Packard Forum Index » V-8 (1955-56)

New problem developed today. Headlights and parking lights are apparently kicking the circuit breaker on the headlight switch. In either parking light position or headligh position the headlights( or parking lights) and tailights will come on - then shut off. They will reset and come back on and immediately shut off and repeat the cycle.
The lights worked fine until now.
Considered a short in the circuit that would kick the breaker but doesn't make sense that same thing happens with parking lamps.
First impression was bad headlight switch or circuit breaker but seems to function to turn on lights and circuit breaker is obviously working and resetting.
If anyone has a quick. Long distance trouble shooting tip -'would appreciate any help before tearing things apart.

Parking and tail lights come on together as do head and tail lights. Dash lights also come off tail light terminal which would seem to make the tail light circuit the common link.

From problems others have mentioned I would look carefully in the trunk at both tail light socket areas and make sure something hasn't been placed in the trunk that could have crushed the wire against the end of the socket. Also check the small trough at the rear of the trunk floor where it meets the vertical panel below lid. Wires cross over from left to right at that spot and also exit to license lamps. Make sure something hasn't fallen in and damaged the loom and also look at the grommet and hole where wires exit to the license lamps. Also the condition of wire under the bumper going to license lamps.

If the trunk area checks good then the dash lights would need checking. The way the sockets are constructed the wire enters a small hole in the center of the shell. If the wire insulation has cracked or shrunk back there is potential for the wire to touch against that hole and short to the grounded shell. All the bulbs are in parallel so any one of them (believe yours is a V8 so 4 on instruments, 1 on each air control) could be a problem. The ign key lamp and gear shift indicator lamp are also in the group. The dash light rheostat area at dash end of headlight switch and its wire connection to tail light terminal on switch for their power is another potential source of problems.

HH- Thanks for the quick reply. I recently pulled the tank to change the fuel sending unit and problem developed after that. Good place to start looking for a short. At least I fit better under the car than under the dash. I'll post my results. Thanks again for your help.
RJR

HH - Well I guess it was too much to hope that anything with the Caribbean would be simple. The wires at the tailights, trunk and license plate lights look fine.
I crawled under the dash and pulled the headlight switch and replaced it with one I had from the parts car- the short still exists and kicks the breaker.
There are essentially five plugs into the headlight switch. On the inside of the switch there is a pink/ green double at the rear near the circuit breaker; a brown single wire plug and a gray wire plug on the same side. There is a small black wire that plugs into a socket on the top right side of the switch and heavy double black wire that plugs to the outside of the front of the switch with the thinner wire plugging back into the switch on the outside of the switch near the center of the left side.
As a beginning diagnostic, would pulling each of the plugs individually and activating the parking and headlights allow narrowing down the area where the short is occurring.
Tracing the wires from the switch seems fairly routine.
Sort of hoping it is not a shorted wire in the dash lights-- hanging upside down over the seat was no fun at all.
Didn't mind the position so much 50 years ago.LOL
Thanks
RJR

I would suspect any and all headlight, parking/ fr directional, side lamp lights with cloth covered wires down stream of the vehicle wire harness plugs. If a 1955 like mine there were compromised wire insulation in these areas. All should be eliminated - repl with new.

You can pull the wires one at a time and that may help isolate the problem. The terminal near the circuit breaker is the park lights and ign switch light, the one in the middle is tail, license, running and dash lights etc and the end one toward the knob is headlights.

The short black jumper from the middle terminal to the end terminal on the ceramic rheostat is the feed for the dash lights. That might be the one to pull first as it will eliminate almost everything under the dash. Next to go would be the other black wire on the middle terminal. It is the feed for the tail, license and running lights.

Speaking of running lights, those are worth looking into. I don't know if the top mechanism comes anywhere close to them but the quarter windows do. Possibly a wire has strayed and come too close to a moving item.

The final two would be the pink parking light or green ign key on the front terminal.

Only thing left is gray headlight wire and since it fails in parking light position those are not even on. The other wires coming off the ceramic portion are part of a different circuit which do not go thru the breaker. They shouldn't be involved unless one is touching somewhere it shouldn't.

All 55/56 Packards and Clippers had plastic insulated wiring, except for possibly heater blower. Most common reason for circuit breaker cycling is a defective breaker.

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Agreed. Old CBs are a known issue but the plastic insulation can become brittle and crack and can also shrink back slightly at the lamp sockets exposing the center conductor to the shell so is also a known issue.

Since it was mentioned the headlight switch was swapped with another and no improvement, I am assuming that also means the circuit breaker was not transferred from one switch to the other. If it was, that is absolutely a place to check although typically the weak breakers cycle when headlights are on and pulling heavy current but are usually OK with only the parking and tail lights on.

Even if not the problem today, 20 amp stud mount breakers are inexpensive and readily available at Napa etc. Because they are so old, to eliminate any possibility and to become proactive for future failures it wouldn't hurt to change it.

Also traditional rubber/cloth wiring on 55/56 from the inner fender forward junction block to the headlamps/parking lamps.

Cloth wires from j bloch to headlights, to lic plate light, to trunk light and fr markers if i remember correctly. Though not relevent to this thread, also to both heater blower fans, spartan horns and washer jar . As i said, all should be replaced. Btw, is the trunk light powered from the park lamp ckt?