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Reverse Light Problem

Discussion in 'Truck & Equipment Repair' started by DeereFarmer, Nov 16, 2008.

  1. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    I have some aux. reverse lights on my truck. I wired them up about a month or so ago. Used a 50 AMP relay. Everything had been working perfect until last night when I brought my girlfriend home I noticed that the aux lights were still on. The factory reverse lights were off. Now, I don't have these lights on a switch. I jsut use the stock reverse lights as a trigger. I jiggled the relay a little and lights turned off. Figured problem solved, until they stayed on again later in the night and had to do the same thing. What do you think? Bad relay?
     
  2. theplowmeister

    theplowmeister 2000 Club Member
    from MA
    Messages: 2,551

    I just know it but I'm going to get in trouble for this.....But

    a Relay is a switch

    problem;
    Light stays on :rolleyes:
    fix;
    Jingle relay light goes off.:D

    Repeat.

    Nope I think you have a burnt out Bulb..... Heres your sign:jester:
     
  3. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    All bulbs are good. I checked that first.:nod:
     
  4. snow7899

    snow7899 Senior Member
    Messages: 238

    Where is your relay mounted? I like to install them behind the taillight housing so it is not out in the open. Keep it upright and use lots of dielectric grease.
     
  5. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    I have it right behind the taillight with a good amount of electrical tape. I didn't put any dielectric grease in it and I'm pretty sure it is not mounted upright. Whoops. Beginers mistake I guess. That might be the problem. I bet water is getting in there.
     
  6. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Guaranteed...and will make the relay stick on. Don't pack it in electrical tape as it just holds any moisture that does find its way in there. Make sure it mounted upright, then grease or FF it, preferably both.
     
  7. Rc2505

    Rc2505 PlowSite.com Addict
    Messages: 1,245

    without trying to sound like an idiot here. Why do you guys hook aux reverse lights up to a relay? I have had them on my trucks for years now, and I just hard wired them in without the relay. I have had 0 problems with them this way, and as a matter of fact I haven't even burnt out 1 bulb yet. Maybe I am doing it wrong, but it seems to work fine this way for me.
     
  8. theplowmeister

    theplowmeister 2000 Club Member
    from MA
    Messages: 2,551

    Simple... the revers switch and wire going to your backup lights is sized to handle the current for your stock lights. When you add extra lights you are now trying to get more current through the same wire and switch. what happens is you get a voltage drop through the wire, the result is your backup lights arnt as bright as they could be. If your axillary backup lights are big you can start popping fuzzes and burning out the backup switch or even burning up wires.
    You've been Lucky so far.
     
  9. Rc2505

    Rc2505 PlowSite.com Addict
    Messages: 1,245

    So if I understand correctly installing a relay into your aux reverse lights will keep from popping fuses, and keep from melting wires? I am not arguing just trying to learn. My thought would be all your doing is adding a component that can go bad. By placing the relay in-line your still using higher wattage bulbs which will still allow for blown fuses, and melted wires. The only thing that would save this from happening would be to mount an additional fuse in line after your regular reverse lights, but before your aux lights in my opinion. This is one of those threads that I really like, because I am able to debate my thoughts, and possibly learn something new out of the whole thing.
     
  10. theplowmeister

    theplowmeister 2000 Club Member
    from MA
    Messages: 2,551

    You run a second power line to the new lights (fused of coarse) and use the relay as the switch.
     
  11. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    ..which carries the load of the extra lights....instead of the now undersized factory reverse light wiring that you tacked the new lights onto, and more importantly the reverse light switch..since it's not designed to carry anymore current than the stock reverse light bulbs will ever use.

    The reason some guys get away without the use of a relay is on a plow truck is you may be in reverse often...but not for long periods at any one time.

    But regardless it will shorten the life of the switch. If you've ever seen the contacts inside one of these switches it would amaze you as to how they work as long as they do. :eek:
     
  12. Rc2505

    Rc2505 PlowSite.com Addict
    Messages: 1,245

    You just got to love this stuff. See I have learned something new, and will take heed to that. I appreciate everyones input. Now I have to let you all go. I have 3 trucks to install relays on. Thanks again
     
  13. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    Trust these guys Rc2505. They know what they are talking about. I run four 55 watt aux lights in sequence with my stock reverse lights. All the lights are much brighter because of the relay and a lot safer. I just don't want anything to break at 3 AM and have NO reverse lights. It just gives me a little piece of mind and that's why I run a relay. That and it is more efficienct and brighter.


    As for my problem: I replaced the relay and mounted it upright this time. I coated the prongs heavily in dielectric grease. Everything is working perfectly now. I didn't use any electrical tape which was a first for me lol. Are you sure on that B&B? I trust your opinion, so that's how I did it.
     
  14. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Yep, forget the tape...causes more harm than good once the moisture gets under it.

    One thing that I have tried before as far as relays go is to dip the entire relay with attached wires into a can of Plasti-Dip...been working very very well so far. Especially considering where the relay is mounted...it's on a headache rack right out in the weather every day. Was more of a test than anything but so far I'm impressed after 2 years without a problem. After this season I'm going to cut the coating open and see how it looks inside.

    I suppose you guys know you can buy weather proof relays as well? Lots of on-line electrical outfits sell them.
     
  15. Rc2505

    Rc2505 PlowSite.com Addict
    Messages: 1,245

    Ok so I installed the relays on my reverse aux lights today. Again thanks to everyone with the advice. So I have another question that pretty much relates to the subject. I also have a pair of aux clear lights mounted on the sides of my salt spreader. Since the power wire runs from the battery to the switch in the dash, then out to the lights I do not need a relay for that right? all the wire is new wire that I ran through the frame of the truck and through the firewall, so nothing else is running on this circut.
     
  16. 02powerstroke

    02powerstroke PlowSite.com Addict
    Messages: 1,188

    How big are the lights ? and how heavy duty is the switch? I have run thows rubber Grote lights you get at napa threw just a switch many times with out a problem because they dont draw to much and I used a heavy duty switch. If its a larger 55w off road style light you may want to think about a relay and make sure its fused near the battery reguardless of how you have it wired.
     
    Last edited: Nov 17, 2008
  17. theplowmeister

    theplowmeister 2000 Club Member
    from MA
    Messages: 2,551

    Ya you need to fuse ALL POWER LINES (except battery to starter and alt to battery). a relay is used to switch High power with a low power source. Perhaps youve herd of a starter solenoid. one thing a starter solenoid does is switch the 300 amps that the starter motor uses with your 5 amp ignition switch.

    If your switch is rated to carry the power of the side lights and the wire is big enough to carry the power your all set.
     
  18. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    I'd put a relay in for those as well. You can probably be fine without one, but you've got most of the work done by having the wires run already. I'd just finnish what's left.:)
     
  19. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Run the ground for the relays trigger circuit through a switch. So you can turn the lights off when you don't need them. The positive lead that comes from the back up lights( when on) powers the positive lead of the relay. The switched negative lead is the negative side of the relay trigger. By using the negative lead for switching you can run a light duty wire to the cab and it's not a HOT lead.
     
  20. MAR4CARS

    MAR4CARS Senior Member
    Messages: 246

    Best way to protect auxiliary lighting relays is to install the relay under the dash and use the reverse light wire there to activate the relay then just run a 10 gauge wire back to the lights. heres a easy to follow link to a relay wiring diagram . http://www.ado13.com/techs/relay.htm Also use a good quality relay as alot of the ones you buy at franchise auto parts store sold as off road light install kits are junk.Make sure you relay is a minimum of 30 amp capacity and make sure to fuse the power feed wire to it.Oh and i almost forgot try to avoid using relay sockets as they are cheap and melt just put female ends on the wires.If anyone needs help feel free to PM i own an auto repair shop.