Help with Fixing Turn Signals and Brake Lights

[Armand]

Hey guys,

 

I recently had my dash lights, brake lights, and my turn signals go out in my 1971 240z. I know what your thinking, "Use the friggin' search button." Yes, I have and I read all the threads all about fixing brake lights. So here is a list of things I've already checked:

 

1.) Brake switch- I removed it, routed a 9v battery to it and checked the switch with my multimeter. Brake switch functions properly.

2.) All fuses in the fuse box have been replaced.

3.) The bulbs are perfectly fine, in both the dash and tail lights. Neither has filaments missing. Plus when I flip the emergency switch, the tail lights and lights in the dash come on so the bulbs are working for sure.

4.) I read in one of the threads about a plug with 16 wires on the steering column having corroded or bad connections. I couldn't find any plug with 16 wires but I disconnected all my plugs, checked them for corrosion or bad connections, and re-connected them. They are all perfectly fine. After doing this my dash lights started to work again.

5.) Someone mentioned to push the turn signal up and down with a little force and hold it there. I tried that and had no luck. I ended up blowing the turn signal mechanism's with an air compressor and cleaned everything thoroughly with no luck.

 

Now in the other threads I have searched through, I always read "check your grounds." Can someone be more specific? Which grounds? Where?

 

I also read a lot about checking the fusible links. I tried searching for ones that some people pointed out, but my wiring harness seems to be completely different from anyone else's, and couldn't find anything people were talking about. Can someone tell me how to test these fusible links, and which ones to check?

 

Forgive me if I seem to be ignorant. I HATE dealing with electrical problems and I really really don't want to take it to my mechanic. I just bought my car a little more than a month ago and my parents always give me crap about how I won't be able to fix/install anything on it, and I would need to take it to the mechanic for every little thing.(I'm 16 years old) I already fixed every other thing in the car and don't want to hear any crap from my parents. So help me win. hahah

 

Thanks in advance,

-Armand

[memmert]

First off... testing fusible links. Take an Ohm meter and turn it on. with the red and black leads just in the air you should see infinate resistance. touch them together and you should see zero resistance. Now, touch one end of the fusible link to each lead of the ohm meter, you should now have a big loop of wire... Red wire-fusible link-Black wire (a fusible link is a short piece of wire or that's what it looks like to me of a lighter gauge than the rest of the circuit). With the Ohm Meter on and the loop intact you should still have zero resistance or almost zero and it shouldn't jump around too much if you are being still. Second hold the fusible link in "the loop" and wiggle it around, you still shouldn't get wild sweeps on the resistance some just from moving the leads on the link around but nothing drastic.

 

Second, testing relays. Put your finger on them and get power to them (usually by turning the key) if you feel them click under your finger then they are working. A relay is just a heavy duty switch that completes a circuit, two or three tiny wires go up to it to turn the relay on and off and one big one goes IN the relay and another goes OUT the relay. When current is applied through the tiny wires pull the metal post together it completes the big wire circuit inside the relay and lets power flow to the Fuel pump, headlights, whatever.

The sole purpose of a relay is so you don't have multiple feet of heavy guage wire running through the car which will eat up voltage. If you think of the shortest path between two points lets say a starter and the battery the easiest way to remotely control that circuit is via a relay that is In line between the starter and the battery you simply activate it from where ever it's convenient (in this case the ignition key).

 

 

Like you I had a real hate/fear/distain for all thinks auto electric. I just had a bugger of an electrical problem that turned out to be incredibally simple. So simple in fact that I didn't spend a dime to repair it (well OK I bought some sand paper and dialectric grease) I just kept thinking about the problem and trying new things until I worked it out.

Though I can't tell you anything specific about your problem I can offer this.

Definately get a repair manual I forget the brand of mine but it's the super common soft cover big book for $19.95 or whatever most importantly i has to contain the wiring diagrams (or download them off the Internet) which you probably already have done.

What I did was to literally stare at the friggin things until they made sense to me and held the schematics in hand at the car identifying the green wire and the red wire, etc. The point is I wasn't absolutely sure what was what until I proofed it against the schematic. Once I knew that I started cleaning connectors (like you have started doing).

 

The one thing I always do at work (and home) is troubleshoot problems from one physical (sometimes logical) end to the other and the issue ALWAYS comes up if I look close enough. It may take multiple passes but with each increasing dose of scrutiny I figure something out.

 

What I mean to say is auto electric is not any scarier than any other electric task, in fact i'm finding it's easier cause it's typically well documented if all things are stock.

Simply put I knew I had to figure out when and where juice should flow and when it should not (and how much). Once I figured that out I realized that there were only a few parts in between one end of the car and the other. The long strands were easy to troubleshoot cause either current went through with enough voltage or it didn't and long runs of wire rarely go bad in a car.

So we easily enough have removed the long runs of wire from the equation, next is fuses or fusible links, even if they LOOK good test them. this again is easy enough as they either have minimal resistance or they have infinate resistance (meaning they are bad even if they look good) the same applies with fusible links.

Next we have Relay's (not sure this applies to dash, brake, and turn lights but probably) and since your stuff went out at all the same time look for a relay somewhere in the schematic. It may be sticking. The easiest way to test a relay is turn the key with your finger touching the relay box If it clicks and you can feel it the relay is working.

About the last thing that can get in the way of current flowing from the battery to the lights is a switch so verify each switch works (like A fuse or fusible link I would think, some resistance when engaged and infinity when closed).

 

I am sure you are already light years ahead of me on all this i'm just saying that this is the approach I took and it worked for me. Looking at the whole thing as a problem sucks but looking at each small component is not so daunting. the hardest part is locating or identifying each component and what it does.

 

I've kicked around doing up a quick DVD series on the 280zx since that's what I have on actual fly throughs if the wiring or fuel delivery or whatever systems and identifying each piece and how to troubleshoot it. I am definately not guru but using the same approach it's easy to ask someone about an indivual part but nearly impossible to ask for help on an entire system.

 

 

Sorry so chatty, I am just thinking about your problem and know your pain.

Good luck

[Armand]

Thanks a bunch! That gets me a good idea on a couple things to check. Yes, I do have the Haynes Repair Manual along with "How to Restore a Datsun Z car" and a small blue booklet that fits in my glove box for basic repairs that came with my car.

 

I tried studying the wiring diagrams but I couldn't really identify anything. I think my car might have been re-wired once in it's lifetime, but the original owner passed away and his brother-in-law I bought it from doesn't know squat about the car. I have TONS of wires under the dash that isn't connected to anywhere, can't be found in the wiring diagram, and to make it even worse all the wires are tightly bound together with heat shrink.

 

Thanks for the help once again. I'll check out the relays and clean/check some more plugs tonight. If anyone else can chime in with some answers that would be awesome. Let's try and make this the ultimate turn signal/brake thread to help anyone with these problems.

[memmert]

Well even if you don't recognize anything take off the heat shrink and start just staring down wires and comparing them to the schematics. Even if you don't know what it is you at least will know what it's NOT which often times is just as helpful. You can usually tell what is aftermarket wiring by the look and feel of the wire too. that should help narrow the field a bit.

 

Start back at the tail lights and physically trace the wire all the way back to the battery. The cool thing is that the wire HAS to end up back at the battery AND it HAS to go through a switch, in that discovery you will likely find a fuse or a relay or a short that is the problem. When you approach it that way it will be a brain teaser for sure but easy all the same.

Lastly draw it out on paper as you trace it you will never rememeber all the details so write it down as you trace it and you can study it later when your in the house. Wires that don't go anywhere weren't an issue before so they likely aren't now so don't get too hung up on those.

[VinhZXT]

For earlier Z the brake system is very simple. There is a 12V constant going into one of the wire of the brake pedal switch and the other goes straight to the tail lights. Can't get any simpler than that. Do me a favor and get your volt meter out check the voltage on both wires from the brake pedal switch. If you get 12V coming in and also get 12V coming out when press on the brake pedal this means everything is OK. Then do a continuity check for that wire from the brake pedal to the light bulb. If the continuity checks OK then you have a corroded connection in the power source leading to the brake pedal switch. Check to make sure your fuse is clamped on both ends good. I had this problem on one of my Z awhile back. There is like 6V coming out when press on the brake pedal. I found out that there was a corrosion at one of the connector. So when there is a load on the line it won't provide enough juice. GL.

 

Sorry this is refered to the brake light problem. The signal lights is another animal. Check the flasher switch and the clean the signal switch contacts at the steering column for this problem.

[Paz8]

All good advice for you here, You have two seperate problems, your dash lights, brake lights and four way flashers will operate without the key turned on, the turn signals need the key in the run position to work, two different power sources. As mentioned, check your turn signal flasher unit, check your ignition sw., without the engine running turn the sw. to the run position, is everything else working, heater blower motor, etc., if not jiggle the key around and see if it runs, you could have a bad ign. sw.

[VinhZXT]

All good advice for you here, You have two seperate problems, your dash lights, brake lights and four way flashers will operate without the key turned on, the turn signals need the key in the run position to work, two different power sources. As mentioned, check your turn signal flasher unit, check your ignition sw., without the engine running turn the sw. to the run position, is everything else working, heater blower motor, etc., if not jiggle the key around and see if it runs, you could have a bad ign. sw.

 

Paz8,

Very good point about the seperate power. The flashers and the signals get the power thru the flasher switch. So if the flasher switch is not connected then they all won't work.

[Armand]

Thanks for the help everyone. I really appreciate it. The more the merrier. I will check all the things mentioned when I have some time.

[endurorider]

Check the connections behind the glove box. they run back to the brake lights. Don't trust the voltmeter too much. You may have 12 volts on the meter, but that is unloaded. Use a brake, fog lamp ect bulb to see if it lights up. Thats a loaded circuit test. If it does not you have a voltage drop(bad Connection) If there is green on the terminals use battery cleaner not protector to clean them and squeeze the connector pins to increase tention

Fred