need help hooking up aux back up light relay, which wire powers the back up lights?

[riceandpho]

i think the black wire might be constant or hot with key on.dont really need the relay to have a constant hot for reverse light, even hot with key on is fine, dont think your leds will draw alot of power.

i did something similar to this
http://www.piaa.com/Shared/instructions/1500 Backup.pdf

 

[Ed_C]

i thought that was self explanatory, they are aux backup lights so they only come on with engine running when you are in reverse. so i already have a working relay wired into the backup lights wiring and now i am trying to find a power source to run through the relay to power the lights

In his defense you did say "constant power", which usually means powered even with the key in the "off" position.

The black wire coming from the small black connector is what you want to tap into to power your relay. I did the same to power a relay for a auxiliary HID reverse light on my parents' GX470 (also uses a 7-terminal trailer connector). Instead of tapping directly to the vehicle wiring I used a universal trailer connector like this

 

[BagiMT]

There is really no need for a relay unless you run power from the front. The yellow wire is for reverse lights on the trailer so you can power the lights from there. Ground is the white wire or easier on the body. That's how I wired mine.

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[Ed_C]

I used a relay because the HID ballast I powered drew almost 10 amps at startup;the reverse light wire is connected to the 15 amp IG1 circuit which already powers multiple circuits so I didn’t want to risk overloading it. The black wire is powered by an independent 30 amp circuit.

 

[keakar]

I used a relay because the HID ballast I powered drew almost 10 amps at startup;the reverse light wire is connected to the 15 amp IG1 circuit which already powers multiple circuits so I didn’t want to risk overloading it. The black wire is powered by an independent 30 amp circuit.

exactly, the wires for the backup lights are 20 gauge wires and it would melt down the wiring harness causing massive problems if you put 5 or 10 amp power draw through those.

adding a relay costs less then $10 total including the extra wiring so why risk destroying your rear wiring harness and possibly have a melt down?

i am not sure of the power draw on my aux LED lights but it is not the same as just adding an LED light bulb to an existing light fixture.

There is really no need for a relay unless you run power from the front. The yellow wire is for reverse lights on the trailer so you can power the lights from there. Ground is the white wire or easier on the body. That's how I wired mine.

Sent from my Fire Phone using Tapatalk

i didnt realize the 7 pin plug had a designated backup light wire. i hadnt even thought about it before but i guess campers do need backup lights. had i known this then you are right, using that wire directly means there is really no need for a relay because it would be sized for running normal incandescent bulbs and would have had adequate power to run the aux LED lights and that would have greatly simplified things :doh: