Chevy electrical issues

[35Remington]

EDIT: Problem solved. Mega user error.

Alright, let's see how we do with electrical diagnosis on TGT. 2004 Z71.

Yesterday I took both front door panels off to inspect the speakers since I'm considering an upgrade. I completely removed the interior door panels, including unplugging the window and door switch harnesses. Now that I have put everything back together, the only thing that works is the passenger window switch. Everything else is dead. Driver and passenger door locks, driver window switches, and mirror switch. All not working. The other thing that does not work anymore is when I used to move the transmission from Park to Drive, the doors would lock, and vice versa. That's not happening anymore either.


Of course I pulled the panels again and made sure the harnesses were in the right place, and plugged in correctly. I disconnected the battery and checked for fuses under the hood, and in the two places in the cab where there are fuse boxes. I did not see any fuses that directly said "window" or "door lock," but I inspected most fuses anyway and found nothing blown.

When using my Autopage alarm clicker, the doors still lock and unlock just fine. I am completely stumped and need some help.

 

[shortround]

Sounds like you messed up the body control module when you monkeyed with the electrical harnesses.

Find a shop with a GM scanner or head to the dealer to have him scan the car's computer.

 

[35Remington]

Sounds like you messed up the body control module when you monkeyed with the electrical harnesses.

Find a shop with a GM scanner or head to the dealer to have him scan the car's computer.

Yikes. I don't know what a body control module is, but they don't sound cheap.

 

[Brains]

BCM is most likely fine, more likely something with the driver door module (integrated with the window/lock switches). Often times it can be reset by removing power for a while, but it that still doesn't work you may have messed up the wires as they pass between the door and the jam (kinda common when you're tugging things around).

 

[mitchntx]

IIRC ... all power for both sides run through the driver's side switch assembly.
Sounds like power is dead before it gets there.

The door harness also has a connection behind the lower kick panel.
Maybe it was pulled loose when jockeying the door cards.

Second, I would look for a bad ground.

Third I would look for a chaffed wire as it goes through the A-pillar.

The auto-lock feature wouldn't work if there is no power to the lock switch at the door.

Electrical gremlins drive me insane.

 

[35Remington]

Thanks for those responses so far. Are y'all's suggestions consistent with the fact that the remote is still able to lock/unlock the doors just fine, and the fact that the passenger-side window switch is working fine?

 

[Brains]

The good news is if the remote works, the BCM and the DDM are working. Modules in these vehicles are VERY robust - its very rare for the main modules to fail. Since the remote is working, then I would wager a guess there's something wrong with one of the wires going into the door, with a hunch it's one of the data lines.

These might help:

 

[Byrd666]

Just a thought but, have you completely unhooked the battery for about a minute or three, and let the computer reset it's self? Worked on my older, 96, GM when I had a glich in the headlights.

 

[35Remington]

Thanks again, boys. I appreciate the participation. I'm a member of two Chevy forums, and not a single response to my same post over there. I love how active TGT is.

Brains, I have a multimeter. Would that help? What do I turn its big dial to in order to test these wires?

Byrd, I have, thanks. I tried unplugging for over 2 hours with no luck.

 

[hink]

The BCM is good, since your doors still lock using the aftermarket control. The door lock controls work on a databus system that uses the driver's door control as the master, with all other controls as slave controls. If none of the door locks work, it's either the BCM or driver's door lock module. Since you had the door panel off (and I'm assuming it worked before without issue) then I'd suggest you pull the driver's door panel back off. Check that the connector is seated. If everything looks good, then unplug the connector and check the pins - you may have bent one or more when reconnecting the connector. If that's the case, bend it back carefully with needlenose pliers.

 

[Leper]

Sounds like a pin got pushed out of one of the connectors, or is just a bit loose. Look for a wire that is slightly pushed out, while everything is connected. Also you could squeeze the back side of the connectors and try using one of the non working switches at the same time. That would let you know which connector has the loose wire.

 

[35Remington]

... [Y]ou may have bent one or more when reconnecting the connector. If that's the case, bend it back carefully with needlenose pliers.

You know what, I bet that's exactly what happened. It makes so much sense now that you say knocking one out would kill both.

 

[35Remington]

Well, I have great news and bad news. The bad news is I didn't fully connect one of the driver's side harnesses, which meant it disconnected once re-seated on the door panel. The great news is when I discovered that today, and plugged it back in, everything began to work again.

Sometimes it's the simplest things...

Thanks, everyone.

 

[hink]

No worries - glad you found it, fixed it, and have it all working again.

I'll put it on your tab.

 

[Brains]

You said it - sometimes it's the simplest things. Most often, in fact. I'll mention it again, since so many people are so quick to blame electronic modules - the modules nearly NEVER fail. It's nearly always something else, and more often than not something very low-tech.