Brake lights not working!!

[CarbonBlack240]

I just bought a 260z from a guy and he said that he re-wired the whole car.. BUT more than half of all my wires are cut!! The car runs but I have no brake lights. I tried finding the fuse that connects to my brake switch but no luck. (unless its that little cylinder looking thing right in front of my brake)

According to Chillton all my wires are right.. I have running lights but no brake lights.. Can someone please help me figure out whats wrong??

[5thhorsemann]

First, get a real manual. The Chilton books suck, they are 80% at best. If the PO was into the wiring with cutters and electrical tape, you could be in for a real nightmare. I had a similar experience on an old Nova I had years ago, heres what I did.

First, get a signal toner. Smash a light bulb and insert it into the brake light socket. Connect the toner to the + side of the filiment perch and you can trace the wire through the chassie. This is the most direct aproach. Make sure you get a good toner, weak signal/ strong reciever, a bit more expensive, but much easier to use on a car. Have fun.

[SteveJ]

I just bought a 260z from a guy and he said that he re-wired the whole car.. BUT more than half of all my wires are cut!! The car runs but I have no brake lights. I tried finding the fuse that connects to my brake switch but no luck. (unless its that little cylinder looking thing right in front of my brake)

According to Chillton all my wires are right.. I have running lights but no brake lights.. Can someone please help me figure out whats wrong??

Attached is a picture of the 260Z fuse block cover. That will lead you to the stock position of the fuse. On the other hand, your only other post mentioned having a 240Z. Is this a different car?

Re-wiring a car is usually a warning to stay away from a car. However, now that you're in, let's see what trouble you have. Where did you see the cut wires? Are they hanging loose, or are they covered with tape? What are the colors of the wires & stripes that have been cut?

You could try contacting Zbarn or Zcar Source for wiring harnesses. I'm sure others could provide names for companies that sell used Z parts, as well.

Also, check to see if the right bulbs are installed. They should be dual filament, typically type 1157 bulbs. Single filament bulbs WILL cause issues.

Look at my links for downloading a copy of the FSM.

[Zed Head]

You can narrow things down with a test light or volt meter. You should have power at the brake switch all the time. The wires are (relatively) easy to get to. Just test both wires to ground, with the pedal down and the pedal up.

If you don't have 12 volts on at least one wire with the pedal up (switch open) work your way toward the battery.

If you have power on one wire, but you don't get ~12 volts on the both wires with the pedal down,then your switch needs work.

If you get power to both wires with pedal down then work your way toward the lights.

[FastWoman]

Re-wiring a car is usually a warning to stay away from a car.

Well, I have to think that if someone were scrutinizing my rewiring work, they would give it an enthusiastic thumbs-up! However, I have to agree, in general. I almost always cringe when someone says they rewired something, because in my experience, that almost always means something pretty bad, if not scary and dangerous. In the same spirit, any time I hear "runs good," I automatically translate to "will move under its own power, but needs a LOT of work to run well."

If I were you, I'd start with a general assessment of the PO's wiring skills. If you see wire nuts, hanging wires, twisted connections, connections covered in electrical tape, melted or charred wiring, and generally messy work, you should strongly consider writing off the wiring. It might be fixable, but it's still ancient, so even in an unmolested state, it would still be somewhat crusty and corroded. Your best fix, in the long run, might just be to install a new (reproduction) wiring harness to replace whatever was molested. While you're into it, be sure to do the available electrical upgrades.

The thing is, I can't remember where I saw the repro wiring harnesses, and I can't remember how much they cost.

Edited January 5, 2011 by FastWoman

[CarbonBlack240]

SteveJ.... Is that the fuse cover for the cylinder looking fuses? I'm lost when it comes to any kind of wiring, that's the only thing I havn't mastered.. And yes this is a different car i'm talking about, it's a 74 260. I sold the 240 I had to get this car.

The cut wires were connected to the harness that connects to the tail light assembly. Only the G/W, G/Y and black wires were cut tho.. They were hanging loose and covered in tape pretty much, along with being sodered.

I also have my wire harness from my 240, will that work on the 260?? And how do I know if it's a single or dual filimant bulb? Will it tell me on the bulb itself??

And thank you for your help..

[SteveJ]

SteveJ.... Is that the fuse cover for the cylinder looking fuses? I'm lost when it comes to any kind of wiring, that's the only thing I havn't mastered..

Yes, that is the fuse cover for the glass tube fuses. The fuse box is in the passenger side footwell.

And yes this is a different car i'm talking about, it's a 74 260. I sold the 240 I had to get this car.

Good. I wanted to make sure I wasn't giving you bad information.

The cut wires were connected to the harness that connects to the tail light assembly. Only the G/W, G/Y and black wires were cut tho.. They were hanging loose and covered in tape pretty much, along with being sodered.

Wire colors and location mean everything. Now we can get somewhere.

G/W is 12VDC+ for the running lights.

B is the ground wire.

G/Y is not in the wiring diagram. Are you sure it's not B/Y? B/Y is the 12VDC+ for the brake lights.

I also have my wire harness from my 240, will that work on the 260?? And how do I know if it's a single or dual filimant bulb? Will it tell me on the bulb itself??

And thank you for your help..

The wiring harness from a 240Z isn't a drop-in replacement for the 260Z unfortunately, but hold that thought.

As for the bulbs, take one of the brake lights bulbs out of the socket. (It's the top outboard bulb in the taillamp assembly.) Look at the bottom of the bulb. A dual filament bulb will have two bumps on the bottom. You can look here for an example of the difference between a single filament bulb and a dual filament bulb.

Now if I was to hazard a guess about what happened, I would think that a previous owner had a problem with the taillights or the running light circuit overall. The running light circuit is one of the biggest strains on the electrical system in that there is a weak link in connector for the wiring on the combo switch. In the 240Z it is usually manifested by the fusebox melting down for that circuit. In my 260Z, the connector melted down. As a short-term fix, I replaced the connector. For the long-term, I replaced the exterior bulbs with LED bulbs. Look for the Sold on LEDs thread for more information.

As for what you should do, can you post pictures of the wiring? That could give us an idea of what to suggest for repairs.

By the way, where in GA are you? If you're close enough to me, I could help with repairs.

[mbarjbar]

I would be very interested in a 'reproduction' wire harness! As far as I know, they don't exist. Nearly every British sports from the '50 thru the early '80s have repro wiring harnesses. What is up with that? My '70 is in need.

Mike

[CarbonBlack240]

SteveJ... My fuse box is horizontal from the picture you posted.. So which way would I read that?? And yes I'm sure that it's a G/Y wire, It's like that on the other side as well. I have running lights all around the car, reverse lights, head lights and fog lights. Just no brake lights or blinkers. So I was also wondering if it could be a bad brake switch maybe? My Chillton says I have a fuse connected to the brake switch but all I could find was 2 B/Y wires coming out of the switch. Therefor I am completely confused..

Also, I found a wire in the engine bay that "should" go to my brake lights according to another wiring diagram I found on here. But I cant find where it hooks up. I would post pics but I really don't know how. I have had this account forever but never really figured out how to do anything on here.

When I get home I will look at the bulb and see what kind it is and let you know. And I live in LaGrange.. Inbetween Columbus and Newnan..

[SteveJ]

SteveJ... My fuse box is horizontal from the picture you posted.. So which way would I read that?? And yes I'm sure that it's a G/Y wire, It's like that on the other side as well. I have running lights all around the car, reverse lights, head lights and fog lights. Just no brake lights or blinkers. So I was also wondering if it could be a bad brake switch maybe? My Chillton says I have a fuse connected to the brake switch but all I could find was 2 B/Y wires coming out of the switch. Therefor I am completely confused..

Also, I found a wire in the engine bay that "should" go to my brake lights according to another wiring diagram I found on here. But I cant find where it hooks up. I would post pics but I really don't know how. I have had this account forever but never really figured out how to do anything on here.

When I get home I will look at the bulb and see what kind it is and let you know. And I live in LaGrange.. Inbetween Columbus and Newnan..

First, find an empty metal garbage can. Place it outside and put in about a quarter inch of gasoline. Light it on fire and toss in the Chiltons manual.

The Chiltons manual it HIGHLY generalized. There were a lot of variations in wiring for instance from year to year, especially going from the 240Z to the 260Z and from the 260Z to the 280Z.

You can download a copy of the factory service manual from the link in my signature. That will be much more accurate for what you're working on. If you prefer using a hard copy, send me a PM with your email address, and we can discuss a deal for an extra copy of the 260Z FSM that I have. Anyway, the BE section of the FSM for the 260Z breaks out the different circuits in separate pages to make following the circuit a little easier.

The top of the fuse cover points toward the front of the car.

There are no wires for the brake lights in the engine bay. There is, however, a sensor that will illuminate the brake warning light on the dash. It is wired in parallel to the switch for the parking brake.

What you saw coming out of your brake switch was correct. There should be two B/Y wires. One of those comes off of the fuse box to supply 12VDC+. The other wire off of the switch travels back to the brake lights. NOTE: The wire going to the brake lights passes through 3 connectors on the way. The ground wire coming off the brake lights passes through 2 connectors.

My recommendation to find the problem is this:

Go from one end of the circuit to the other. Start with the fuse box and see if you have voltage on the B/Y wire. You can do that with a noid light or voltmeter. I prefer a voltmeter because you can also look for drops in voltage.

If you have voltage at the fuse, check at the brake switch.

If you don't have voltage on either pin, check the wiring harness connector. (See the FSM.)

If you have voltage on one pin of the switch, press the brake pedal and look for voltage on the other pin.

If the switch is good, then trace the voltage by checking at the connectors going back.

Finally, for posting pictures, make sure you use the Go Advanced button or Quote button to get the advanced features. To attach a picture, click on the paperclip located on the top row of icons. That will open the popup for attaching pictures. There are size limits, so keep the pictures a reasonable size (under 1 MB).

[CarbonBlack240]

SteveJ.... ok so this is what I figured out. I have power to my brake lights, in the back and on my brake switch. According to my voltage meter, when I push the brakes I have no power to my brake switch. And when I let the brake back up I get power back. Any idea on what's going on?

[SteveJ]

SteveJ.... ok so this is what I figured out. I have power to my brake lights, in the back and on my brake switch. According to my voltage meter, when I push the brakes I have no power to my brake switch. And when I let the brake back up I get power back. Any idea on what's going on?

Possibly...

When you were measuring voltage at the brake light switch, were you measuring from one pin to ground, or were you measuring across the switch?

If you were measuring from one pin on the switch to ground & voltage goes to zero when you depress the brake pedal, it could mean a short. Of course, you would expect to blow the fuse in that case.

If you had the voltmeter probes on each pin of the switch, voltage would go to zero when you depress the brake pedal because there is no difference in voltage at the pins. When you weren't touching the pedal, you have a difference in potential and could see a voltage, though I would guess it was less than 12 volts.

Here is what you should have seen, measuring voltage to ground...

Brake pedal up:

Fuse box - 12VDC on both sides of the fuse

Brake light switch - 12VDC on one pin, zero on the other side

Back connectors - zero

Brake pedal depressed:

Fuse box - 12VDC on both sides of the fuse

Brake light switch - 12VDC on both pins

Back connectors - 12VDC