NEED HELP 04 Chevy Trailblazer Electrical Issues

[Trailblazerguy]

Need help on my car. 04 chevy trailblazer lt 4.2 4wd. Last time i worked on it, i left all the doors open and the back hatch open for hours on end. Well at the end of the night i just shut them and went to bed. Next day i went to start my car, it stumbled at first but started up like normal…. Except for the guages. I only have a tachometer and a check engine light, nothing else. So i tried to plug my obdii scanner in, well it powers up through the obd port, but there’s nothing there. Like i have the light to know its getting power, but it won’t connect to the cars computer. Fast forward to now a few days later of driving it like that, today, I disconnected the battery for 35 minutes and put a new battery in and nothing has changed, except now my door locks aren’t working either so my tailgate is locked shut and i cannot access it. Info center says Unknown Driver and nothing in the vehicle works except the tachometer. Ignition switch works perfectly fine and was tested with 2 different new ones. Ive checked every fuse with key on and off. I’ve checked back hatch wires, I’ve tried it all. Please help me

 

[Trailblazerguy]

Got back hatch open, but still no door locks/windows or any change in the electrical issue. Just was able to manually unlock the hatch from the interior.

 

[mrrsm]

If you are in Freezing Very Low Temps... Visit your Under Hood PDC (Power Distribution Center... AKA ... Fuse Box) and TIGHTEN DOWN The Four Galvanized Fasteners that hold the Wire Harness Under-Blocks up close and personal to the Fuse Matrix inside and see if that makes any difference:





Then… Check your Engine Block Grounds VISUALLY with a Bright Flashlight and R&R them and clean them until all contact surfaces SHINE, Then re-attach them with a Dollop of Dielectric Grease in between to discourage further Galvanic Corrosion:



See @Realism ‘s Epic Grounds Thread HERE for more imagery and grounds location Data:

Thread 'Electrical Ground locations'

May 20, 2016

While troubleshooting a bad ground I came across some scans of the service manual regarding electrical ground locations for our platform posted on another site. This includes both short and long wheel base, as well as both 4.2L and 5.3L.

Credit goes to Wex. http://forums.trailvoy.com/showpost.php?p=1019927&postcount=2

*Note that ground locations may have changed from early to late model years


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• Realism
• Replies: 18
• Forum: Technical Discussion

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[Mooseman]

The interior lights are controlled by the BCM and would normally turn them off after 10 minutes or so. The battery shouldn't have been affected. The fact that you put in a new battery says this is not the problem.

Electrical gremlins are often caused by a flakey ignition switch. Check its operation and replace if required. This video, queued at the right place, explains how to test it with just a test light.

UNKNOWN DRIVER message and the lack of BCM controls working tells me either power is not getting to it, the network is affected or the BCM is damaged. The fact you can't get a scanner to work tells me the network might be dead. That could be a defective module pulling down the network.

 

[Mooseman]

Further reading on how to diagnose a module pulling down the network:

Thread 'Unknown Driver'

Jun 27, 2013

This will be long, so please bear with me.

I was doing some grocery shopping earlier tonight and decided to make one last stop. I jumped back in my car, started it up, and left the parking lot. I was cruising about 30 when first my ABS and Brake lights lit up. About a second later my DIC stated "Unknown Driver". Then all the lights started going crazy on my dash. I decided to pull over ASAP and shut if off thinking maybe it needs to restart or something. I started it back up but all the gauges were still messed up and lights were lit up. Here is a picture of what I saw...

• dfc739
• Replies: 14
• Forum: Technical Discussion

 

[TJBaker57]

Last time i worked on it, i left all the doors open

What were you working on that last time?