Hi-Beam is Out

[KyleSeal]

Recently I noticed my high beam passenger headlight is out on my 1970 c10.

I replaced the bulb and the same problem - then I cleaned the ground and put dielectric on it, nothing still.

Any ideas?

[dwcsr]

clean ground doesn't mean good ground. Get you test meter out and check it

[VetteVet]

Check the green wire on the plug in terminal. It's probably corroded. The power for the right headlight is jumpered from the left so the green wire might be cut coming from the left headlight. To check that, turn on the lights to high beams and pull the plug on the right light harness and check the green wire for 12 volts with a voltmeter.

[KyleSeal]

Originally Posted by VetteVet

Check the green wire on the plug in terminal. It's probably corroded. The power for the right headlight is jumpered from the left so the green wire might be cut coming from the left headlight. To check that, turn on the lights to high beams and pull the plug on the right light harness and check the green wire for 12 volts with a voltmeter.

Do you have a thread I could refer to? My wiring is so messed up, I'm getting a new harness but not until after painting is done, there's literally 3 crimps and 3 colors for on wire.

[VetteVet]

Here is a diagram showing the wiring. The tan and green wires come through the firewall block from the dimmer switch and run to the left headlight plug. They join the wires to the right headlight plug there and run over to the right headlight.

When you turn on the headlight switch you should get power to the dimmer switch via a 12 gauge blue wire, and it switches power to the tan or green wire. Green is high beam and tan is low beam. You must have power to the left headlight so your problem is between the left headlight and the right headlight.
You can see in the diagram that the tan and green wire run from the left light over to the right. The tan wire is the low beam wire and it must be OK because you say the high beam doesn't work. That means the ground is good and either the high beam filament is burned out or the green wire or the plug is bad.

If you don't have the correct wiring then you will have to trace it through the harness.

Check the diagram.

[KyleSeal]

Originally Posted by VetteVet

Here is a diagram showing the wiring. The tan and green wires come through the firewall block from the dimmer switch and run to the left headlight plug. They join the wires to the right headlight plug there and run over to the right headlight.

When you turn on the headlight switch you should get power to the dimmer switch via a 12 gauge blue wire, and it switches power to the tan or green wire. Green is high beam and tan is low beam. You must have power to the left headlight so your problem is between the left headlight and the right headlight.
You can see in the diagram that the tan and green wire run from the left light over to the right. The tan wire is the low beam wire and it must be OK because you say the high beam doesn't work. That means the ground is good and either the high beam filament is burned out or the green wire or the plug is bad.

If you don't have the correct wiring then you will have to trace it through the harness.

Check the diagram.

If we were to attach a relay kit do you think that the problem may be fixed?

[VetteVet]

Well if you have both beams on the drivers side then your power wires from the headlight switch are good. If the low beam works on the right side then the ground is good and the tan wire for low beam on the passenger side is OK. The only thing left is the green wire for the right side high beam is bad or the high beam element is bad. I would run a hot wire from the battery positive to the green wire on the right headlight plug and see if the light comes on. If it does and the left high beam does not then the green wire in the harness is bad of one of the light connections is bad.

If you get a relay kit that has new wires and plugs in it then it will fix the problem.

[KyleSeal]

After a long time of searching and a long winter of work on the truck I found the problem. Passenger side hi beam is out due to drive side hi beam wire being a little worn and needed a little dielectic and wiggling into place. Thanks for all the help.