Tail light help, please

[1931 flamingo]

1940 ford coupe. I've had stop lights right along, the other day I played with wires in the rear and got tail lights (new rear harness ordered).
Today no tail or stop lights. I have head and park lights so I assume (I know) the CB is OK. There doesn't seem to be any power (test light used) to the rear. What am I missing?? The harness to the rear has not been disturbed except where it terminates in the rear. The prints don't show a fuse.
Any help appreciated and Thanks in advance.
Paul in CT

[4dFord/SC]

Try jumping the brake light switch. If they work, you've identified the problem.

[JSeery]

The tail lights and brake lights should be two totally separate circuits. The brake lights, via the brake light switch should be "hot" all the time, so brake lights whenever the switch is closed. The tail light are powered through the lighting control switch. If both are out I would think it would have to be a connection that includes both or a ground issue at the tail lights themselves.

The stop lights are (at least should be) wired directly from the CB terminal to the stop light switch to the brake lights.

The tail lights would be directly from the CB terminal to the light control switch to the tail lights. The license plate light should also come on with the tail lights. The clock light and instrument lights are also on the same light switch terminal as the tail lights.

[Kube]

Also, the hi/lo beam switch is often the issue with these '40 Fords. Lord knows I've traced this issue to that floor switch many times.
Me? I'd add a temporary ground to each tail lamp bucket so I KNOW grounding isn't an issue.
then, as JSeery has advised, make sure one of the terminals at the brake lamp switch is "hot". If so, jump the two terminals at the brake light switch. If ya get lights then, the switch is poopy.

Tail lamps? Pull your dash light switch out and test for power at the hi/lo switch. If power is there but still no tail lamps, jump from the hot terminal at the hi/lo switch to one of the other terminals. Do the same "jump" to the third terminal. One of those is "HI" and the other "LO". The power needs to flow through that switch.
If none of the above has solved the issue, you'll need to test the head lamp switch itself. Not quite as easy to get under there but may become necessary.

[1931 flamingo]

Bear with me............where is the circuit breaker?? Access to the h/light sw is restricted by the radio.................


Paul in CT Won't be doing more checking til tomorrow a/noon.

[JSeery]

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The CB panel should be under the dash, Kube would know better than me. Earlier models had the CB panels mounted to the firewall inside under the dash. 12250 on the diagram should be the CB and the ignition coil resistor mounted together. It can look like a small square metal box with a lot of cooling holes in it. Something like this one.

[Kube]

Originally Posted by JSeery

The CB panel should be under the dash, Kube would know better than me. Earlier models had the CB panels mounted to the firewall inside under the dash. 12250 on the diagram should be the CB and the ignition coil resistor mounted together. It can look like a small square metal box with a lot of cooling holes in it. Something like this one.

EXACTLY like that! Up high, left side of car, behind dash panel.

[1931 flamingo]

After getting up and down on a creeper about 50 times first with the front end up and then the rear I now have both tail/park and stop lights. I "played" with the dimmer sw off/on several times, stop light sw good and fully depressing brake pedal I have stop lights. I had to run a new wire from about mid way for the tail lights/marker light and tape up a bunch of bare spots in the back. The car is 79 years old and the wiring shows it. Car came with the front harness and the dash harness also. Now the rear and crossover have been ordered. I think I know someone who can/will replace BUT for the time being I'm good to go.


Thanks for the help and quick responses.
Paul in CT

[slowforty]

I also lost my brake lights. Used a test light and had power to the stoplight switch. Drove me nuts, nothing worked,No brake lights. Got a GOOD METER and found out I only had THREE VOLTS going to the stoplight switch. Ran a new wire to the stoplight switch and now the Brake Lights are good. A week later the Brake light switch died and I replaced it, So, On the road again

[TJ]

Originally Posted by 1931 flamingo

After getting up and down on a creeper about 50 times first with the front end up and then the rear I now have both tail/park and stop lights. I "played" with the dimmer sw off/on several times, stop light sw good and fully depressing brake pedal I have stop lights. I had to run a new wire from about mid way for the tail lights/marker light and tape up a bunch of bare spots in the back. The car is 79 years old and the wiring shows it. Car came with the front harness and the dash harness also. Now the rear and crossover have been ordered. I think I know someone who can/will replace BUT for the time being I'm good to go.


Thanks for the help and quick responses.
Paul in CT

If your wiring is that bad I would be disconnecting the battery when the car is parked in the garage until you get the new harness.

[1931 flamingo]

Batt is disconnected in the garage...........................Thanks.
Wiring is serviceable just replacing as a precaution.
Paul

[VeryTangled]

Originally Posted by 1931 flamingo

After getting up and down on a creeper about 50 times...

A lift is your best friend! Doesn't stop the aches but helps.

Recently put new wire harnesses in my '35. Michael Driskell's service was excellent. Old wires very scary!