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Brake light help
- Thread starter ichthos
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The_architect
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Kevin,
I concur with the others.
If your fuel gauge and heater fan, windshield wipers and turn signal are still working it is probably either the brake light switch, a ground, or a bullet connector somewhere.
If you don't have someone to push the brake pedal for you, just jumper the two terminals on the brake light switch. The brake lights should come on.
If those other circuits are not working check your fusebox. Current to all those devices are are carried by one fuse if it is wired per the original diagram.
Congrats on getting it going. It's got to be extremely satisfying!
Charlie
I concur with the others.
If your fuel gauge and heater fan, windshield wipers and turn signal are still working it is probably either the brake light switch, a ground, or a bullet connector somewhere.
If you don't have someone to push the brake pedal for you, just jumper the two terminals on the brake light switch. The brake lights should come on.
If those other circuits are not working check your fusebox. Current to all those devices are are carried by one fuse if it is wired per the original diagram.
Congrats on getting it going. It's got to be extremely satisfying!
Charlie
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One question....are you using DOT5?
In other marques, there has been a HORRIBLE problem with DOT5 and pressure brake switches.
The stuff leaks through and kills the switch.
In other marques, there has been a HORRIBLE problem with DOT5 and pressure brake switches.
The stuff leaks through and kills the switch.
Hook the 2 wires from the brake light switch together, turn on the key, the brake lights should light up.
If they do, it's a bad switch.
If not, check the connections,
Assuming the fuse is good
1) where the rear harness meets the main harness under the right side of the dash.
2) the plugs at the tail lamps
3) the bulbs
If they do, it's a bad switch.
If not, check the connections,
Assuming the fuse is good
1) where the rear harness meets the main harness under the right side of the dash.
2) the plugs at the tail lamps
3) the bulbs
I am using Castrol GTLMA. I have new bulbs. When I hooked up the wires from the brake light switch together and turned on the key, the brakes did not light up. The fuse is good. Does that mean I am left with is a bad connection somewhere? The only place I have been disturbing anything lately is the wiring under the dash. I will check my connections where the rear harness meets the main harness behind the right side of the dash tomorrow. I have not touched the tail lights, so I do not think that is likely at this point. Anything else I should check?
Kevin
Kevin
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Before you go digging too far, make certain you have power (full) on one of those brake light switch wires.
The_architect
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Kevin,
All of this advice is good. You need to do this logically starting at the beginning of the circuit. Here is a yes/no tree. Follow these steps in order:
1) When the key is turned on do the gas gauge, blower and windhshield wipers work? If yes, the break is downstream, at the switch or beyond.
2) Now determine if the switch is good. With the key on you should get 12V at one of the two brake light switch terminals. Put one probe on any ground and one on either terminal to see. It does not matter which terminal gets the 12V.
Now, with the brakes depressed you should get 12V on both terminals. Check it the same way: One probe of your meter on one terminal, the other on a ground. Repeat on the other terminal. If yes, the brake light switch is good.
If no the brake light switch is bad. Replace.
4) If yes, the switch is good and somewhere you have a break in the power to the brake lights. Somewhere a green wire coming from the brake light switch plugs into a green wire with a purple trace. The green/purple is the wire that goes to the brake lights. Make sure these wires are plugged in and both are getting power.
5) If yes, and that connector is connected and getting power with the brakes depressed, there MIGHT be three green/purples going into a connector way back under the deck--I am not sure if this is the case. If so make sure everything is plugged together back there.
6) If you have not cured the problem after following these steps you either have a bad bullet or a break in the green wire or green purple wire somewhere.
If the other lights in the back are working it is probably not a ground. All of these circuits are grounded to the body by the screws that go through the light fixture.
Also! You might have a bullet that looks like it is crimped on correctly, but the wire is broken inside it. I had one of these on a brand new harness. Drove me nuts.
If you follow these steps in order you will find the problem.
Best
Charlie
All of this advice is good. You need to do this logically starting at the beginning of the circuit. Here is a yes/no tree. Follow these steps in order:
1) When the key is turned on do the gas gauge, blower and windhshield wipers work? If yes, the break is downstream, at the switch or beyond.
2) Now determine if the switch is good. With the key on you should get 12V at one of the two brake light switch terminals. Put one probe on any ground and one on either terminal to see. It does not matter which terminal gets the 12V.
Now, with the brakes depressed you should get 12V on both terminals. Check it the same way: One probe of your meter on one terminal, the other on a ground. Repeat on the other terminal. If yes, the brake light switch is good.
If no the brake light switch is bad. Replace.
4) If yes, the switch is good and somewhere you have a break in the power to the brake lights. Somewhere a green wire coming from the brake light switch plugs into a green wire with a purple trace. The green/purple is the wire that goes to the brake lights. Make sure these wires are plugged in and both are getting power.
5) If yes, and that connector is connected and getting power with the brakes depressed, there MIGHT be three green/purples going into a connector way back under the deck--I am not sure if this is the case. If so make sure everything is plugged together back there.
6) If you have not cured the problem after following these steps you either have a bad bullet or a break in the green wire or green purple wire somewhere.
If the other lights in the back are working it is probably not a ground. All of these circuits are grounded to the body by the screws that go through the light fixture.
Also! You might have a bullet that looks like it is crimped on correctly, but the wire is broken inside it. I had one of these on a brand new harness. Drove me nuts.
If you follow these steps in order you will find the problem.
Best
Charlie
I didn't get 12 volts at either terminal, so it looks like I need a new switch. The switch is one of the few things I didn't replace. I guess if it is the original switch, it certainly has well outlived its life expectancy. I'll let you know how it goes when I install my new switch. Thanks for all the help.
Kevin
Kevin
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ichthos said:
ALL STOP!
If you DID NOT get 12V at either terminal, no amount of switches will fix no power!
No power in means there is no way in hades you can get power out!
Key was ON?
Start checking power. Goes to the fusebox. Same terminal as gas gauge, heater motor, and I think wipers.
Most likely connection at fusebox.
You know, I have learned a lot from you guys, but pretty dense in the electrical department still. I ran a continuity tester between the two brakeswtich termnals, and when I pushed in the brake pedal, the continuity meter lit up. Wouldn't that mean the switch is good afterall? If so, what would I check next?
Kevin
Kevin
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Read the post just before yours.
If you have NO POWER on EITHER WIRE with the KEY ON, you have a power delivery problem.
Most likely the connection at the fuse box IF the gas gauge, wipers, and heater still works.
If you have NO POWER on EITHER WIRE with the KEY ON, you have a power delivery problem.
Most likely the connection at the fuse box IF the gas gauge, wipers, and heater still works.
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Do you have a wiring daigram for this car?
Do you need one?
Do you need one?
Sorry TOC, but I didn't see your last two posts when I replied last. So, the continuity meter just shows that the switch works, correct? My gas gauge, wipers and heater still work. The fuses look good still. Should I remove and reattach the wires to the fuse box? If this doesn't fix it, what would I check next? I do have a wiring diagram. I admit I do not understand everything on it. I have to get up at 4:30, so I will have to go at it again tomorrow. Maybe things will make more sense after I have had some sleep.
Kevin
Kevin
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If you used a test light or voltmeter, and tested both wires to a known good ground with the key ON, and have no power on either, follow the stoplight power wire to the fusebox (Green, I think...hard to read) and see if that wire at the box is loose, corroded, or fallen out.
ONE wire looks like it feeds ONLY brake lights....another feeds a "joint" that does other stuff.
Need a diagram?
ONE wire looks like it feeds ONLY brake lights....another feeds a "joint" that does other stuff.
Need a diagram?
Online
Kevin, do you have a voltmeter? If not, you need to get one. Set it to 20 volts and touch one end to the green wire coming into the brake switch (key on) and touch the other end to ground (engine) you should have 12 volts or so.
Another quick test is to touch the green wire to the green/purple wire bypassing the switch - the if there is power, the lights should come on.
If there is no power at the green wire, your problem is between it and the fusebox, (BTW test the fuse for continuity with your continuity tester - just because you can't see the break doesn't mean it is good - don't ask me how I know.
If there is power, and we know the switch is good, find the green/purple wire in the trunk and check it for power (tester to wire and to ground - a bolt will do)
I have a little piece of wire that allows me to bypass the switch completely - a jumper wire will work too, then you don't have to keep pushing the pedal.
If you have power at the green/purple wire, check you light bulbs. You can also check for power through the light socket by touching the bottom of the socket and the sides.
If the bulbs are good and you have power then it is the ground. I'm not sure what Bugeyes are grounded to, but mine ('76) is grounded to the bolts on the light bracket itself.
If the short is between the switch and the fusebox, it really can only be the fuse or the connection to the fusebox itself - clean and tighten the plug.
A third test is to take a jumper wire and run it directly from the battery to the green/purple and see what happens.
you're close, very close!
Another quick test is to touch the green wire to the green/purple wire bypassing the switch - the if there is power, the lights should come on.
If there is no power at the green wire, your problem is between it and the fusebox, (BTW test the fuse for continuity with your continuity tester - just because you can't see the break doesn't mean it is good - don't ask me how I know.
If there is power, and we know the switch is good, find the green/purple wire in the trunk and check it for power (tester to wire and to ground - a bolt will do)
I have a little piece of wire that allows me to bypass the switch completely - a jumper wire will work too, then you don't have to keep pushing the pedal.
If you have power at the green/purple wire, check you light bulbs. You can also check for power through the light socket by touching the bottom of the socket and the sides.
If the bulbs are good and you have power then it is the ground. I'm not sure what Bugeyes are grounded to, but mine ('76) is grounded to the bolts on the light bracket itself.
If the short is between the switch and the fusebox, it really can only be the fuse or the connection to the fusebox itself - clean and tighten the plug.
A third test is to take a jumper wire and run it directly from the battery to the green/purple and see what happens.
you're close, very close!
I won't be home until 6 tonight, but I will report back what I have found. TOC, let me check out what you said first - I don't think I need a diagram yet. John, I do not have a volt meter, but I have a simple battery tester that lights up to show how much voltage there is. Wouldn't this be good enough for my purposes? I can't remember who told me about the continuity tester here, but that sure has been a very useful tool - just need to remember to use it. I am pretty sure there is no power to the switch. I was way too tired to be working on the Bug last night and should have stopped much earlier than I did. I will run through everything again tonight. Thanks for all the help.