Tail/Stop Lamp question

[Kurt B.]

On my 68 when I turn on the lights all 4 taillights light up as normal, however, when I step on the brake pedal 3 of the lights get brighter (as they should) and the driver side outboard taillamp goes dead. Release the brake and bulb lights up as normal.
I tried switching bulbs with the adjacent lamp and the same problem remains with the driver side outboard lamp. The problem remains the same and does not move to another lamp. I am assuming it is not ground related as the lamps light up correctly until the brake pedal is depressed. I am also assuming it is not bulb related since I switched bulbs.
The lamp housings and harness were removed and reinstalled by the body shop when the car was painted last week.
I am not very electrical savvy and would appreciate any help or suggestions as I am in proces of trying to reassemble the car.
Also, are # 1157 the correct bulbs?
Thank you in advance,
Kurt # 26406

[Michael H.]

Re: Tail/Stop Lamp question

Kurt,

Your problen is a poor ground on the lamp that goes out when the brake is applied. Very common problem. The lamps are all grounded separately on the mounting stud and it probably needs to be cleaned and/or tightened.

[Timothy B.]

Re: Tail/Stop Lamp question

Kurt,

The 1157 is the correct tail/stop bulb. I would remove the bulb from the socket, get a test light and ground it to the frame and turn on the tail lights and left blinker then check to see if there is power on both contacts inside that socket. If your test light shows power on both contacts then I bet there is a ground problem with that tail light housing. I believe each light housing has it's own ground and they are attached to the speed nuts holding the assembly in place, it may just be dirty.

[Kurt B.]

Re: Tail/Stop Lamp question

Thank you for the responses. I am confused however: If it is a ground problem with the lamp socket, why does it work perfect UNTIL the brake is depressed. I would think a faulty ground would prevent the lamp from lighting at all. The taillight works perfect until I activate the brake light and then the entire fixture goes dark, only to light up again once the brake is released. My wife insists on dinner so in the interest of marital harmony I will need to delay removing and cleaning the grounds until later this evening or early morning. Thanks again for the much needed help.
Kurt

[Paul L.]

Re: Tail/Stop Lamp question

You mave have the bulb in 180 degrees out. It can be done! Check the #1157 offset pins carefully wrt the socket grooves for the pins.

[Timothy B.]

Re: Tail/Stop Lamp question

Kurt,

The ground may be dirty thus allowing some current to complete it's circuit and lite the tail lamp but when both sides of the lamp are lit the current flowing can not complete because of a bad (dirty) ground and thus the bulb goes dim or out. A quick check is to use a test light and ground it to the frame and remove the bulb and check both contacts inside the socket.

[Michael H.]

Philement

Kurt,

Enjoy your dinner and worry not about the tail light problem. As Timothy stated, there's just enough of a ground to operate the low amp filement....filiment...file.. the little wire do dad inside the bulb, but when the brake or t-signal is operated, the ground requirements exceed that of which you now have on that particular lamp.

Fillement....fillim.....Philement.....

[Jim T.]

Re: Tail/Stop Lamp question

The problem may very well be with the installer of wiring at the body shop. My 68 is up on my lift so it was easy to do a quick inspection of the ground wires. Both tail lights on the drivers side have one ground wire connecting the bottom terminal on the tail light. The outboard light also has a ground wire running from the frame above the muffler. This ground wire is connected to the same terminal that is attached to the light, cannot seperate these wires from the terminal end. The other tail light also has a wire from its terminal end that goes up into the wiring harness. It cannot be separated from the terminal end. Good luck.

[Wayne W.]

Re: Philement

Actually what it does is, it grounds back through the brake light circuit. When you then apply power to that circuit, the back feed is broken and it has no place to ground. So the light goes out because it has 12V on both terminals.

[Kurt B.]

You gentlemen were correct

You guys are great.
I removed and cleaned the ground on the defective tail lamp housing and all lamps now work perfectly including the brake light function. Thank you for your collective help, I sincerely appreciate it.
Kurt