Wiring for running, brake and turn signals, for flat towing, behind tow vehicle Options

[DanT]

Anyone done the clean set up of actually tapping into the existing wiring or harness to run turn signals, running lights, and brake lights?
Running these off the tow vehicles lighting circuits. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)
I am sure it can be done, just want to know if anyone has gone here before.
If so how did you do it, what does your wiring diagram look like?
No I am not interested in aftermarket magnetic tow lights.

Thanks

[racergreg]

Because it was easier, I tapped into the wires in the trunk, right next to the lights. That also provided a convenient place to mount the diodes, right to the trunk floor. (This is a track only car, so it's stripped out.) I then ran the three towing wires into the engine compartment and then up the tunnel with the rest of the harness. Then behind the pedals, through the hole behind the fuse block, and into the front trunk.

It could probably be done at the fuse block, but I found it to be easier the way I did it. It's such a crowded mess around the fuse block, I didn't want to get involved with it.

Yes, the diodes are specifically designed for this application. They are sold to RVers who are flat towing a car behind their rig (which is what we do!). I'm sorry I don't remember the price...not cheap, maybe $10 apiece or thereabouts. There's actually two diodes in each unit, in a "Y" arrangement.

The wiring: each diode has two "in" connectors and one "out." I cut the wire going to each light. The original wire from the fuse block/switch gets plugged into one of the "in" connectors (I crimped on a spade connector). The wire from the towing rig gets plugged into the other "in." I then made a new wire going from the "out" on the diode to the bulb. Rinse and repeat for the other three bulbs.

By the way, the towing hookup is done with three wires: turn signal left, turn signal right, and running lights. When you hit the brakes, both turn signal wires are activated in steady (not blinking) mode. The towing cable plug also carries a ground wire that connects to the chassis of each vehicle.

Correction on my last post: the shared wire is of course the running light, not the brake light.

By the way, your car looks terrific! Hope we can meet at the track some day. I do lots of PCA events at Willow Springs, Buttonwillow, California Speedway, etc. - I'm in Orange County.