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Aux reverse lights blowing fuse

Discussion in '2nd Gen. Tacomas (2005-2015)' started by trdNick, Jan 16, 2012.

  1. Jan 16, 2012 at 4:26 PM
    #1
    trdNick

    trdNick [OP] Odie

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    Hey guys,
    This weekend I installed some aux backup lights on my truck. I went the relay route with a switch in the cab. I did not ground the switch initially and everything worked fine. I grounded the switch this evening so the light would come on on the switch and blew my brake light fuse. I replaced the 10A with a 20A and still blew that :confused::mad:. I ungrounded the switch and everything is back to normal. Any ideas as to what could be causing this. The power for the switch comes directly from the battery if that means anything.
     
  2. Jan 16, 2012 at 4:48 PM
    #2
    AlaskanTaco

    AlaskanTaco Well-Known Member

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    Your relay+reverse lights=to many amps. DO NOT DO NOT DO NOT DO NOT stick a higher amp fuse in line. That is how fires are started! The relay does not need to be that high of an amp. Ohm out from fuse to battery negative. 12v=axr. Amps times resistance/ohms. Solve for a and that is your CURRENT amps. Now do the same thing with the coil side of the relay. Add those 2 together, does it exceed 10 amps?
     
  3. Jan 16, 2012 at 5:09 PM
    #3
    trdNick

    trdNick [OP] Odie

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    I put another 10A in place so I'm good there. I don't have an ohm meter:( But it works fine until the switch is grounded so is the relay the problem?
     
  4. Jan 16, 2012 at 5:15 PM
    #4
    Pugga

    Pugga Pasti-Dip Free 1983 - 2015... It was a good run

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    Are you sure everything is hooked up correctly? I'm assuming the fuse for the brake lights is the same one that powers the reverse lights? The trigger wire for the relay should be the only thing tapped off the reverse light wire and should not blow your fuse. My guess is you have a wire crossed somewhere or plugged into the wrong location on either the switch or the relay. Double check everything! How did you make your connections, solder and heat shrink or some sort of wire tap?
     
  5. Jan 16, 2012 at 5:31 PM
    #5
    trdNick

    trdNick [OP] Odie

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    I used butt connectors but heat shrunk them. The fuse is 1G1, the one where if it blows it locks your transmission. I only have one wire coming off the center wire on my 7 pin connector and it goes straight to the relay and the switch is tapped into that. Is it possible to have the trigger wire and ground crossed on the relay? but the lights still work with both the switch and when I put the truck in reverse so that is why I'm so confused. Would a diode fix the problem? Are the lights sending too many amps back through the reverse wires. Sorry I'm asking so many questions lol
     
  6. Jan 16, 2012 at 5:36 PM
    #6
    Pugga

    Pugga Pasti-Dip Free 1983 - 2015... It was a good run

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    I didn't realize you tapped off the trailer wire harness. Power backfeed could be your problem in which case a diode could solve the problem. Could you throw up a sketch of your wiring diagram? I have a feeling something is connected somewhere it shouldn't be.
     
  7. Jan 16, 2012 at 5:59 PM
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    trdNick

    trdNick [OP] Odie

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    wire.jpg

    i get problems when i ground my switch
     
  8. Jan 16, 2012 at 6:04 PM
    #8
    Pugga

    Pugga Pasti-Dip Free 1983 - 2015... It was a good run

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    It looks like you have power coming in from 2 sides of the switch there. I'll bet if that switch weren't even there, the set-up still works when you have it in reverse, right?
    Check this out, this should help.
    [​IMG]
     
  9. Jan 16, 2012 at 6:06 PM
    #9
    trdNick

    trdNick [OP] Odie

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    sorry that bottom wire is the trigger from the switch to the reverse wire
     
  10. Jan 16, 2012 at 6:08 PM
    #10
    GENERAL OFFROAD

    GENERAL OFFROAD Well-Known Member

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  11. Jan 16, 2012 at 6:13 PM
    #11
    trdNick

    trdNick [OP] Odie

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    yes will work with out the switch. it looks like i need to switch my ground on my relay. Thanks!
     
  12. Jan 16, 2012 at 6:13 PM
    #12
    joes06tacoma

    joes06tacoma Well-Known Member

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    LEER Shell with dome lights operated with 3 way switches, aux backup lights with relay and 3 position switch, modified wiring to compass/temp display and clock to include switch that disables dimming function (poor man's DRL solution), Scan Gauge 2
    Been there, done that. You need to put a diode in the wire coming out of the switch, so that when the truck is put in reverse, the factory reverse circuit won't back feed into your added switch. When the switch is off, the middle terminal is connected to the ground for the light. Instant short.

    There is also a way to do it with a double throw toggle switch (unlighted) and a separate indicator light.
     
  13. Jan 16, 2012 at 6:15 PM
    #13
    trdNick

    trdNick [OP] Odie

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  14. Jan 16, 2012 at 6:17 PM
    #14
    Pugga

    Pugga Pasti-Dip Free 1983 - 2015... It was a good run

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    I think you want to get rid of that spliced wire going from the trailer wire to the switch. Use the trailer wire as the 'trigger' - #86 on the relay. The power from the battery should go through the switch - Battery thru in-line fuse to switch input, then switch output to #30 on the relay. Then #87 from the relay to the lights and #85 to the ground. Ground the switch and you're good to go. When the switch is off, the lights won't come on, when the switch is on, the lights will only come on when in reverse (I think that's what you were going for).
     
  15. Jan 16, 2012 at 6:18 PM
    #15
    trdNick

    trdNick [OP] Odie

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    that sounds exactly what the problem is! where to buy/what is a good diode to use?
    I appreciate the help!
     
  16. Jan 16, 2012 at 6:21 PM
    #16
    trdNick

    trdNick [OP] Odie

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    well i put the switch in to turn the lights on anytime I want/need. So doing this would take away the wire from the battery to #30?
     
  17. Jan 16, 2012 at 6:35 PM
    #17
    Pugga

    Pugga Pasti-Dip Free 1983 - 2015... It was a good run

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    Assuming you don't want to get a double throw switch, I think this can work but you will need a diode so you don't backfeed power somewhere it shouldn't go.

    Use the trailer wire as the 'trigger' - #86 on the relay. The power from the battery should go two places. One wire through the switch - Battery thru in-line fuse to switch input, then switch output to a diode and splice the wire coming out of #87 on the relay (heading to the lights). The second wire from the battery goes through an in-line fuse (or spliced after the other in-line fuse) then to #30 on the relay. Then #87 out of the relay should have a diode also before the other wire is spliced in. That should give you operation where the lights come on every time the truck is in reverse with the option to turn them on whenever you want with the flip of a switch. Disclaimer, it's late and I'm trying to do this in my head :D

    Just doodled it out and I'm pretty sure I've got it right :thumbsup:
     
  18. Jan 16, 2012 at 6:41 PM
    #18
    trdNick

    trdNick [OP] Odie

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    haha I know its late lol:D I will draw it out in the morning! I appreciate all the help!
     
  19. Jan 16, 2012 at 6:46 PM
    #19
    Pugga

    Pugga Pasti-Dip Free 1983 - 2015... It was a good run

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    No problem, I like messing with wiring! Good luck with the wiring, let me know if you have any other questions, always happy to help if I can. :thumbsup:
     
  20. Jan 16, 2012 at 6:46 PM
    #20
    joes06tacoma

    joes06tacoma Well-Known Member

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    I don't really know on the diode. I tried exactly what you did once, had the same problem, went down to Radio Shack and bought some diodes. Never could get it to work. I know I had the right concept, but think I bought the wrong type of diode. I went with the double throw switch and separate indicator light on that truck.

    Ask in the audio forum. It would be the same type of diode used to install alarms.
     
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