The Stovebolt Site Forums The Shop Area The Electrical Bay Brake light problems

When the lights are off both brakelights work.When the lights are on and the brakes are applied the entire left tailight goes out. One of the POs installed a chieftan turn signal unit on the steering column.All of the other lights work fine except for this.

i had same issue it was a pooor ground connection

So I should check the socket for corrosion? I have no idea about elictrical systems fortunatley this is the only electrical problem I have. (for now)

Yes, clean the socket. Then make sure it is grounded to the tail light housing. Be sure the housing is grounded to the bed. Be sure the bed is grounded to the frame. Be sure the frame is grounded to the battery. Any of these connections could be corroded. I always add a ground strap from bed to frame. They were originally grounded by the bed bolts, which have had over 50 years to rust.

Thanks for planning tomorrow for me cletis

Ah Just run a seperate ground wire on that light

Since it works with the lights off, I don't think the ground is the issue. Sounds more like something is hooked up wrong on the hot side. How does it behave with the lights off and the left turn signal set? Same question with the lights on? The left signal should use part of the same circuit as the brake lights, so I would expect it to act strangely as well.

Well now they both come on with the tailights on but not very brightly and now the left brake light does not come on with the lights off Oh well back under there tommorow,at least it's all easy to get to! I know the gound must still be poor for the dim brake lights.

I am having a similar problme with my lights. At times taillights are dim, at times when right flasher on both rear lights try to flash one stronger than other, i noticed this tends to happen when i have headlights on taillights on heater and flasher going weird! any pics so i can check grounds???

mine is a 66 but I will post the pictures,now I have it narrowed down from the plug to the rear wiring harness to the left bake light every thing else is working and I believe the turn signal and brake lights are on the same filament of the bulb right?

Yes, they should be the same filament.

Diagnosing bad grounds is one of the fundamental skills I teach new students when we begin electrical system training. It's absolutely essential knowledge for anyone who wants to be a successful electrical system technician.

The reason the performance is different with the headlights on is the fact that the brake light signal is trying to use the tail light wire as a ground when there's no voltage on it (lights off). Turn the lights on ane the brake signal can no longer find a ground- - - -the brake light goes out alotgether. Check the socket itself for corrosion, and also check the bulbs for a broken filament-to base connection. If the globe can turn in relation to the base a little, the normal ground has broken, and the signal has to back up through the other filament to find a ground. Normally, the filaments ground themselves to the brass base through the little solder joint on the perimeter of the base. Also check the connection of the bulb base to the socket, and the socket's ground connection to the body or bed. The voltage MUST get back to the battery with little or no resistance, so every ground connection from the bulb to the battery must be good. Have fun!
Jerry

YUp same filament. I have dual problems, possibly my brake light switch, a ground on brake light wire, and/or a ground elsewhere that is causing my lights to freak. Will keep posted.

Thanks for taking the time for such a detailed response. The sockets are clean and the bulbs are new I'm going through the wiring for the tailights and cleaning all the connections as I go. One good thing is the tailights are brighter so I am getting something accomplished. I have switched the bulbs around and they both work in the right socket so the left assembly must still have a ground issue. I'm going out in a little while to work on it some more before the game starts.