For my pulling truck I have most all of the wiring harness striped out of the truck. I need to hookup a light that will turn on while I am in reverse. Does anyone know what the easiest and cheepest way to do this is? I already have the light. If you would like to know what wiring I do have you can check my VIN Question post and look for the wiring diagram that I posted.

Thank you.

 

I would use the Backup lamp circut for your light.

Do you have an automatic or a a standard transmission? You could possibly use the Backup lamp switch (standard tranny) or the neutral safety switch (Automatic).

It seems you may have removed the circut from your truck so you could wire it like this...

1: From a 12 volt power source (The Starter Solenoid's battery terminal is a good place), connect a wire with a inline fuse, to the backup lamp switch, or neutral safety switch white/purple wire connection.

2: Then from the back-up switch, or neutral switch, hook another wire to the Black/red wire connection, and hook that to the apropriate terminal on the power relay you buy.

3: Hook another 12v power source of heavier wire, with another fuse (From the starter solenoid), to the 12v power source, on the Relay. Then hook up another wire to the device side of the relay, and hook it up to your light. Simular to the tech article on hooking up a relay for your headlamps, but instead of using the headlamp switch, you use the backup lamp switch, as the relay switch.


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If however if your truck is wired for taillights or backup lights already, you can splice in on the back-up lamp circuts, black/red wire, for the light. But I would still use some type of power relay with heavier wire, depending on the candlepower of the light you tend to use.

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In a pinch you could just use a toggle switch on the dash to turn the light on and off, but you would have to literally turn it on and off yourself. possibly the easiest of the 3 possibilities however.

 

What year truck ?

you didn't mention it

The circuitry changed in 78

If the light is a strong one I would use the NSS to fire up a relay for the more intense light.
The original BU light wiring is 18 gauge and hardly powerful enough to power a large light.

 

Sorry guys. The truck is a 79 F250 2wd but the motor and trans is out of an 84 ambulance (460/C6). If you want to see what wiring I currently have you can look at this sketch as it is what we used to wire the truck. This is just a single light that needs to come on to show the sled operators that the truck is in reverse so that nobody gets crushed between the truck and the sled.

 

Well, if it doesn't have to be very bright,


Then what I would do is hook from the starter solenoid, run a 12v inline-fused wire to the neutral safety switch located on the transmission (I believe). You may need to buy a NSS for a 1984 C-6 if the switch isn't on the truck anymore. Then run the output wire that would have went to the backup lamps to your light.

 

First let me say please forgive my ignorance. I think there is a small box on the side of the trans with 4 or 5 wires coming out of it. Is that the NSS? Any body know what color of wires would be the incoming power and the backup lights?

 

According to the 1979 wiring diagram, the colors are..

white/purple 12v input
black/red output for the lights


According to my 1984 wiring diagram, it is...

Purple/orange is the 12v input
black/pink is the output for the backup lights.

the other wires are to keep the truck from starting in gear. Red/Light Blue

Hope this helps,

 

Thank you. I will let you know how it works.

 

That worked like a champ. THANKS!

 

Yes zombie thread, but I need to subscribe for later on.