Brake lights not working

[The "A" Team]

Hi, I'm in the process of hooking up the brake lights to my 1930 Model A Coupe, and running into a problem. I purchased a brand new wire harness, brake switch, pigtails and bulbs because the old ones were all rusted and frayed. I installed the new brake switch today, and then tried hitting the brakes after hooking the battery up. Nothing happened. I checked the bulbs and wires by touching them directly to the battery and the brake light lit up. I then checked the wire harness box at the bottom of the steering column and everything seems to be looking good. The headlights, high beams and parking lights light up no problem and the horn sounds when pressed. I also noticed that one time when I put the harness box on incorrectly, the brake lights did light up, but the headlight switch wasn't lined up correctly and I couldn't push the headlight switch as it was stuck. So I don't know what could be wrong that the brakes do not want to light up. Could the wire harness box at the bottom of the steering column be messed up? The wire harness box is the only item I didn't buy new.

Thanks.

 

[JayJay]

I don’t think the brake lights run through the light switch box. The repop brake light switches are problematic. There should be two wires going to the switch - one hot and one to the lights (green with a black tracer IIRC). Jumping them should turn on the lights. The switch should be open between the contacts with the pedal up and closed with the pedal depressed. I’ve had some success opening up the switch and cleaning/polishing the contacts internally.

If the lights go on when you jump across the two switch connectors your issue is likely with the switch.

BTW, rusty exterior on the switch doesn’t necessarily mean the internals are bad. The repops are generally so awful that I’d take most rusty originals over a replacement.

 

[Bob C]

The stoplight switch gets its power from the BAT terminal of the headlight switch.

 

[Patrick L.]

Do you have turn signals ? If so, do they work ?

As said, the brake switch is fed direct power. Check for power to and out of the switch. Check for power at the brake lights with pedal pushed. If there is power to the lights/bulbs then problem is probably a bad ground.

 

[Kurt in NJ]

the connection at the stitch plate— originally soldered, now just push on connector, probably fell off

 

[The "A" Team]

I don’t think the brake lights run through the light switch box. The repop brake light switches are problematic. There should be two wires going to the switch - one hot and one to the lights (green with a black tracer IIRC). Jumping them should turn on the lights. The switch should be open between the contacts with the pedal up and closed with the pedal depressed. I’ve had some success opening up the switch and cleaning/polishing the contacts internally.

If the lights go on when you jump across the two switch connectors your issue is likely with the switch.

BTW, rusty exterior on the switch doesn’t necessarily mean the internals are bad. The repops are generally so awful that I’d take most rusty originals over a replacement.

I jumped the wires, nothing. I took the wires off the switch and held them together and still nothing. It did somehow work when I put the wire box back on the steering column incorrectly, I don't know where the disconnect is.

 

[Tom Endy]

A better idea is to connect the brake light circuit direct to battery power instead of it going through Henry's torturous headlight circuit. It is easy to do. At the brake light switch disconnect the wire coming from the headlight switch, fold it back and tape it off. Run a new wire from the switch direct to power. You can pick up power at the fuse on top the starter or the terminal lugs on the firewall. An added advantage is that if ever out on the road and there is a short in the headright circuit you can disconnect the wire going to it from the alternator or cut-out and get the car back on the road and still have brake lights.

Tom Endy

 

[stickshift]

If the circuit is proper, you should have 6 volts when measuring across the brake switch. That's with the brake lights installed. Use a meter and hook pos. lead to battery pos. Neg lead to either post on brake switch. You should have 6 volts on one of them, nothing on the other. If you don't, trace wire back to source and measure. Try your brake lights out in the tail lamp socket to be sure they are good, I've seen some out of the package with the lead posts offset.
Another note: My brake switch on my '31 has to be in the mid position to be off or "open". One night I noticed that my brake lights were on. I investigated and found the spring had come off. The switch was set up so it was only off when in the middle position. The spring had to be adjusted just right.

 

[The "A" Team]

A better idea is to connect the brake light circuit direct to battery power instead of it going through Henry's torturous headlight circuit. It is easy to do. At the brake light switch disconnect the wire coming from the headlight switch, fold it back and tape it off. Run a new wire from the switch direct to power. You can pick up power at the fuse on top the starter or the terminal lugs on the firewall. An added advantage is that if ever out on the road and there is a short in the headright circuit you can disconnect the wire going to it from the alternator or cut-out and get the car back on the road and still have brake lights.

Tom Endy

I have to be doing something wrong because I'm not getting the brake light to work no matter what. I tried doing what you said and nothing is still happening. How do I test the actual brake light. When I put the 2 wires to the battery the taillight bulb lights up, but not the brake light.

 

[Marshall V. Daut]

In your 1930 Coupe, you should have the brake light switch that mounts to the backside of the center crossmember. There are usually a couple small holes drilled here, sometimes by past owners. Make sure your stoplight switch's plunger passes through the correct hole so that the short brake rod from the brake pedal operates it. Also ensure that the plunger isn't hanging up inside the hole the plunger passes through because of a bent plunger or a mislocated brake light switch.
Marshall

 

[BillCNC]

I have to be doing something wrong because I'm not getting the brake light to work no matter what. I tried doing what you said and nothing is still happening. How do I test the actual brake light. When I put the 2 wires to the battery the taillight bulb lights up, but not the brake light.

A multimeter set on the continuity function. Remove the wires and put a lead on each terminal while working the switch.

Regards
Bill

 

[Y-Blockhead]

Do you have good grounds at the lights? The electrons need somewhere to go after they pass thru your bulbs. Sometimes paint/corrosion needs to be cleaned off.

 

[JayJay]

A Team: I was imprecise in my advice earlier. When I said that the power to the brake light switch doesn't go through the light switch, I meant that you don't have to do anything with the light switch to have the brake lights work. As Bob C's diagram shows, the power comes FROM the light switch, but it's a hard connection from the BAT terminal. And if your headlights work, you are getting power to the light switch.

Power, whereever it comes from, goes to one of the two wires on your taillight (black to the tail light, green/black to the stop light through the stop light switch). Those wires connect to the center terminals in the bulb sockets. From there the power goes through the bulb filament and to the base of the bulb, to the outer portion of the socket, and from there to ground. All the tests you describe seem to indicate that you might have a ground problem.

So: take a voltmeter in "Voltage" mode and put one lead on the chassis (bare metal) and one lead on the power to the brake light switch. If you get a reading, good. If not, you have a problem. Test both wires to the brake light switch this way, one should show voltage and one not. (Battery needs to be connected). If you do get voltage, then the next thing to do is jump the wires on the brake light switch and test the lights themselves. Take your voltmeter and go from the center terminal of the socket to a known good ground. BE CAREFUL NOT TO LET YOUR TEST LEAD GO FROM THE CENTER TERMINAL TO THE OUTER PORTION OF THE SOCKET OR YOU MIGHT GET A BIG FLASHY SURPRISE! If you get a voltage with this test, then you know the power circuit is good. If not, there is likely a break somewhere along the line (maybe from those push connectors under the car).

Next, you test for ground. Take your voltmeter in the "Continuity" mode and test between the socket outer housing and a known good ground on the chassis. Be sure you don't have any paint or grease interfering with the bolts from the taillight to the bracket, from the bracket to the fender, or the fender to the chassis. (The thin gasket between the taillight bracket and the fender should not be an issue if the bolts are all good). Some people put a separate ground wire from the taillight to the chassis to be sure. If you show continuity (no resistance) then you are golden. If not, you have a grounding issue.

I presume that you have the taillight mounted in the car. If not, it won't work because there isn't a way for the current to get from the bulb outer housing to ground (the chassis).

You described "When I put the 2 wires to the battery the taillight bulb lights up, but not the brake light". If you mean the "two wires" coming out of the taillight, neither light should work because you don't have a path from the bulb housing to ground

This should be a relatively easy troubleshooting for someone who is familiar with the Model A electrical system and with a simple voltmeter.

Anyone here live close and can help him out?

Best wishes, and good luck.

 

[The "A" Team]

A Team: I was imprecise in my advice earlier. When I said that the power to the brake light switch doesn't go through the light switch, I meant that you don't have to do anything with the light switch to have the brake lights work. As Bob C's diagram shows, the power comes FROM the light switch, but it's a hard connection from the BAT terminal. And if your headlights work, you are getting power to the light switch.

Power, whereever it comes from, goes to one of the two wires on your taillight (black to the tail light, green/black to the stop light through the stop light switch). Those wires connect to the center terminals in the bulb sockets. From there the power goes through the bulb filament and to the base of the bulb, to the outer portion of the socket, and from there to ground. All the tests you describe seem to indicate that you might have a ground problem.

So: take a voltmeter in "Voltage" mode and put one lead on the chassis (bare metal) and one lead on the power to the brake light switch. If you get a reading, good. If not, you have a problem. Test both wires to the brake light switch this way, one should show voltage and one not. (Battery needs to be connected). If you do get voltage, then the next thing to do is jump the wires on the brake light switch and test the lights themselves. Take your voltmeter and go from the center terminal of the socket to a known good ground. BE CAREFUL NOT TO LET YOUR TEST LEAD GO FROM THE CENTER TERMINAL TO THE OUTER PORTION OF THE SOCKET OR YOU MIGHT GET A BIG FLASHY SURPRISE! If you get a voltage with this test, then you know the power circuit is good. If not, there is likely a break somewhere along the line (maybe from those push connectors under the car).

Next, you test for ground. Take your voltmeter in the "Continuity" mode and test between the socket outer housing and a known good ground on the chassis. Be sure you don't have any paint or grease interfering with the bolts from the taillight to the bracket, from the bracket to the fender, or the fender to the chassis. (The thin gasket between the taillight bracket and the fender should not be an issue if the bolts are all good). Some people put a separate ground wire from the taillight to the chassis to be sure. If you show continuity (no resistance) then you are golden. If not, you have a grounding issue.

I presume that you have the taillight mounted in the car. If not, it won't work because there isn't a way for the current to get from the bulb outer housing to ground (the chassis).

You described "When I put the 2 wires to the battery the taillight bulb lights up, but not the brake light". If you mean the "two wires" coming out of the taillight, neither light should work because you don't have a path from the bulb housing to ground

This should be a relatively easy troubleshooting for someone who is familiar with the Model A electrical system and with a simple voltmeter.

Anyone here live close and can help him out?

Best wishes, and good luck.

Ok, here's an update that will hopefully give some clarity. I connected the positive multimeter lead to the chassis, and then the negative to each terminal of the brake switch. Pictures are attached, picture labeled "right terminal" showed the 6 volts (it says 5.63 V, but my wife took the picture before it went all the way up to 6.15 V), and the picture labeled "left terminal" showed 0.02 volts. When she pressed the brake, both terminals showed 6.15 V. Good stuff so far.

Second, I kept the red meter lead attached to the chassis, and then touched the negative to the bottom of the bulb socket. After my wife pressed the brake, it showed 6.15 V, so the bulb should be getting the voltage to light up. However, after replacing the bulb, and pressing the brake it still didn't light up!

I used multiple bulbs and did check them with the multimeter to make sure they weren't burned out. So, like some other people told me, it might be a grounding issue with the bulbs, since the voltage went through with the positive lead attached to the chassis, but I just don't how to fix that problem.

 

[The "A" Team]

I also just wanted to double-check the bulbs besides using the multimeter. I put the bulbs into a desk lamp and they lit up no problem. I even tried the 12v bulb that was in the desk lamp, just for fun, and that didn't work when the brakes were pressed either. Definitely not the bulbs (I would be super angry at myself if it wound up being the bulbs the whole time).

 

[JayJay]

Ok, here's an update that will hopefully give some clarity. I connected the positive multimeter lead to the chassis, and then the negative to each terminal of the brake switch. Pictures are attached, picture labeled "right terminal" showed the 6 volts (it says 5.63 V, but my wife took the picture before it went all the way up to 6.15 V), and the picture labeled "left terminal" showed 0.02 volts. When she pressed the brake, both terminals showed 6.15 V. Good stuff so far.

Second, I kept the red meter lead attached to the chassis, and then touched the negative to the bottom of the bulb socket. After my wife pressed the brake, it showed 6.15 V, so the bulb should be getting the voltage to light up. However, after replacing the bulb, and pressing the brake it still didn't light up!

I used multiple bulbs and did check them with the multimeter to make sure they weren't burned out. So, like some other people told me, it might be a grounding issue with the bulbs, since the voltage went through with the positive lead attached to the chassis, but I just don't how to fix that problem.

Yup, you have a grounding problem. Good test procedure. You can run a separate wire from the screw that attaches the taillight to the bracket, down through the bracket, and to a location of your choice on the chassis. That should take care of your issue.

 

[JayJay]

Ok, here's an update that will hopefully give some clarity. I connected the positive multimeter lead to the chassis, and then the negative to each terminal of the brake switch. Pictures are attached, picture labeled "right terminal" showed the 6 volts (it says 5.63 V, but my wife took the picture before it went all the way up to 6.15 V), and the picture labeled "left terminal" showed 0.02 volts. When she pressed the brake, both terminals showed 6.15 V. Good stuff so far.

Second, I kept the red meter lead attached to the chassis, and then touched the negative to the bottom of the bulb socket. After my wife pressed the brake, it showed 6.15 V, so the bulb should be getting the voltage to light up. However, after replacing the bulb, and pressing the brake it still didn't light up!

I used multiple bulbs and did check them with the multimeter to make sure they weren't burned out. So, like some other people told me, it might be a grounding issue with the bulbs, since the voltage went through with the positive lead attached to the chassis, but I just don't how to fix that problem.

Yup, you have a grounding problem. Good test procedure. You can run a separate wire from the screw that attaches the taillight to the bracket, down through the bracket, and to a location of your choice on the chassis. That should take care of your issue.

FWIW, this is not uncommon. Ford relied upon all the bolts, etc. forming the ground path but 90 years later that’s not necessarily reliable.

 

[The "A" Team]

Yup, you have a grounding problem. Good test procedure. You can run a separate wire from the screw that attaches the taillight to the bracket, down through the bracket, and to a location of your choice on the chassis. That should take care of your issue.

FWIW, this is not uncommon. Ford relied upon all the bolts, etc. forming the ground path but 90 years later that’s not necessarily reliable.

Man, you guys are good. I'm so glad I joined this forum. In my final test I wrapped a wire around the socket and attached it to the same clip I had attached to the chassis when I did the voltmeter test, and lo and behold it lit up when the brake was depressed!

A small victory. Now I just have to try your solution and see what happens. So just attaching a wire in between the back of the taillight housing and the taillight bracket and then attaching it to the frame will ground the socket(s)?

 

[The "A" Team]

Did I make a mistake by not attaching the taillight housing and bracket to the fender before wiring and testing them? Do the bracket bolts act as a ground for the lightbulbs?

 

[Bob C]

Yes they need to be mounted to get a ground.