Unhooked Battery, now it won't start- Please help! *SOLVED*

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

DougAMiller

Full Access Member
Joined
Mar 10, 2016
Posts
489
Reaction score
791
Location
Colorado
No worries. I also thought it helpful to relate my uncle's experience as an example of why we recommend doing something a certain way in order to be safe.
 

wsteele

Full Access Member
Joined
Dec 26, 2020
Posts
1,731
Reaction score
2,351
No worries. I also thought it helpful to relate my uncle's experience as an example of why we recommend doing something a certain way in order to be safe.
Understand, if you are old enough and you started goofing around with cars early enough, most have witnessed the power in that stored battery and how anything metal that bridges the + terminal with just about anything else metal in the engine compartment turns to sparks and molten metal. :)
 

hagar

Full Access Member
Joined
Nov 13, 2010
Posts
196
Reaction score
146
Any chance you unhooked the battery while the key was in the on position?
 
OP
OP
S

Scrapman

TYF Newbie
Joined
Aug 21, 2021
Posts
28
Reaction score
15
Nope. The key was definitely in my pocket.

I will update as soon as my mechanic figures out the problem. He is short handed and having trouble hiring people just like everyone else.
 
OP
OP
S

Scrapman

TYF Newbie
Joined
Aug 21, 2021
Posts
28
Reaction score
15
UPDATE: My BCM (Body Control Module) was toast. Everything is back working with a new BCM and reprogram.

I guess the moral of the story is always unhook the battery before unplugging any electrical part; and Never unhook the battery with a component unplugged. (who knew the rear latch assy completes a BCM ground?!?)
 
Last edited:

donjetman

Full Access Member
Joined
Oct 22, 2018
Posts
1,558
Reaction score
2,767
UPDATE: My BCM (Body Control Module) was toast. Everything is back working with a new BCM and reprogram.

I guess the moral of the story is always unhook the battery before unplugging any electrical part; and Never unhook the battery with a component unplugged. (who knew the rear latch assy completes a BCM ground?!?)
07 Denali:I replaced the rear latch assembly without disconnecting the battery and didn't hurt anything?
 

hagar

Full Access Member
Joined
Nov 13, 2010
Posts
196
Reaction score
146
UPDATE: My BCM (Body Control Module) was toast. Everything is back working with a new BCM and reprogram.

I guess the moral of the story is always unhook the battery before unplugging any electrical part; and Never unhook the battery with a component unplugged. (who knew the rear latch assy completes a BCM ground?!?)
I have seen the bcm get toasted because of unhooking the battery while the key is in the on position, that's why I asked. The body control module has a keep alive battery power that kicks in when you unhook the battery while the key is on, it is so that if you get in an accident where the front of your car/truck gets hits hard enough to wipe the battery off or destroy it, the emergency onstar and such can still operate the bcm to unlock doors and communicate with the passengers. It can never be recovered and needs full bcm replacement once it is triggered.
 

Brandon2489

Full Access Member
Joined
Jul 28, 2018
Posts
138
Reaction score
101
UPDATE: My BCM (Body Control Module) was toast. Everything is back working with a new BCM and reprogram.

I guess the moral of the story is always unhook the battery before unplugging any electrical part; and Never unhook the battery with a component unplugged. (who knew the rear latch assy completes a BCM ground?!?)
Awesome! Glad the tsb helped.
 

pwtr02ss

Full Access Member
Joined
Apr 1, 2013
Posts
11,868
Reaction score
25,549
Location
Tennessee
UPDATE: My BCM (Body Control Module) was toast. Everything is back working with a new BCM and reprogram.

I guess the moral of the story is always unhook the battery before unplugging any electrical part; and Never unhook the battery with a component unplugged. (who knew the rear latch assy completes a BCM ground?!?)
Glad you're back on the road. Sucks that it happened though. Thanks for coming back and giving the resolution. It may be helpful for someone in the future
 
Top