The Ford Barn

okiedokie · 06-02-2014, 10:17 PM

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?

JSeery · 06-02-2014, 11:07 PM

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.

Mart · 06-03-2014, 02:06 AM

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.

AnthonyG · 06-03-2014, 08:26 AM

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.

Barry-ct · 06-03-2014, 09:00 AM

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.

okiedokie · 06-03-2014, 09:14 AM

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

George/Maine · 06-03-2014, 09:30 AM

If you have signal lights wiring could be your problem.

cmbrucew · 06-03-2014, 09:32 AM

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

Veeder · 06-03-2014, 08:08 PM

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

okiedokie · 06-04-2014, 09:29 PM

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.

06-02-2014, 10:17 PM	#1
okiedokie Senior Member Join Date: May 2010 Location: Tulsa Ok Posts: 519	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?

06-02-2014, 11:07 PM	#2
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	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.

06-03-2014, 02:06 AM	#3
Mart Senior Member Join Date: May 2010 Location: Solihull, England. Posts: 9,239	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.

06-03-2014, 08:26 AM	#4
AnthonyG Senior Member Join Date: May 2013 Location: Pa. Posts: 2,227	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. __________________ Nomad

06-03-2014, 09:00 AM	#5
Barry-ct Senior Member Join Date: May 2010 Location: Newington, Connecticut Posts: 1,374	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. __________________ Barry 50 F-1

06-03-2014, 09:14 AM	#6
okiedokie Senior Member Join Date: May 2010 Location: Tulsa Ok Posts: 519	Re: Need some input on electrical problem Sponsored Links (Register now to hide all advertisements) Thanks guys. Switch is master cylinder mount and is working. Bulbs are good. Back on it this morning.

06-03-2014, 09:30 AM	#7
George/Maine Senior Member Join Date: May 2010 Location: Mid coast Maine Posts: 1,878	Re: Need some input on electrical problem If you have signal lights wiring could be your problem.

06-03-2014, 09:32 AM	#8
cmbrucew Senior Member Join Date: Dec 2010 Location: North of sandy ago, CA. Posts: 2,080	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 __________________ Works good Lasts long time

06-03-2014, 08:08 PM	#9
Veeder Senior Member Join Date: Dec 2012 Location: CT Posts: 409	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

06-04-2014, 09:29 PM	#10
okiedokie Senior Member Join Date: May 2010 Location: Tulsa Ok Posts: 519	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.