Strange electrical problem (question)

[brimcc]

My 1969 was converted at some point in its life to a slantnose with pop up headlights. I have had the motors rebuilt a few times over the years, now this problem. The drivers light will continue to pop up and down after the ignition is turned off. Turn the headlights on and it will stay up, turn the lights off and it continues to go up and down. To stop the problem I have disconnected the negative side of the battery. After connecting a volt metre to the disconnect negative cable and positive side of battery I am getting a small amount of voltage, about one volt. I figure I must have a short somewhere.

Any ideas would be appreciated.

Thanks.

[Joe Bob]

You're getting a cross over bleed form an adjacent 12v source. A meter and judicious pulling of fuses will reveal the culprit.

[steely]

This is just a guess, and I agree with JB, but I am thinking that the issue is similar to the occasional one you might see with the reed switches on the windshield wipers that can act up.

The parking voltage is getting to the drive circuit (which you expect to be dead), but I am not familiar with the beasts.
Do you know if you have a relay in your headlight circuit?
Since it is just one, can you see if there is a position/limit switch associated with the light itself?
Watch your fingers if you're poking around in there - and not just because of the voltage. :-)

[brimcc]

Pulled fuses which are not marked well. Once I pull the brake fuse the metre goes to zero. Put fuse back in then touch the negative to battery then remove cable goes back up on the metre. With the negative cable disconnected (with metre still) the voltage drops down to just above zero over 5-10 minutes. If it was a dead short should the voltage not stay the same?

[steely]

Originally Posted by brimcc

Pulled fuses which are not marked well. Once I pull the brake fuse the metre goes to zero. Put fuse back in then touch the negative to battery then remove cable goes back up on the metre. With the negative cable disconnected (with metre still) the voltage drops down to just above zero over 5-10 minutes. If it was a dead short should the voltage not stay the same?

I don't have a good answer for your question here, I am not familiar with this troubleshooting technique.

I would recommend/ask you to post a picture of the lamp motor assembly.
Better yet, a picture of the power connector that goes with it.
Then, with the connector disconnected - take voltage readings to ground for each pin with everything off, then with the key in/on, and then with the headlights turned on (so the motor is being driven).

Then try the working side and repeat the measurements.

If the measurements are different, it could be your headlight switch.
If the measurements are the same, I'm guessing it could be the motor assembly.

How does this sound?

[brimcc]

Guess it's not the brake fuse, it's the gauge fuse. Just replace oil pressure switch last week and has worked fine since then. Now I notice gauge is off chart. I will check the headlight motors as you suggested after I put the brake lights back together.