I have a brake light on the rear drivers side but it only works when the headlights are on. Whats wrong here ?
Randy Glowacki, Parsippany, NJ
Does the tail light work? You must have a problem with the wiring. The brake light is wired from battery through brake light switch to the brake light. The tail light is wired from the battery through the headlight switch to the tail light. Both lights use the same ground connection at the rear of the car. Question, do you have two separate lights or one bulb with both brake light and tail light? Here is what I think might be the cause of the problem. There is a contact on the block on the firewall which goes through the light switch. It is for the tail light. I think you might have the brake light wire to the brake light switch connected to that contact. If your wires are colored right, the yellow wire goes from the battery to the connecting block. That is where you should have the wire to the brake light connected. If your car has a starter, you could also connect that wire to the starter switch on the same connection which goes to the battery.
Sounds like the power for the brake light is coming from the tail light circuit. Most T's did not have a brake light circuit so who ever installed the brake light probably tapped into the tail light circuit at some point.
The car has two tail lights. Only the one on the drivers side also acts as a brake light.
The problem with a Model T is that when the ignition switch is on the normal MAG driving position there is no switched accessory power.
You have a choice of powering your brake light a few ways.
1. It can be connected to the tail light circuit like yours. Not recommended because the lights have to be on all the time.
2. You can add a separate accessory switch power the stop light and any other accessories.
3. You can connect the brake light to an always on circuit like at the starter switch. That is the way mine is and it works fine unless the brake pedal and/or brake light stays on for any reason when not driving the car.