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Backup lights

Discussion in 'Chevy Trucks' started by robmtl, Nov 20, 2002.

  1. robmtl

    robmtl Junior Member
    Messages: 9

    I own a 1999 chevy 3500
    i would like to add back up lights 35 watts with switch and a relay.
    i found some info on here which is very usefull but not very detailed.
    1. what size relay do i need. (amperage)
    2. the color of the wire under the dash for the backup lights.
    thank you in advance.
  2. Alan

    Alan PlowSite.com Addict
    Messages: 1,393

    For a relay I sue the ones that are available at the parts stores for wiring auxiliary driving lights. Around here they are labeled "Night Blaster". I'm thinking they are rated for around 30 amps, which is way overkill. Tose 35 watt lamps need a bit over 6 amps, so allowing for inefficiency and wire drop, I would thinkt aht a 10 amp relay would work and 15 would be plenty to give a safety factor.

    As for wire color you're on your own. On our 97 the backup light switch seems to be transmission mounted, we haven't been able to locate any wire near the steering column (where they used to be switched) that is hot when the reverse lights are on. Best I can offer is to start tracing with a test light until you find the one and only.
  3. JohnnyU

    JohnnyU 2000 Club Member
    Messages: 2,040

    IF they are going to be mounted on the rear of the truck, then why couldnt you either 1) plug it into the trailer connector, or 2) splice into the harness back under the lights. I wired in a backup alarm and just used those crimp splicers and a lot of tape... just a suggestion.
  4. Alan

    Alan PlowSite.com Addict
    Messages: 1,393

    The stock backup light switch is designed to handle the current draw of two 1156 or equivalant bulbs. I did my original setup by going through the stock switch and am firmly convinced that was what fried it. The current needed to activate a relay is miniscule, the wiring isn't much more difficult, so now I go with relay switching on all installs.
  5. sonjaab

    sonjaab PlowSite.com Addict
    Messages: 1,425

    GUY....I believe GMs with plow prep pkg. have heavy duty
    wiring and relay from factory.
    I have the GM #27 bulletin:
    Backup lamp power feed is a standard feature on all new
    Gm trucks it is protected bya 10 amp fuse TRLRb?
    For full bulletin and info:
  6. robmtl

    robmtl Junior Member
    Messages: 9

    thanks for your input
    my truck is a 1999
    does it also have the heavy duty
    wiring and relay from factory.
    with the 10 amp fuse.
    or is it the 2000 and newer ?
    thanks again.
  7. sonjaab

    sonjaab PlowSite.com Addict
    Messages: 1,425

    ROB, The bulletin does say ALL 99 & up gm trucks!
    Ya might just have to type in the link cuz' sometimes
    it won't work ! Shows all wire colors, fuse #s , etc
    Try just www.gmupfitter.com
    Then search for bulletin # 27...........geo