Club Cobra - Taillight gremlins

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Taillight gremlins

A friend recently told me that my brake lights were not working. So I started with the obvious and changed the bulbs. No effect. So I took the taillights out and started trying to figure out why the lights would not go on. There are two wires coming into each taillight. One is for the headlights and the other is for brake lights and turn signal. When I test each wire each one of them has power. When I attach the headlight wire to the lamp socket the light goes on. When I attach the brake wire to the socket the brake light will not go on. Thinking maybe it was a bulb problem I attached the headlight wire to the opposite clip and the brake light went on. Therefore the bulb is not the problem. Then I thought maybe I had a ground problem. So I attached a wire to the frame and into the taillight assembly. Same thing the taillight will go on but not the brake light. When I take the bulb out of the assembly and looked down into the socket I put my voltmeter to the small bump where the bulb connects and it has power. The puzzling thing to me is why when I put the bulb back in no power goes to the brake light filament. The bulb is orientated correctly with the short and long side in the correct grooves. Does anybody have any ideas on what to try next. Thanks

Do you have the two round tail lights on each side or the single rectangular one?

Ron

HMMMMMM! check the tail light sockets..maybe one of them is grounding out the stop light wire feed when it's hot. Loose connection..touching the side of the bulb socket?

Get another stop light set up to use as a test device, that will eliminate the tail lights as a potential problem. Also check the stop light switch for it's connection and proper funtion...process of elimination.

Good luck, Bill

I have the rectangular lights

On SPF there are a couple of fuses just for parking lights. Is the blinker on the side that is not working for brakes work?

I think you’ll find that the running lights and the brake lights are on the same bulb and the turn signal is its own bulb. What you need to do is check first if you have running lights on both sides. Then check if you have brake lights. These should be on the same bulb – a duel filament. You should have a ground on each lamp holder too. If no brake lights, check the brake light switch – which is probably located on the brake peddle. Use a volt meter to see if you are indeed have power at the pedal and then check if you are sending power to the rear of the car…do this for the running lights too. If there is power on all 4 wires at the bulb holder and still no lights – you have a ground problem at the lamp assembly for the bulb. Once you have that working address the turn signal issue. Confirm power to the back of the car, if it’s live at the bulb holder, once again it’s a ground problem at the bulb holder. If no power at the turn signal bulb holder, check for power at the flasher unit. Of course, I assume you have checked all your fuses first…Wish I had a wiring diagram for a Kirkham to use for reference when things like this come up on CC.

Check and make sure the bumps on the bulbs are aligned with nubs in the socket. I had a socket one time that had nubs that would not contact the bumps on the bulb correctly when the bulb was installed.
Jay

It's likely that you are using some kind of relay (we use a trailer adapter) that merges the signal and brake light outputs to the single filament. It's also possible that the relay shows a voltage with no load but will not have enough current to light a filament.

So...

Remove the bulb from the socket, ground the outside and connect the brake light wire directly to either of the bulb's bottom contacts.

Does the bulb light on both the contacts? If so, there's probably a problem with the socket. If the bulb doesn't light, your relay may be bad or you lack good continuity in the entire brake switch-to-light circuit.