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GM Auxillery Light Switch

Discussion in 'Chevy Trucks' started by DozerMan, Jan 14, 2010.

  1. DozerMan

    DozerMan Junior Member
    Messages: 21

    I have a '02 Ext cab with the Duramax and snow plow prep package. I've had a Boss V plow for several years, and the truck/plow light switch is mounted separately. My factory auxillery light switch is not being used.

    I would like to add some LED back-up lights on the rear of the truck, and I was wondering i I could use the factory auxillery light switch to control the new lights. Has anyone done this, or does anyone know how to tap into the switch? Also, is it just a switch or does it have wires leading somewhere?

    Thanks for any info!
  2. jdknight75

    jdknight75 Senior Member
    Messages: 106

    the wiring for the aux switch is in the headliner over drivers seat and yes you can put your lights on this switch
  3. cubanb343

    cubanb343 Senior Member
    from ERIE
    Messages: 637

    I have an ext cab, and have two cheap lights on my backrack wired to that switch. I ran the wires out the third brake light.
  4. Maine_Train

    Maine_Train Senior Member
    Messages: 462

    There are a few other threads here that have links to the GM Upfitters site, where they have diagrams to help you locate the wires, color codes, and other info. You can look it up by year and model. The plow package light setup includes a relay, probably located nearer to the floor.

    If you run rear lights off that switch, you'll have to turn the little symbol on the dash around so it'll work right. :jester:
  5. bike5200

    bike5200 Senior Member
    from Ky
    Messages: 437

    The wire is above the headliner, on my 01 I found the wire in the post and use it to operate my strobes. The switch in the dash works a relay in the post behind the seat, I have a regular cab. Make sure you get the wire that the relay switches.
  6. fortywinks

    fortywinks Member
    from NE OH
    Messages: 82

    Part two..

    Couldn't start my 2007 2500Hd yesterday after I had already started it twice that day. Jump started it and drove it to work. Sat all night and started right up the next morning. Took it to the dealer and the tech says the auxiliary switch was on and drawing power. I said horses**t I don't ever touch the switch, I use a magnet mount/cig. lighter setup. He said the switch was on and drawing power. What would it be powering? The truck is off and no keys in it. It completely discharged in 3-4 hours and wouldn't start? Dealer said the switch is connected to a module that powers other devices in the truck. OK fine, but truck was off. Dual batteries check out OK as does alternator. What else should they/I be looking for?

  7. 04chevy2500

    04chevy2500 Senior Member
    Messages: 228

    that switch will work even when the truck is off. if the truck is off then the light wont show that the switch is on. right next to the switch though their is a light that will light up when the truck is on. as far as i know nothing else is wired into this. at least it wasnt on my 04. it will draw though if left on.
  8. andcon83

    andcon83 Senior Member
    Messages: 388

    My 3 year old turned it on with nothing hooked to it....battery dead flat next morning.
  9. Maine_Train

    Maine_Train Senior Member
    Messages: 462

    I wonder if having it on draws current by "pulling the relay down" even though the relay isn't flowing power to anything else. :confused:

    I just went out and checked mine after reading these last few posts. There was an air freshener hanging in front of the indicator light, so I wanted to be sure I hadn't left the switch on. (I had experimentally pushed the button a couple of times the other day, even though I don't have anything connected to it yet.) The switch was off, so I eliminated one possible cause of the "no-juice condition" I've been seeing off and on for the past few days.
    (My prime suspect is the FishStic being lit up all the time, even with the key off, although that seems like it would be a very low draw.)
  10. andcon83

    andcon83 Senior Member
    Messages: 388

    The Fishstik should shut off. Mine does. Does it stay lit up with the plow unplugged?
  11. Yup, that will do it. It took me quite a while to figure that out. If the plow is attached to the truck and the fishstick is on all the time it activates one of the relays in the isolation module and holds it in which will kill your battery. Move the red wire from the controller harness to keyed power and your problem will be solved.
  12. Maine_Train

    Maine_Train Senior Member
    Messages: 462

    Dunno yet; I've only had the MM2 off the truck once since I got it in mid-December. I don't think I ever looked at the controller during the week or so that the plow was unplugged. If Wednesday's forecast of snow turns out to not be much, and nothing big seems to be coming for awhile, I'll probably take the plow off again. Then I'll make sure to see if the light goes out.

    Ah ha! This afternoon, I got it started and ran my errands, then when I got home, I unplugged the Stic before I went in the house.
    At least it "went flat" in my driveway, with an extension cord right handy for the charger, because my portable hotstart box hadn't been charged for awhile. It was providing juice, but not enough to start it.

    Thanks for the info.
  13. fortywinks

    fortywinks Member
    from NE OH
    Messages: 82

    I haven't touched that button in probably a year or more. No need to. So I rule that out as a cause. The service rep said it was "barely on" and it doesn't take much to move it. Look at your switch and figure out if its anatomically possible to accidentally brush that button. Plus I had already started the vehicle up twice that day. Both times I only moved it 50 feet or so, but no hesitation either time. About 4 hrs later, zip, nada. I go to pick it up in the morning and hope to talk to the tech about the whole thing and get his input directly. Just in time because we're expecting 6-10" of snowfall next 24+hours.

  14. If you want to get the absolute AHA! moment, when you take the plow off, open the hood first and with the controller plugged in and the truck off, unplug the 11 pin harness first and listen for the relay to click in the isolation module. There is your draw. Hopefully you haven't killed the long term life of your battery.
  15. Maine_Train

    Maine_Train Senior Member
    Messages: 462

    Yeah. It's got duals, and I think both were new when I got the truck, and the main battery was having problems even after they replaced it. After the truck "sits" for a day or two, it might not want to start when I'm ready to go somewhere. :mad:
    Maybe this afternoon I'll take a ride up to the Fisher dealer, and see if the power feed is on the "keyed" side.

    I might have to start a new thread for this, but there's probably already one about this same situation.
    Thanks again for the info.
  16. If the fishstick is lit up all the time, it is not keyed and thats your problem. No need for a new thread.
  17. Maine_Train

    Maine_Train Senior Member
    Messages: 462

    I didn't want to hijack the thread, but I imagine DozerMan not only got the info he wanted, but by now probably has his light(s) all hooked up, too. :D

    Even with leaving the FishStic unplugged when I shut it off at home, I went out there this afternoon and had to jump it. The plug-in charger/booster is supposed to supply 40 amps for starting, but it was kinda balky on the first try after I hooked that up. (Dang side-mounted terminals.)
    I just went out and put it on the charger. I think I got a good connection on the terminals this time, because the ammeter swung right up to 9+.

    If I leave it on the charger tonight, that will probably ensure we'll get some snow that was otherwise going to miss us. :rolleyes: