No brake lights 40 coupe deluxe

[Fordyguy]

I noticed recently that my brake lights had stopped working so I thought I’ll just put a new switch on. Well, that didn’t work. I pulled out wiring diagram, checked all the wires, grounds. I even replace bulbs. So far all the wires look like they’re hooked up correctly. After doing a few checks, now when you press the brakes, my tail lights and my license plate light comes on. When you pull out the headlight switch, I do not have tail lights or license plate. I did place a jumper wire between the two wires and all the lights on the back light up including the license plate light. The alligator clips do get warm. i’m stuck scratching my head. Any ideas. Thanks!

[Kurt in NJ]

Single contact bulb in a double contact socket?
Bulb base ground

[Fordyguy]

They are double contacts and so are the sockets. I failed to mention that I do not have any turn signals on the car in case anyone asks.

[Kube]

Originally Posted by Fordyguy

I noticed recently that my brake lights had stopped working so I thought I’ll just put a new switch on. Well, that didn’t work. I pulled out wiring diagram, checked all the wires, grounds. I even replace bulbs. So far all the wires look like they’re hooked up correctly. After doing a few checks, now when you press the brakes, my tail lights and my license plate light comes on. When you pull out the headlight switch, I do not have tail lights or license plate. I did place a jumper wire between the two wires and all the lights on the back light up including the license plate light. The alligator clips do get warm. i’m stuck scratching my head. Any ideas. Thanks!

I think you need to check the wiring routing once again. Very carefully...
And as s die note of sorts, the repop switches are more often bad right out of the package then they are good.

[Newc]

If a pressure switch, some folks use the Harley Davidson [lower pressure] switch. Newc

[Terry,OH]

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You replaces what jumper between the two wires? Where did you do this?

[Steelie Dave]

After trying a known good switch and a new stop light switch that did not work after a brake system rehab I turned to a low pressure switch. I found an exact match to the original post type. Try a TMaster low pressure brake light switch that costs about $13.

[TJ]

As Kube mentioned go back over your wiring again. I would also recommend that make sure the tail lamp housings have a good ground. How old is your wiring? If it's old and you see evidence of bad insulation it may be time to replace it.

[slowforty]

Check the voltage going to the stoplight switch. Use a good meter. On my 40 the test light lit but no lights. Using a Good meter found I only had 3 volts to the switch. Enough to light a test light but did not know the voltage. 3 volts lights the tester but did not tell me how much voltage that was going to the stop light switch.

[Fordyguy]

Wiring isn’t that old. I even took them off and checked. I’ll go back over the wiring tomorrow.just don’t understand why tail lights and license plate lights up when pressing brake now and no tail lights when you turn on light. I haven’t rewired anything.

[Fordyguy]

Originally Posted by Terry,OH

You replaces what jumper between the two wires? Where did you do this?

Jumper wire to the 2 wires leaving the stop light switch

[Bob C]

Bad grounds can do strange things.

[paul2748]

If they were working before than it's not your wiring. As someone ,mentioned, check grounding. Rust or oxidation may be on one of the housings. Try a temporary ground on one light at a time and see it that fixes your problem. Sounds like it's grounds.

[drolston]

One of your tail light housings or lamp holders may have lost its ground to the chassis. When the brake switch sends voltage to the filament of that brake light bulb, instead of going to chassis ground and lighting the bulb, it goes to the housing ground only. The housing ground is also connected as ground to the tail light bulb in the same housing. The voltage then goes backwards through ground side of that tail light bulb to the input side of that tail light bulb. The input side of that bulb is also connected to the input of the other tail light and license plate bulb. Those bulbs are connected to a proper ground and so they turn on. Probably dimmer than normal because the current is flowing through two filaments instead of one.



Bad grounds do indeed cause strange things!

[Fordyguy]

Ok guys I went back out ad took a look this morning. I checked the contacts and it was turned a little causing it not to come on. However I still have something wrong. When I press the brakes my taillight, license plate and dash lights come on. Took out bulbs at tested leads and both hot with lights on or brakes on. I have not crossed any wires all colors match. I have ran new ground wires from tail light housing to the frame. Seems like something is crossed but I have not switched anything. Could light switch have anything to do with it?

[TJ]

Put ground wires on one mounting stud of each tail lamp and run them to the frame and see if that helps. Make sure the wires are going to clean metal surfaces.

[Fordyguy]

Originally Posted by TJ

Put ground wires on one mounting stud of each tail lamp and run them to the frame and see if that helps. Make sure the wires are going to clean metal surfaces.

I ran new ground wires and getting good connections. Both leads are still hot when lights are on. Pressing the brake lights my tail lights, license plate, and dash lights come on. I’m so confused lol!

[drolston]

Originally Posted by Fordyguy

I ran new ground wires and getting good connections. Both leads are still hot when lights are on. Pressing the brake lights my tail lights, license plate, and dash lights come on. I’m so confused lol!

Exactly where did you connect the ground wires? If it was not from the actual lamp socket to chassis ground, you may still have the problem I described. And furthermore, if the connection between the socket and the brass base of the bulb is not clean, you could get the problem. Are any of the bulb sockets corroded; like rusty or white powder coated?
If you have an Ohm meter, check ground from the socket-engaging tab/pin on the installed bulb to chassis ground, like the bumper. Anything more than one Ohm and you have a problem. Check all bulbs in both tail light housings.