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Door locks, I hate you!

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by janikphoto, Sep 25, 2012.

  1. janikphoto

    janikphoto New Member

    So, my door locks work with the alarm remote. This tells me it isn't an actuator on any/all of the doors, since they WILL lock and unlock. However, none of the lock buttons inside the 1999 Suburban will work. The doors still lock and unlock when the ignition is turned on and off, but the buttons don't work at all. It means that I need to completely turn off the truck to get something out of any of the other doors. It's annoying. I thought I checked all the fuses, and I didn't see one that was bad. I went to a junkyard, and they were nice enough to let me try their switch before I paid for it. Nope, a different switch did nothing. Thoughts???
  2. BoneHead

    BoneHead New Member

    Loose wire?? I wish I had a wiring diagram I could share. Not sure where they go from the switch. There's got to be some kind of box, or relay where the inside switches and the alarm meet to send the signal to the actuators. Not sure where it would be though. At least that's where I would start looking if I were in your shoes.
  3. Pikey

    Pikey Moderator Staff Member ROTM Winner 1000 Posts

    Check the relay. Most alarm systems require separate relays to be installed to work, that would explain why they work with the alarm and not the switch.
  4. janikphoto

    janikphoto New Member


    Good idea. Any thoughts on where the door lock relay is located? I'll just switch it out and see.
  5. Pikey

    Pikey Moderator Staff Member ROTM Winner 1000 Posts

    I found this:

    The polarity-reversing relay is located under the driver-side dash and is mounted by a push-through keeper to the circular, raised section of the firewall. Put your steering wheel in the highest position, lie on your back with your head under the dash. Then as you (or someone else) activates the door lock switch on the driver door controls, listen and feel until you can "feel" the clicking from the relay. It is a black, relatively flat, component about two inches wide and two inches long and attached to the electrical system by a multi-wire plug.

  6. Pikey

    Pikey Moderator Staff Member ROTM Winner 1000 Posts

    Did you get it fixed?
  7. Crawdaddy

    Crawdaddy Moderator Staff Member Platinum Contributor 1000 Posts

    I'm not so sure it's the relay. If the locks are working at all, in both directions, then the relay is working fine. The power locks can be a very tricky thing to diagnose. The lock and unlock signals go through the courtesy module and the alarm module. To date, on the 99 pickup, even after tearing apart the entire dash, I have never found this "courtesy module" that so much of the electrical wiring goes through.
  8. Pikey

    Pikey Moderator Staff Member ROTM Winner 1000 Posts

    You could be correct. the last alarm system I installed in a 97 silverado required an extra set of relays to be installed for the door locks to work from the alarm system. So, stating that he should check the relay, I was referring to the original oem relay not the alarm relays. His alarm could be completely different from the one I installed and I could be way off

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