2004 Silverado door unlock problem

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by 4wsilver, Jan 24, 2012.

  1. 4wsilver

    4wsilver New Member

    I have a 2004 Silverado, 4X4, crewcab with fairly standard accessories. I have a confusing door unlock problem. I installed aftermarket mirrors to get extension for seeing around a camper. I tested everything before putting the door panels on. Everything worked fine. Passenger door no problem with door panel on, everything still works. When I put the driver door panel on the unlock buttons quit working on both sides. I have leaned the panel out, everything works, put it back in place and doesn't work. It is not binding the door lock because the unlock works from the manual slider and the keyfob. when it doesn't work, the passenger side button doesn't work either. I have looked at the factory drawings and on this model, it appears that the door lock/Window/mirror control assembly is actually a small computer on each door and talks with the body computer via a 2 wire serial link. I have made it happen with the door panel off once by wiggling the harness in the door near the larger speaker but haven't been able to find the spot yet since a lot of the harness moves when I wiggle. I have checked the connectors to the switch, and plugged and unplugged them several times and checked to see that nothing is pressing against the switch. I will note that mine is the YE9 Silverado and the circuit is different from the Non-YE9 according to the factory schematic and doesn't have the relays at the fuse box, that have gone bad in other trucks. The only thing I can think of is that some sort of wiring problem is interrupting the serial link when the unlock button is pushed. The lock, mirror and windows work just fine at all times. If it were only the driver door the problem would be easier, but when it malfunctions both doors won't unlock unless the keyfob is pressed or the manual slider used. Only bright side is that I am getting really good at removing the door panel and switch. It now takes less than 1 minute to do both. Practice, practice!

    I am getting frustrated. Has anyone had a problem like this or have any ideas what to try? I will appreciate any help at all. I have thought about buying a total new harness but am not sure that would fix it
  2. Red Z71 Max

    Red Z71 Max Rockstar 4 Years ROTM Winner 1000 Posts

    It sounds like you have a broken wire in the plug harness. I am thinking that when the panel is in place it somehow quits conducting and is conducting when the panel is off. Check to see if the wires are damaged anywhere visible. This is just my guess but if it works one way and not the other way it doesn't sound like the mirrors are causing the problem. Good luck with the fix!!!
  3. 4wsilver

    4wsilver New Member

    Thanks Red, That is close to my thinking also, but it could be either an open or a short since it is a serial interface. I have inspected the harness for any external damage signs but have not yet cut into it. As soon as I can isolate a portion of it I will start cutting. Usually problems like this are in places where the wires are sharply bent or squished or near connectors and I have wiggled those areas like crazy. I will get my wife to help, she finds everything I lose anyway.

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