The Stovebolt Site Forums The Shop Area The Electrical Bay Switching from 4 wire tail lights to 3 wire

I'm running a 1980 wiring harness in my 51 half ton. The wiring calls for separate wires for each tail light function(running, brake, turn plus ground). My light has three wires with the ground. Any ideas? I search the forums but found nothing.

Thanks

if you have 4 wires the turn and brake light are using a seperate bulb 3 wires use the same wire for brake and turn

I realize that but I was hoping someone knew of a way to convert.

What do you have at the front end of the harness? Are you just using the wire or is it connected to a newer steering column? You can buy four to three converters for connecting trailer lights. This would solve your problem if you actually have the separate signals on the harness.

I have a newer steering column and the separate wires. I talked to the people that make the converters for the trailers and they say the converters will not work to convert the taillights because the converters need the load of the vehicle taillights to make the converter work for the trailer.

alpaca11,

I guess I don't understand. A typical light configuration on the rear would be tail, stop and turn. The assembly is grounded either through its housing, or a separate ground to frame.

This leaves tail, stop and turn. TAIL is a single wire from cab to rear. STOP is a single separate wire to left side and to right side.

TURN is achieved through a flasher in the cab and is directed through the same STOP wires.

If the '80 column wiring has more wires, can they be combined or taped off. I put a '76 Nova column in a '51 and don't remember needing anything out of the ordinary.

Am I missing the boat here.

Stuart

I don't agree with the trailer people. The one that I have used taps into the wiring in parallel and there is no load presented to the unit. It has to sense voltage to be able to do it's thing.

They aren't that expensive so I would suggest just trying it out.

I did. It didn't. Wouldn't tying the stop wire to the turn wires cause both lights to go on when a turn signal is used? (I'm going to try that anyway).

If you have an electronic converter, it takes the separate turn and signal wires and provides combined turn and signal wires at the output. It senses when the turn signal is going and cuts out the brake for that side. There would be logic and timers involved. Can you explain what you hooked up and what happened? Also it would be best to try it on four separate bulbs first before hooking up the converter.

ught an electronic converter that (according to the manual) converts a four wire system to a three wire system for a trailer. They all said "for a trailer". Initially I checked the wiring with the old tail lights for the 1980 camaro that I had and it worked fine (separate lamps). With the converter, the turn signals work correctly until I turn on the brake lights. Then the brake lights only work. A heavy duty flasher does not change things.

I guess I would try hooking the Camaro tail lights up at the same time, as if the back end of your truck was the trailer. If it works then I guess that is the only way it will work. I am guessing that you don't have the front lights in the circuit? If so, that would probably do it for you.

If you are using an aftermarket turn signal switch, my suggestion would be to get a new one. Most older turn signal switches aren't made for a use with brake lights, there are many newer ones that are. I believe LMC Truck has one and I have seen one on BlueOvalTruck Parts. Signal Stat has some good units available, but they are pricey, but extremely durable. I think the money you spent on the converter would be wiser spent on a new switch.