thomaswatk

I posted this in the electrical section and only got one response that didn't answer my question, so I thought I'd try here. I have a '72 cutlass. When I turn on the low beams both headlights work fine, but when I put the high beam on, neither of the lights on the passenger side come on. In other words the low beam goes out and the high won't come on. The drivers side works fine for high and low beams. I have changed the high beam bulb on the passenger side, and replaced the dimmer switch. Neither had any effect. The thought it might have a bad ground on the passenger side, but since the low beam works ok, I figured it wasn't a ground issue.
Any suggestions will be welcome
Tom

455man

You need a new light bulb for the low beam. It has a high and low filament in it. The low goes off when the highs are hit and the high beam filament comes on. the high beam filament is probably burned out. You could try swapping it with the other side before buying a new one. Might check for power to the high beam bulb.

MDchanic

BUZZZZZZZZ!!!! Wrong answer!

This could be a ground problem. They can be very tricky.

My recommendation would be to troubleshoot this in a systematic way to find the problem.

First, disconnect the headlights on the Driver's Side (the ones that work), then check again. The wires go from the driver's side to the passenger side, so removing the actual driver's bulbs from the circuit will eliminate them as a possible source of trouble.

If there is no change, then the problem is probably not on the driver's side. In that case, start on the passenger side, remove and clean the terminals, one by one (so as not to replace any of them in the wrong slots in the housings), at the same time, check each wire's location with the Chassis Service Manual, to be sure that SOMEONE ELSE didn't screw up the connections. The terminals are removed by shoving a little tool, like a small screwdriver or big paper clip, into the little groove above the terminal, opposite the edge that takes the spade lug, on the side of the plug that plugs into the light. Push in, then pull back on the wire to pull the terminal out of the housing. It make take a bit of fiddling to get it the first few times.
Use a small screwdriver to re-bend the little retainer tab before you put it back together.
Once the terminal is out, I like to use a cordless Dremel mototool with a small wire brush attachment to clean it up, but you can use anything that works.
Also remove the ground wire from the radiator support and clean it and the support.
Snap 'em back together, smear some Vaseline on the contacts to protect them, and see if it works better.

Let us know, and we can give more advice from there.

- Eric

MDchanic

He's got BOTH bulbs not lighting, not just one.
However, you're right - it could be a burned out highbeam bulb, AND a burned out highbeam filament on the low beam bulb at the same time.

I'm dumb enough to have assumed that he had checked for burned out bulbs already. Duh.

- Eric

oldcutlass

You can also swap lamps from the good side to the bad side and see if your symtoms move, and go from there!