Need some input on electrical problem
 

Doing some updates on my brothers 49 F1 that he recently acquired. It is a fairly nicely refurbished truck with the original 6 volt system. I discovered that the brake lights don't work. He is sure that they did work. I have tested the circuit including the brake light switch and it is good to the point where the harness connects to the tail light bucket. The tail lights both work, but the brake lights do not. I substituted a new bucket with a known good ground attached and the result is the same, no brake lights. Any ideas as to what I am missing?

Re: Need some input on electrical problem
 

Are you saying that you are getting power to the tail light (brake) connector? I'm assuming pos (+) ground? Need to check for power at each point along the circuit starting with the brake switch.
1.) Check for power on the battery side of the brake switch
2.) Check for power on the brake light side of the brake switch and see if it goes on and off with brake application.
3.) Check the next connector down the line between the brake light switch and the brake lights and find where the power is not present (with the brake applied).
There are two ways there can be a problem, a break in the circuit or a short. If power is making it all the way to the brake light socket, then remove the bulb and check the pins in the socket. If there is power to the pins, then there is ether a bulb problem or a ground problem.

Re: Need some input on electrical problem
 

Don't rule out that both bulbs might be blown. Try and test the bulbs off the vehicle. Is this vehicle running flashing turn indicators? (the type that use the brake light?). That can change things.

Mart.

Re: Need some input on electrical problem
 

Could be that the brake light switch which is in contact with your pedal is either all grimed up and needs a good cleaning ( in solvent and let dry good ) and or it needs adjustment ( mounts are slotted ). Mine had the same problem and this fixed it.

Re: Need some input on electrical problem
 

If it's an original setup, his brake light switch is a pressure activated switch directly off the rear of the master, very common problem with these switches. No adjustments can be made. They work or don't work. What JS says is a good way to test it out.

Re: Need some input on electrical problem
 

Thanks guys. Switch is master cylinder mount and is working. Bulbs are good. Back on it this morning.

Re: Need some input on electrical problem
 

If you have signal lights wiring could be your problem.

Re: Need some input on electrical problem
 

okiedokie
# 14 green wire is for brake and dome lights. From circuit breaker, thru brake light switch, to bulb, to ground.
Use test light, starting with circuit breaker for 6 volts.
Bruce

Re: Need some input on electrical problem
 

my suggestion is run a ground wire from the battery directly to the light making sure paint is not on the piece you are bringing the ground wire too. I have a 41 and lack of a good ground can send you in circles
bob

Re: Need some input on electrical problem
 

Turns out that I must have let my tester probe touch the hot side of the stop light switch when I tested it. After getting the truck up on stands with plenty of room to work I found the brake light switch to be bad. The tail lights now work good and bright after I ran grounds from each bucket to the frame. I appreciate all the input.