Trailer harness wiring diagram

[Charlie Strobel]

Can anybody provide a wiring diagram for the Tundra trailer wiring harness? Going into the harness are a bunch of wires. Coming out are four (4-pin flat connector). Are any of the wires going into the harness for the backup lights? If so, is this on a relay or just connected directly to the trucks backup lights? Want to install some more powerful backup lights. If this circuit is not already relayed, I'll have to install one for these lights. If it is, I can just tap into this.

Thanks.

[nhparrot]

Electrical diagrams for the 2000 and the 2001 & 2002 models are available in the "Garage" and accessible to Club Members.

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[Tundradad]

The back-up lites are on a relay & I tapped right into each one of them with 55 watt fogs & works perfectly " " superman" came up with this way & several others I know have done this with no problem. I used a set form Walmart, called "Navigator" that are very slim w/ alum hsg. Metal bracket slides in between chrome bumper & real bumper, between two bolts. Tighten the two bolts. done. simplest way to do it. $39.00. Comes with remote sender & seperate switch, and bunch of other stuff I didn't use..

[Mudog715]

Originally posted by Tundradad
The back-up lites are on a relay & I tapped right into each one of them with 55 watt fogs & works perfectly " " superman" came up with this way & several others I know have done this with no problem. I used a set form Walmart, called "Navigator" that are very slim w/ alum hsg. Metal bracket slides in between chrome bumper & real bumper, between two bolts. Tighten the two bolts. done. simplest way to do it. $39.00. Comes with remote sender & seperate switch, and bunch of other stuff I didn't use..

Yes, they are on a relay HOWEVER the power source for the relay (and backup lights) is the same 10A fuse as the Gauges ("Gauge" fuse)... not enough for a pair of 55w lights, the stock 27w lights and the gauges and a few misc. things that also get power from that circuit. Also, the stock wiring for the backup lights from the relay (under dash on LH side) is only 18 gauge, way too small for additional high-power lights. Look at youe Voltmeter the next time you shift to reverse -- note the pretty substantial drop on the gauge? That's because of the voltage drop the added load places on the Gauge circuit.

To summarize: running extra 55w lights directly from the backup lamps circuit is NOT recommended. It may work for a while, but in the long run it will blow the Gauge fuse (another member already learned this).

If you have the factory tow package, there is a 20A fused battery feed already at the rear of the truck (at the black or grey 7 pin trailer converter plug, on the LH side under the bed, I think its the BLK wire, one of the center pins). Mount a relay back there. Connect relay pin #87 to this battery feed, #30 to the lights (+), #85 to ground and #86 to the backup lamps circuit wire at the trailer harness plug (the plug under bed, just behind the license plate). These pin numbers refer to common Bosch automotive relay terminal markings. FYI, The reason I have the bat feed to #87 is because if you reverse them, pin 87a would be hot all the time whenever the backup lights aren't on and could potentially short out.

[Charlie Strobel]

Thank you all for for helping me out on this. You've been a big help.