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How To Properly Wire Additional Reverse Lights?

Discussion in 'Chevy Trucks' started by DeereFarmer, Oct 5, 2008.

  1. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    Don't yell at me! I've done tons of searches on this topic and now this is a very common topic, but I'm a little confused. First my '02 GMC has the factory plow prep package and towing package with the 7 round plug. I also have the factory AUX. light switch. What I want to do is mount two reverse lights under the bumper for added rear lighting. My windows are tined from the previous owner so it's hard to see to begin with. :dizzy: Anyway, what is proper wat to add these lights. I don't really want to wire a switch so they are on when I want. I jsut need them on when the truck is in reverse. Can I just wire them directly into the stock reverse wires with a relay? Do I wire them into the trailer backup lights on the 7 way? I don't have any trailers with backup lights. Is there a easy way to add them into the AUX switch? That'd be pretty cool. What would you guys do?
  2. BigLou80

    BigLou80 Senior Member
    Messages: 558

    I have the same truck and use my aux switch for my strobes. Just pull off the side panel behind the drivers seat and you will find the relay. Sorry I can't be of to much help on how to wire the back up lights although I would just find the wire for the trailer and add a relay
  3. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,993

    If you use the reverse wire from the trailer towing package. You shouldn't need a relay unless the lights have a very high amp draw. Look on the drivers side frame between the cab and bed, there could be an accessory harness there for Gooseneck/fifth wheel applications. Normal for any General 3/4 ton with a tow package. You could splice a longer one onto that with a GOOD crimp fastener. I suggest low temp solder filled heat shrink connector.
  4. yard5864

    yard5864 Senior Member
    Messages: 149

    I just spliced into the 7 pin trailer connector with 2 tractor lights under the bumper and it works great with no problems.

    Attached Files:

  5. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,993

    The 2002 chevy will have a US car connector. While it and the plug you show are the same from the trailer side the US car is a molded two piece part and has no accessible terminals. But the reverse will go to the center
  6. wild bill

    wild bill PlowSite.com Addict
    Messages: 1,239


    here's a quick one just hooked into a 7 wire plug and plugged in at thee hitch ,look in thread any one using back up lights .
  7. ChevKid03

    ChevKid03 Senior Member
    Messages: 505

    I just put a set on the back of my 03 2500HD because of the same reason. I have BLACKED out windows that are extremely difficult to see out of at night when backing up. I ended up purchasing a set of reverse lights from the local parts store. If you have a test light, you can find the reverse light wire and wire the hot one from the new store bought lights to this. Then run a ground anywhere on the frame.
  8. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    Thanks guys. I like the idea of wiring them to the gooseneck plug. Next time I have the truck on the lift I'll have to take a look for that. I've never noticed it before. I do have a test light and pretty much any tool I need.
  9. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Just a tip here for you guys running hi amp backup lights....

    Do not direct wire lights into the stock reverse light circuit that will draw more than 10 amps max without using a relay.

    The stock reverse light circuit is not externally relayed in these trucks and it travels directly through the reverse light switch as well as the body control module...neither of which are designed to handle more than a 10 amp additional load in addition to the stock reverse bulbs on that circuit. Use a relay. :nod:
  10. famouslee99gt

    famouslee99gt Member
    Messages: 68

    I know you said you didn't want to hook them up on their own switch, but I did such on my '99 Z71 and I love that. I like to leave them on when plowing. They are also useful when hooking up trailers or wagons at night, and they'll stay on when you are in park hooking up the trailer. I personally just like having them on their own switch
  11. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    B&B, could you give me a quick lesson on relays? What do I need to buy as far as relays go? How do I wire them up? I'm new to relays and trust your opinion!:drinkup:

    Also, how much harder would it be to run them to a switch? I jsut don't want to drill a switch into my dash and run a wire through the firewall all the way back.
  12. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    A relay is nothing more than a remotely activated hi amp toggle switch that can be remotely activated with a low amp circuit...such as a small toggle switch with a light gage wire...or in the case of reverse lights, the factory reverse light switch. Its purpose is to carry the hi amp load from the power source to the accessory that you want to operate without having to have the hi amp power run through your tripping mechanism (reverse light switch in this case). Relays cab be wired dozens of different ways depending on what your using them for.

    If you search the net you'll find hours of reading and examples of how relays work and what application to use them for. Here is just a couple quick examples I found:



    Relay diagram
  13. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,993

    you will be able to find all the wires required to use a relay with in the goose harness. the power supply, the signal and the ground are all there and readily available. use a diode if you plan to use both a dash switch and shifter to entergize them.
  14. mkwl

    mkwl 2000 Club Member
    Messages: 2,362

    I did this (no relay) with mine- guess they draw less than 10A cause I've had em on there for almost a year- no problems (knock on wood). They are the cheap $19 ones from Northerntool- work well though
  15. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    OK, so I've read a lot on this subject and think I have it down. I'm going with a realy for sure. Let me make sure I have this correct. There are 4 prongs to a realy. One is a hot lead from the battery, one is a ground (more than likely I'll run this from the battery as well just to be safe), one is a trigger (in this case probably run from the stock backup light, correct?), and the final one goes to the load (new backup lights). Now, here are a few more questions I have:

    -to power a pair of 55W lights do I need two relays or just one?
    -what gauge wire should use?
    -on a standard relay how can you tell what prong goes to what function? most relays I've seen arn't marked or anything.

    I'm pretty sure I'm ready to tackle this project. I've done a lot of trailer wiring and wiring for trailer hitches so I do have some experience on the subject. Just don't want to screw up my truck. Thanks guys.
  16. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    You've got it. :nod:

    A single relay is plenty for two 55 watt lights. Most generic relays will handle 30 amps each.

    Use 14 gage for the batt power wire as well as the wires to the lights from the relay. The ground and trigger wires can be much smaller since they carry little current, 18 gage is more than enough. Make sure to fuse the toggle switch power wire (5 amp is plenty) as well as the power wire to the battery (15 amp will do it).

    If you look on the underside most generic relays are marked with the corresponding pin locations. If you get one that isn't you can tell just by the pin orientations if you use one of the diagrams in several of the links I previously posted.
  17. cet

    cet PlowSite Fanatic
    Messages: 7,257

    I know you said you didn't want to use a switch. When I put my lights on my truck I used an ON-OFF-ON switch through a relay. I can have them on all the time, everytime I put the truck in reverse or not on at all. I didn't want them on when I didn't need them and I also wasn't sure how much power they were going to use. If my truck started to get low on power then I won't use them at all. That never happened though.
  18. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    Thanks again guys, especially B&B. What if I want to go way overboard and wire up 4 lights? I have two 35W tractor lights for under the bumper and also two 55W CAT lights that I was thinking of maybe mounting on the top of the bumper right under the stock light housings. It might be overkill, but I'm just thinking. Want to get it all planned out before I start tomorrow. Is there a relay out there that can handle 60 amps? Maybe I'm just nuts. I'm feeling confident about this install thanks to you guys!
  19. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Just add a second relay if you want and use your toggle (or whatever tripping method your using) to trip them both.

    Most Bosch style generic relays like we're discussing here are 30 amp...some are 40. There are relays that will handle hundreds of amps but their under the solenoid classification like a snow plow under hood solenoid (which is just a large relay)...and would be way overkill for your intended application.

    A single 30 amp relay will actually support over 300 WATT but they tend to melt the wire terminals when running too many wires off each pin on the relay.
  20. Bruce'sEx

    Bruce'sEx Senior Member
    Messages: 873

    I've got mine on a switch at the momment, but I'm upgrading to the on-off-on system, i like the idea, and is more flexable for what I need when.