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.
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

Dan

I haven't done it, but I've thought about it. The first thing is to figure out what wires will be coming from the tow vehicle. If it is the standard old 4 wire connection, then it will be difficult because the running lights and blinkers are shared (but they of course are not shared on the 914). So the only way I would do this is if you have a 5 wire connection (ground, brake, left blinker, right blinker, and running lights).

You'll need to connect the ground to the body of the 914. Then you should be able to easily splice into the running lights and the right blinker at the right front corner of the car. Left blinker at the left front corner. Then you only need to run a single wire into the passenger compartment where you should be able to tap into the brake lights at the brake switch in the pedal cluster. That should do it.

Demick

QUOTE

No I am not interested in aftermarket magnetic tow lights.

Hmmm
I like 'em. I put a paper plate between them and my paint.
Right on the engine lid.

KT

Demick,
That is pretty much what I was thinking. I have been trying to figure out the separate brake turns vs. the combined coming from the tow vehicle. I was thinking that the running brake lights on the 914 have a two filament bulb. If I can tap into that circuit I could use the brake light, running light also as the turn signal....I will have to look at it more closely and get out my test light and my digital electrical tester.

My tow vehicle is a 2000 Suburban...it has separate turn, running and brake lights just like the 914. Unforturnately the tow package 7 pin connector has the lights for turn and brake on the same circuit, just like older american cars and trucks. It is that way since almost all RVs and boat trailers have the combined turn and brake lights. I need to see if I can tap directly into the circuit of the 'burb, before the wiring harness for the RV plug.
I have seen it done....on someone elses 914 years ago. But he no longer has the car and he didn't do the wiring. They flat towed with an old Chevy S10 Blazer.

Greg Braun....the old white 914 that you and John used to share before you bought the blue car, was wired...did you guys do it or have it done?

QUOTE (trekkor @ Mar 16 2006, 09:43 PM)

QUOTE No I am not interested in aftermarket magnetic tow lights. Hmmm I like 'em. I put a paper plate between them and my paint. Right on the engine lid. KT

Trekkor,
I have nothing against the lights in and of themselves. I just want to find a cleaner, simpler solution, for me. IMO

I also don't like the idea of wires running along the outside of the car to the lights.

I want everything other than the short pigtail for the tow vehicle to be contained in the 914. that way there is nothing to remove...just disconnect the plug and ready to go...

Dan, I did this about 5 years ago and have been flat towing it ever since. Works great.

I just tapped off of the wires leading to the brake lights and rear turn signals...

*** BUT ***

I had to use diodes between the towing wires and the car wiring. This prevents the voltage from the tow vehicle feeding back into the 914. When I tried it without the diodes, I got lots of weird effects and I'm sure it was not good for the car's electrics, particularly the gauges.

I got the diodes from my local Camping World. They are sealed units with spade connectors, easy to mount and wire up. I used four, one for each turn signal light and one for each brake light. Three would probably work, but I chose to split the brake light wire before the diodes rather than after.

Racergreg, thanks for the info.
could you give me any specific information, like where did you tap into the 914 for the various circuits? Brakes, turn, running?

And are the diodes you are referring to specifically for this type of application...4 down flat towed vehicles behind motorhomes?
About what was the cost for the diodes?

Also, you ran one line for each.
1 left turn
1 right turn
1 brake (2 in your application)
1 running

What about a ground from tow vehicle to 914?

The electical feedback issue of the tow vehicle into the 914 was one I was concerned about so this helps answer at least a few of my questions.

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.

Thanks again for the info. I will check out my local Camping World.

Got it all done. Thanks for the tips and the info racergreg.
Pretty much like you said. Went down to Campingworld in San Martin today and picked up my supplies. 4 diodes and 30' of 4 wire loom. GYBW.
Took about an hour to run wires to front left of front trunk and back to rear left of rear trunk
Installed diodes one for each running lights feed from car, brake/turn.
Doing it this way eliminates the amber/red normal signal markers when car is being towed, everything works as normal when driving car solo.
What it does is uses the running lights as normal, then uses the running/brake light on the 914 to do the brake and turn duties like most trailers are wired.
Now the brake/running is now the brake/ turn and running.
Everything is sef contained now. No magnetic lights or extraneous wires running along the outside of the car while towing.
This along with my tow bracket I got from David Lee and my flat towing is clean and simple. Only need to disconnect two pins for the tow bar, two saftey chains and one simple 4 prong plug for the lights.
2 minutes to hook up or unhook.