48 Plymouth fender lights/headlight operation

[41P11Coupe]

I'm verifying/repairing the wiring on my 48 Plymouth. All the wires were there going to the appropriate places but the insulation was gone about  1 1/2" from the ends. Of course over the years things get changed, spliced, taped, moved, broken etc.. 

I've never operated the electrical system of a car this year. I'm working on the front lower fender and headlights. When I pull the light switch out to the first detent the fender lights go on, pull the knob all the way out for the headlights and the lower fender lights go off. My headlights don't go on because I need new lights. I don't know if the fender lights are dependent on them when I pull the knob out all the way.Is this correct I don't know. I keep wanting to compare it to a newer system but I know I cant.

 

[Don Coatney]

This might or might not help.

[Dan Hiebert]

That switch/light operation is correct.  "Parking" lights are on at first switch detent, that's front and rear.  Headlights come on, parking lights go out (front only) with switch all the way out.

[greg g]

Your high beam selector switch can cause a problem.  It is basically a rotary switch that alternates the output terminal with each operation.  Corrosion can build on the internal contacts preventing either or both outputs to not work or work but putting a lot of resistance in the circuit.  The switch can many times be cleared by a dozen or so stomps.  The other area to check is the terminal block on the radiator support.  Corrosion there can also introduce unwanted resistance into the circuits. While you are addressing wires make sure your headlamp ground wires go to a good solid corrosion free connection to the body.  Adding a ground strap from the fire wall to the engine or frame can also contribute to proper operation of body mounted electrical components.  Front parking / running lamps went off with headlamps on till 1962/63, your car is switched that way.  Make sure you are replacing wire with proper gauge needed for 6 volt operation, I would recommend 12 gauge for head lamps and 14 gauge for parking/signal lamps.  16 and 18 gauge used for modern 12 volt systems have very limited use on 6 volt circuits.  You also might want to consider repowering you brake light switch.  Easy to make up a fused lead directly from the battery side of the starter solenoid directly to the switch by passing passing it through the headlamp switch.  Just remove the stock power line from the switch tape it off and zip tie it to abandon it in place.  And last but not least, assure your primary battery cables are not thin modern 12 volt ones.  You need 1 gauge minimum.

[41P11Coupe]

OK

So I got new headlights put them in and when I pull out the switch they do not come on. I verified the ground, the wires going to the headlight, the terminal block and they check out ok. I'm looking at the schematic and there are two wires going to the front headlights. They come from the headlight beam switch. So I pull out my meter and I have continuity to ground from one of these two wires that terminate at the terminal block. I must have a short some where between these two. Tomorrow I will trace these two wires back to the headlight beam switch and go from there.

[desoto1939]

Are you sure that you have power to the low side and the high side of the plastic plug for the lights. But a test light on the low beam connector on the plastic connector and see if you test light indicates a complete connection. Do the same with the high beams. Also test the same at the junction block for high and low beam.  Might also be that you have two bard headlights.

When you depress the floor high/low beam switch do you have power to  the light junction box for the high and low depending on how the floor switch is pressed?  If you have high and low power continuity then the issue would be from the junction block and the individual wire that is leading to the plastic socket for the light bulb.  Also check that the contacts are clean and secure and the wires are tight also check the ground wire in the plastic socket you might have lost the ground connection.

 

Rich Hartung 

[greg g]

Do you have power t the beam selector switch?  Do you have power through the switch to the out put of the switch?  Do you have power to the terminal block?  Have you checked the fuse which is contained on the headlamp switch assembly?

[41P11Coupe]

There was a short in the brake light / pillar circuit. I removed that circuit from the light switch and I had power. Upon looking at the brake light wires I discovered one was disconnected and touching the frame. I'm hoping that was it and not the pillar circuit as that one goes under the liner,  There is a circuit breaker built into the switch, it is not encased in a housing- I can see the contact points and the metal disc and they look fine.  I will be doing the rear lights next and will address the brake light / pillar circuit when I move to that.

Thank you everyone for your input,  very much help.