'07 Tahoe Electronics Failure after Battery Connection, DESPERATE!!!

[WillySLC]

First time poster. Nicely managed forum!!!

I have done searches and quite honestly my problem now scares me to death.

Summary: I was installing an after market radio upgrade for my '07 Tahoe. Part of the procedure was to disconnect and the negative battery terminal. After doing this, most interior electronics failed (lighting, won't start, door locks etc). Searching indicates likely Body Control Module BCM issue.

Things we've done:

Borrowed pro grade scanner from auto parts store. Returns code U0140, Failed to communicate with BCM.

Attempted BCM reset: Key to Start back to ACC on wait 10 minutes; Key off, ACC wait 10 minutes; Key off, ACC wait ten minutes; Key off attempt to start. Starter motor does not run at all. Repeated this process 3 times.

Reinstalled factory radio and tried reset procedure above, same result.

Please note: theft deterrent light is no staying lit, so don't suspect theft deterrent issue. Although, above reset procedure should have cleared that.

Upon turning key to on position, dash indicators appear relatively normal. Nothing obviously stand out. However, Service 4WD warning and one other appears.

Having read several posts on this forum for unsuccessful dealer visits to fix BCM issues, have I just sacrificed my Tahoe? Are there any success stories out there?

The irony is that I have LOVED this car for several years now and was committing to several more by attempting to upgrade the factory radio. Now I may have torpedoed those hopes.

Thanks for any help.

 

[iamdub]

Checked the BCM fuse(s)?

 

[NathanJax]

There's a huge issue with the negative battery wire...

Also, have you tried a new bcm?

 

[WillySLC]

Checked the BCM fuse(s)?

Yes sir. BCM Fuse OK.

There's a huge issue with the negative battery wire...

Also, have you tried a new bcm?

I've seen posts about the negative battery wire. The rest of the car does not seem to have any issues. Mainly things run by the BCM. Considering new BCM, but trying to exhaust all options before paying $$$$$$$$ for that. More efforts tonight. Meanwhile it sits DIP (Dead In Place) in my sons garage.

 

[Doubeleive]

hmm, these students ran into a similar problem, you might give this a read and maybe try completely disconnecting it and let it sit for a little while and try it again? I don't know just an idea
http://www.iatn.net/forums/2/317236/what-would-you-do-no-communication-with-bcm

 

[Doubeleive]

Most common affliction for this is corrosion on the contact pins. Disconnect B+ cable at the battery ( While there check the fusible link for green stuff, BCM is fed through this fusible link ) Then disconnect cables from the BCM and re-seat them a few times to scuff and clean the contacts. Put everything together and try to start your Tahoe. If this doesn't work look for a broken or chaffed dark green wire. ( GMLan )
https://www.dropbox.com/s/szpu3sckav045c9/2007 Tahoe BCM.pdf?dl=0

 

[Doubeleive]

more possibly useful information
http://www.automotivetroubleshootingsecrets.com/2008_GM_truck_network_protocol.html

 

[OptCodeVoid]

Any chance you could take some pictures of your radio wiring? Its odd that a simple radio install could mess up a truck so bad but we need to look at where the problem started and not where it might be... Another question is what is working? If anything...

Modern vehicles like this put a lot of stuff through the radio (stupid IMO), com lines and the such, a simple short could cause all sorts of odd issues in the electrical system. With that being said I feel like some details are missing but I will poke around the diagrams I have and see if I can give you a direction to start in.

 

[swathdiver]

A Tech2 would be mighty handy for you right about now. Who do you know that has one?

 

[Michael1972]

Hi,

not sure how handy you are, but here is what I would do:

*Reset the car install- all changes you have made so far, to prior condition.

*Disconnect pos battery terminal, connect 12V Testlamp- or any 12V bulb, accross removed pos connector and batt neg ( to discharge residual energy)

*Let it drain for 10min

*Connect the pos connector to battery -BEFORE- you do this, connect the 12V light bulb in series ( it will light bright and reduce the brightness within 2-3 seconds), this will charge all ECUs without high inrush current.
When light ist almost off, connect instantly, while bulb is still on, the pos terminal to battery.

*The BCM com. still not working? Get BCM connetor, and measure the voltage on the BCM terminal with voltmeter - (sorry, have no pinout of your BCM, you have to look it up yourself).
Make sure you have: pos, neg and switched pos.

Hope there you,ll find your issue.

Good luck and a great 2018

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