Info on trailer wiring ?

[adaviel]

I have a 91 Previa (Canada model).
I'm trying to wire up a trailer hitch connector (US/Canada 7-pin style), and wondered if anyone has any experience with this.
Well, actually, I'm most of the way through the job and was referred to this site from a more general forum, but I'd still be interested.
I found a bundle of unterminated wires behind the left rear light cluster that appear to be what I want, viz.
Green - Tail
Red - Left flasher
Brown - Right Flasher
Yellow - Reverse
Blue - Brake
Black - ??

I'm not sure what the black wire is - it does not seem to be a ground.
I was looking online for some confirmation of this wiring, but could only find a guide to installing a European trailer harness.

[timsrv]

To my knowledge there is no pre-wiring on the Previa for towing. There will be wires going to each light & these can be tapped. There are some differences in wire colors from Canadian to US models, so I won't go into colors. Just pull the tail lights & one by one turn on the lights. Ground is typically white with a black stripe, so the other wire going to the bulb you want is typically the power wire. For the 1157 bulbs you can use a test light to identify the one with power.

One thing to keep in mind is the Previa uses a "3 wire system" & most trailers use a "2 wire system". 3 wire systems have separate stop & turn lamps where the 2 wire systems will use the same lamps for both functions. Assuming the trailer has the normal 2-wire system, you will need a "3-2 wire tail light converter" (http://www.amazon.com/Curt-Manufacturing-58240-Light-Converter/dp/B001EP0GI6/ref=sr_1_4?ie=UTF8&qid=1377839406&sr=8-4&keywords=3-2+wire+converter). The simple converter shown in that link is adequate for trailers with single bulb circuits. If you are towing something that puts a bigger loads on the tow vehicle's electrical system, then it's better to use a "3-2 wire powered tail light converter" (http://www.amazon.com/Curt-56190-3-Wire-Powered-Converter/dp/B004IYB968/ref=sr_1_8?ie=UTF8&qid=1377839728&sr=8-8&keywords=3-2+wire+converter+powered). The powered converter is wired directly to the battery, then uses power from the light circuits only to trigger small relays. This essentially removes the load from the lighting circuit and puts it directly to the battery. This type of module will also give you brighter trailer lights.

If you are towing something that has electric brakes &/or needs a charge line, you will need to add those wires from scratch as Toyota makes no provisions for these. Tim