# No power to reverse lites



## DrByrd (Jan 1, 2010)

So I hooked up aux. back-up lights on lt. green wire of my reverse lights circuit. i also had a relay and switch with diode on circuit. worked once till i used the switch blew the fuse under the hood. replaced the fuse but now i have no power to reverse lights? ended up hooking up aux back-up lites to lt green wire on 7 pin trailer plug at rear bumper. would like figure why no power to my revers lites at tail lites. could it be at the bussing block at the rear?so I got power at trailer b/u fuse and at b/u lamps but no power at tail lite reverse lamps only using aux back-up lites powered by trailer wiring.


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## jb1390 (Sep 23, 2008)

So you have power to the auxiliary pin on the 7 pin reciever, so reverse lights would come on if you had a trailer connected? Was the reverse light wiring stock for the trailer plug-or did you wire it in aftermarket? What year/make/model truck do you have? If you had a diode wired correctly in series with your reverse lights/switch, then there should have been no way to blow the fuse under the hood. Can you post a schematic of how you connected the aux lights, and show where you have tested for power?


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## stacks04 (Jan 22, 2008)

need vehicle info before i can be of more assistance.


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## DrByrd (Jan 1, 2010)

the truck is a 2005 3500 chevy dura/allison. I am currently using the aux back-up lites hooked up to stock trailer harness.there are two fuses on this cicuit i have found under the hood 1 is b/u lamps for tail lites ( replced this when i blew it and now have power to it and fuse is ok but no reverse tail lites?) the second fuse is also under hood for trailer back-up lites i am currently using at the 7 pin trailer connection tapped into the lt. green wire to power aux. back-up lites. but have no power to tailite reverse lamps. It looks like this circuit has 3 fuses on it two of which i found the third looks to be used just before it goes to auto dimming mirror (the mirror shows temp and direction this seems fine.the only thing is again could this buss bar near the rear of bed have a fuse or fusible link? Recap i have power to both fuses under hood .power to trailer 7 pin connector NO power to reverse tail lites tun signals and parking lites are fine

have at it!


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## DrByrd (Jan 1, 2010)

one other question once this gets resolved any reason i can't just leave aux lites hooked up through trailer 7-pin without relays and swithes lites are 55w xenon bulbs. I figured if you were to power a trailer this should not be any more load?


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## jb1390 (Sep 23, 2008)

When you say no power-I am assuming you are checking this with a voltmeter or test light correct? Is it possible the reverse lights just blew out-and you just need to change the bulbs? I don't think there is a fusible link in that circuit and I highly doubt that it would have popped because the fuse will go long before anything else will.


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## DrByrd (Jan 1, 2010)

I used a test light on the reverse lites and checked the filament on the bulbs as well. I guess I need to go through all the fuses one by one 
also on this circuit is the auto dimmer mirror and it works fine but it just shows that unrelated things can share a circuit. just have to do more investigative work I guess?


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## B&B (Nov 4, 2006)

Did you check for voltage on the light green wire right at the rear junction block? There's more than one as its light green going in and light green coming out. Even if there's an issue with the junction box the input side would still have voltage.

And the difference between powering accessories with the backup lamp circuit and the TRAILER backup lamp circuit is that the trailer circuit doesn't go through the body control module. 

And it doesn't take much to cause damage to it. Hope you didn't smoke it... payup


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## DrByrd (Jan 1, 2010)

First off thanxs for your responses to my dilema, I started going through all the fuses and found the TCB 2A (15 amp) fuse was blown. Working good now


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## B&B (Nov 4, 2006)

Should have been labeled "TBC", Truck Body Controller...aka body control module. Sure it was just a typo on your part. 


Good to hear it was just a missed fuse. BCM's can get expensive when you fry one. Any time you're connecting ANY type of add on wiring to a later model truck it's very important to be sure it done with 100% accuracy and safety. Because there's many things in the system that will not take kindly to excess AMP draw or a short circuit so all it takes is one time for a slip up and bam...something very expensive becomes a paperweight.


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## DrByrd (Jan 1, 2010)

If it's one thing I have found out it's the little stuff that can play havoc. I would have thought when I installed my new boss v that would have been my worst time but as it turned out It went without a hitch. lites and assy. were smooth


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## DrByrd (Jan 1, 2010)

b&b I stand corrected thanxs


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