Packard Forum Index » Pre-War (1899-1942)

Well, after two years of starts and stops and other projects getting in the way, the 39 120 rewiring is completed. I used a kit from Potomac Packards, which was well done with good directions. The problem was getting the time to put it all together.

The fun part was changing the 12 volt alternator system back to a 6 volt generator. The generator was a good used one I had on the parts shelf, but it wouldn't product electricity when the engine was fired up. Turns out that I had painted the firewall before I put the accessories back on, and forgot to sand it away under the screws for the voltage regulator, so no ground. A few minutes with a screwdriver and some sand paper cured that problem.

However, a more troubling problem is the lights (sealed beam type). When I pull the light switch on, the ammeter jumps back and forth, and you can hear the circuit breaker opening and closing. And the lights don't work. The turn indicators work fine. I looked at the light switch (the one with about a dozen wires on it) and none of the wires appear to be touching another one. Any suggestions as to where to look for problems?

Regardless, it was nice to hear the old 282 merrily idling away after two years of hibernation. I should be able to take it out for a drive this weekend, as long as I don't drive it at night!

There have been some who have had issues with shorted dimmer switches so always a possibility. If the leads to the headlight buckets somehow got crossed, another possibility.

Echlin/NAPA still offers OEM-style dimmer switches for many makes and models and I agree with HH, a shorted dimmer switch fits the symptoms.

thanks guys - I will try changing the leads to the lights, and if that doesn't work, the dimmer switch is next.

David; Also check the ground on the head lights.

Found two wires in the headlight that was crossed (wrong wire to high and low ) corrected that. Swapped out the dimmer switch for a new Napa Echlin DS101 (just added to the X Ref) and still no good. The taillights and headlights are still not working. I guess I'll start sorting thru the wiring again to see if I left something unattached. The ammeter still jumps around when I pull the light switch on.

That jumping certainly indicates a short and the circuit breaker operating. Just out of curiosity does the new loom instructions show both switch versions or agree with the illustrations in the 38-9 service manual on the dual bulb feeds from the headlight switch. Do the seal beams just replace the regular bulbs wire for wire and functions remain the same?

I would start by disconnecting the rear light harness, the front harness and the dimmer wires. Check to see if your circuit breaker still keeps breaking. If all is OK then connect the rear harness and check again, and so on in order to isolate the trouble area. The tried and true "divide and conquer"

You could also have a short in the light switch. If the switch is out of the car this can be readily checked by looking for a ground fault. If it is in the car, you can disconnect the draw wires (to the lights), and operate the switch and see if you get a draw on the ammeter. You should not.

We had a short in the light switch on our 38. I still don't know what caused it, but I took the switch apart, cleaned it up (it was filthy), and the short went away.

Cheers,

Tom

All good suggestions guys. I'll try them all over the next few days and see if we can find a smoking (hopefully a metaphor) gun.