battery recently took a crap so I went and grabbed a brand new one. After I put it in the truck will not start. The security light is on on the dash but not blinking. I've tried the 10 minute and 30 minute tests. Checked all the fuses. Disconnected the black battery terminal numerous times and let it sit for 10/20/30 minutes. The radio/power windows/door locks/key fobs also do not work. I put a battery charger on the 12v battery hoping maybe it would charge the 300v HV battery in the back. If maybe it died with the 12v battery? Im not sure what the problem is. I don't have any PCM/BCM trouble codes. One thing I noticed is the line to show me what gear I'm in on the dash is also missing. Truck ran perfectly fine when parked. I'm stumped. I currently don't have the money to send it to the dealer.

Anyone help?

 

 

and to add to it... i have no communication with the theft deterrent module or the IPC

 

have you checked the fuses under the hood?
i suspect you lost a ground wire if multiple items are dead

there is two sets of ground wires under the driver side door were the chassis (frame rails). also check the ground wire under the hood that connects from the engine to the chassis (firewall)

also check the ground wire that connects to the it's the long thin one that snakes to the radiator area from the neg battery cable

I would check this first
this is the location of the BCM CHECK each wire for chafing or damage (might have had a hot 12v+ wire ground out as it sounds like) as you said the battery was dead DON"T replace any fuses if they're bad you have to fix the issue first

don't disconnect or unscrew anything you can open the fuse box cover though


do DISCONNECT THE battery first before messing with stuff..

https://newrockiesinc.zendesk.com/hc...0the%20bottom.

 

That missing line (under-score) on PRNDM means no communications between transmission and instrument cluster. Or TCM not awake.

The loss of many other functions could be an ignition or Body Controller issue

 

also i should mention check the relays a bad relay can prevent it from starting

 

When the 12V battery went dead did you try to boost your GM Hybrid to start it with the battery cables still hooked up?

 

Anyone has this happen. Mine will run perfect all day in and out shopping or whatever, then all of the sudden you get in and it won't start. Everything thing works but it won't start will say service hybrid system on dash. You wait an hour and it will start right up like nothing happened.

If anyone has any insight please share its a weird problem.. thanks

 

Gilly man yeah I reread your post and see this Quote "I put a battery charger on the 12v battery hoping maybe it would charge the 300v HV battery in the back" (THAT MEANS THAT YOU LEFT THE CABLES ON AND PROBABLY HAD THE KEY SWITCH ON AT SOME POINT WHILE CHARGING)
Safest thing to do if the 12V dies is to unhook the cables and charge the battery separately. Yes it is too late now for you but maybe others will heed that advice and save themselves some trouble and expense.

Now you have to have yours towed to a dealership (or a shop that utilizes a Tech2 and pass thru device) to reset the crash detection system.

https://f01.justanswer.com/TonyU82/00836f17-971a-41cf-83ab-3b1f753253f2_Hyrbid_Reset.png

 

loose wires somewhere metal expands loses contact or high impedance

cools down makes connection again..

i would check the harness under rear seats loose wire or chaffed/ shorted

DON"T touch the high voltage cables ORANGE

the battery pack harness is muti-color bundled.. maybe someone tampered with it or has came loose ..??