Hello. Sorry, this may be a long post...
My son just bought a 2008 Silverado, Crew Cab, 4.8l, 4x4. When he bought it I noticed that the door locks looked weak. They would all work, but the front doors did not look like they were moving with a lot of power. The passenger window switch would only go up and felt physically blocked from moving down (this was an easy fix though as I pulled the door panel and switch out and there was a small pebble stuck in the switch. Works fine now).

We removed the stock radio and installed a new stereo. Just installed a new head unit (no amps or anything fancy) and I used store bought wiring adapters with the harness to maintain the chimes; I didn't try to re-wire it by hand. Stereo went in fine and works correctly.

After the stereo was installed the passenger side power door lock stopped working. When you use the switch it will unlock the rear doors, but not the fronts. A short time later the drivers door power lock stopped working. It will also do the rears (not the passenger door) but the lock for the drivers door moves a bit, but won't lock or unlock. The drivers side control for the passenger side window also stopped working. It will work intermittently if you jiggle it.

I have removed the passenger side lock actuator and it works manually. I put my multi meter on the switch. Where the plug goes into the switch at the button there are 4 wires (2 blue, black w/stripe and black). I get just shy of 12v with the blues constantly. Nothing form the black w/stripe.

At the actuator there are 4 wires, but they are orange, peach, orange w/stripe and black. I get no voltage to any of these either sitting or using the switch.

I swapped the switches from the front doors and nothing changes, so I am confident it is not just a bad switch.

I have checked fuses and don't see anything wrong. I have tried jiggling things to find a cracked wire. Nothing.

So my questions are: is it likely that the actuators both fizzled out at the same time? Could the stereo install have anything to do with this? Like i said, it went in fine and no other issues or warnings came up and no codes. Suggestions for things to test?

I do my own repairs and know my way around a car, but I'm not a professional mechanic. Electrical is not my strong suit, so please don't be too technical or you'll lose me!

Thanks for any help!
Steve.

 

it's such a common problem on this forum ... power locks and windows going out. Every week. If you did a keyword search, you probably would have seen me post this a dozen times before .... 90% of the time it's wiring in the door harness. They get bent back and forth, every time you open and close the door, over and over .... and eventually break. Sometimes the switches develop dirty/corroded contacts. Depending on the user, they get exposed to the outside elements and human hand buildup lets call it. But it sounds like you tested the switches and solenoids, so I'm going to go with wiring.

 

Thanks for the reply. I appreciate it. I did try and search the forums and did see a lot of lock/window issues but they didn't seem the same, especially with the stereo install part. It seems unlikely but part of me wonders if that could have screwed something up. Like I said, electrical is not my strong suit, but I do know that all sorts of weird things run through the stereo, like chimes etc. and want to rule that out before I move on. Especially since both front doors seemed to go a bit haywire near the same time.
I will look at the wires again and see if I can find anything.
Should there be a constant 12v at the actuator harness like there is at the switch end? That, to me, would suggest a wire issue.
Thanks again for taking the time to reply. Much appreciated.

 

I can't think of any reason for the head unit to affect locks/windows.

As for power flow, I don't know off the top of my head. If you haven't already, grab a Haynes/Chilton manual with the schematics. They're only about twenty bucks. Incredible value for the money if you ask me. Saved me hundreds if not thousands.