Question for those with headlight relays? Problem inside

[T-Bone028]

So, after fixing my intermittent dash and parking lights issue by re-soldering a loose connection, I have come across something even more frustrating.

 

My parking lights, headlights, and dash lights ARE NOT working. They were working perfectly 2 days ago. Brake lights, turn signals, hazards, and high beams work. The previous owner installed a painless wiring harness, and at the same time installed relays for the headlights.

 

The relays should fail before the switch fails correct? The switch was confirmed as good two days ago. Does the relay(s) control power for both the parking lights and headlights?

 

The only thing I can think of that I did that could cause this to fail was I pulled out my the mechanical speedometer from my dash to see why it wasnt working, which was just a result of it not being hooked up to the speedo cable. Perhaps I knocked a ground wire loose? I cant think that knocking any wire loose is the cause because all the wiring to the switch in the column is contained in a well wrapped harness, separate from the electrical wires to the speedo.

 

Any ideas as to where to start looking? I pulled fuses to see if any of them were burned out and they all looked good/clean. Would love any feedback or suggestions that anyone can provide.

[roger.svoboda]

the signal wire for the relay coil would come from the stalk switch so that may be the issue. the relays would take power for the lights direct from the battery (or constant source somewhere). At least this would be the logical way to wire. I would start by verifying 12 vdc at the relay contacts. Next find out if you get 12vdc signal at the relay coil when the switch is activated. PO might have been one of those guys who think twisting two wires together with some tape is a solid electrical connection. to test the relay operation just jump 12vdc and ground to the relay coil.

[T-Bone028]

Thank you Roger, I ended up taking apart the combo switch last night and cleaned it per the instructions I've seen posted in various forums. There was corrosion and pitting, but I switched the two plates/tabs so that there was fresh metal for the contacts and cleaned everything up. The switch operates mechanically as it should...its just not getting power.

 

I think the culprit is somewhere in the relays...perhaps one is stuck open/closed? I am honestly a complete idiot when it becomes to electrical issues. I will post back when I test the coils on the relays for power.

[MAG58]

It's really easy to check for a stuck relay... Give it a quick rap with the plastic end of a screw driver. That usually un-sticks it. I have mine tucked away so the water doesn't kill them.

[roger.svoboda]

you are going at it backwards. the switch operates the relay. If you have no power to the switch then you will have no power to operate the relay coil. As I said jump 12v to the relay in question it should click and the lights should come on. But since the last thing you did (always ask yourself that question when stuff stops working) was play with the combo switch I'm thinking you disconnected the power lead to the switch. Look at the top of the relay and you will see a circuit diagram (or should anyway) which show you the contacts and the coil terminal numbers. Again don't discount the PO not making very good electrical connections and one of them pulled apart. two wires twisted together with tape over them is not a secure connection. Ok for testing but after that crimp connector for the lazy. solder and heat shrink for those who want to reduce the failure chances.

[T-Bone028]

Roger, just let me understand this correctly.

 

If I put a jumper on the relay, it should power the headlights, correct? If the headlights come on, then that would mean that I am not getting power at the combo switch, but instead getting power directly from the battery to operate the electromagnet in the relay. So if a jumper on the relay works and powers the headlights, that means that the combo switch itself, is not getting power, and is not actuating the relay to complete the circuit when the combo switch is in the "on" position. In which case I would have to figure out where the power is being lost between the firewall and the combo switch.

 

Am I understanding that correctly? Sorry for the questions, I just want to make sure I understand how it works so I can pinpoint the power problem.

[roger.svoboda]

you got it. if you power the relay and it clicks and you get no lights then the relay conacts have lost power from whatever constant source the PO selected. If the lights come on then the relay is working and wired correctly. In that case the problem is that no 12vdc signal from the combo switch is reaching the relay. This could be no power to the combo switch or the wire from the combo switch to the relay is faulty. given that it was working until you worked on the combo switch I would suspect you somehow lost the power feed to the combo switch. But you need to check everything because there are a lot of variables here. a. is there power to the relay contacts? b. is there power to the combo switch? c. is power getting from the combo switch to the relay. Way out of the box but possible is that the wiring from the relay to the lights is faulty. Have you traced down the wires involved via the schematic in the fsm? Is the relay mounted in a socket and somehow got jarred loose? You are getting light power directly from some constant source thru the relaly - forget the combo switch in this case. The original system was dirrect power to the lights thru the combo switch but that was found over the years to be a poor choice. So the relay only takes like 50 milliamps to operate and will handle 10 amps. solution to the burnt out combo switch. you need to understand how a relay operates. do a google search plenty of elementary descriptions of the operation.

 

When I say jump 12v to the relaly I mean to the coil terminals. one side +12v the other side to ground. polarity is not an issue but be sure what side of the relay coil is grounded check it with a VOM

[T-Bone028]

Ok so after manually checking the fuse box for a faulty fuse, I found one. Unfortunately, the PO switched to a aftermarket fuse box and it is not labeled but thats besides the point.

 

Switched the blown fuse (30 amp) with a good 30 amp fuse, tried to turn on the lights and the new fuse blew. Can a faulty relay(s) cause a fuse to blow? Or would it mean that I have a short or bad ground somewhere in my wiring under the dash? Just trying to pinpoint where to look.

[roger.svoboda]

ground or short and a big one to blow a 30 amp fuse that is enough to fry 16 ga wire. IF it blows after you activate the switch which should activate the relay I'm guessing the wiring to the lights has got some real issues. but again you said you only messed with the combo switch wireing so maybe you just shorted the power lead to the relay. Yes the relay can be bad but just remove it from the circuit and activate it with jumpers this will tell you what is wrong. You really need to learn some basic electricity google search on the web will tell you all this with pretty pictures.

[T-Bone028]

It doesnt seem to be my headlights that is causing the short or fuse to blow, but instead my parking lights / dash lights.

 

 

What I found was on the top of the combo switch (ignore the red writing, I took this image from another forum), if I removed the wire on the top left (which I believe is the power for the parking lights and dash lights?) then my headlights come on when in the correct switch position. The fuse does not blow. I had originally re-soldered the wire on the top left this past weekend, so maybe I fudged it up? I tried re-soldering it again tonight, but it still blew the fuse in the parking light position on the combo switch.

 

I've tried tracing all the wires and the connections look good. I took apart the combo switch 2 nights ago, and cleaned it really well and removed all the corrosion and traded contact sides for fresh metal like in the instructions found in this forum. I'm somewhat hesitant to buy a new combo switch, because I'm unsure if it is the problem. Side note: does anyone know if the combo switch for the 280Z works in the 240Z?

 

And yes, Im still trying to learn as much as possible how electricity flows. Its confusing me to no end. Thanks for your insights Roger, it is helping me understand despite my lack of problem solving ability.

[roger.svoboda]

you need to get a vom (VoltOhmMeter or multimeter) and learn how to use it. Get a pretty good one at Harbor Freight under $20. Invaluable for troubleshooting elecrical problems. Digital or Analog I like the analog better for what you are doing and they are cheaper. If you know a bunch about electricity the digital does somethings better.

[T-Bone028]

Picked up a multi-meter this morning...will report back what I find after I do some tests.

 

I guess my question now is, what else can cause a wire to short, or a fuse to blow? I've been trying to wrap my head around this, and figure out what is causing it. I've checked every connection from the console to the fuse box and forward. I cannot find any thing that is not well connected and securely wrapped and contained.

 

The way it looks like the PO set up power to the parking light circuit, was by tapping into the headlight power supply. I know the headlights on my car are set up on a relay, but I'm unsure about the parking lights.

 

1) Can a bad solder job cause a wire to short?

2) When soldering, if the wire gets heated up too much by the soldering gun, can that cause the short?

3) If the parking lights power supply is run off of the headlight power supply, and the power supply wire for the parking lights is using a much thinner gauge then the power supply for the headlights, can that cause a short?

3) If a relay is added to the parking lights, that should decrease the amount of power going through the switch correct?

 

I understand that I am an infant when it comes to electrical systems. Just trying to learn so I can understand, fix, and know what to do in the future.

 

FYI, I decided that throwing parts at the car is a method I cant deny. I purchased the parking light relay harness from MSA. I'm hoping that it might "cure" the problem. And if not, then at least once it is fixed, I have a relay operating the parking lights, dashlights, running lights, etc.

[roger.svoboda]

1,2,3 and 3. NO. Ashort is a hot wire touching another wire that is grounded or goes thru a grounded device. A ground is a hot wire physically touching ground (in this case the car frame and body. You need two wires to make a circuit one to supply electricity and one to bring it back to the source. In automotive circles the frame/body is used as the second wire. EX: A +12vdc wire goes to a light bulb terminal the other terminal is connected to ground thru a short piece of wire from the other terminal thus completing the circuit and lighting the light. A relay is simply a device that connects this circuit by means of a small coil current closing some contacts (switch). The relaly only uses coil current regardless of how much current it supplies to the lights thu the contacts. until you decide to study electricity you are stumbling around in the dark.

A fuse blows when too much current flows thru it.

[sweetleaf]

Remember the painless harness is probably not installed exactly like stock. You said when you removed the lead on top of the headlight switch , they worked correctly. And when you reconnected it it blew the fuse. You are going to have to manually test/trace the other wire to see how it is hooked up. It may indeed be run to the parking lights, but you may have a short to ground. Use your VOM and test the resistance between that wire and a good ground point on the car. That should tell you if you have a direct short to ground.

[T-Bone028]

So, after really thinking about it and taking the advice of starting with the thing I last "fixed", I was able to find the culprit. It was my own mistake when soldering. Part of the wire, on the top left of the combo switch that I had THOUGHT I had properly re-soldered, was partially touching the metal combo-switch housing, causing the short. I ended up re-positioning the exposed wire, so it was only touching the correct terminal, and wrapping the wire with electrical tape to make sure no bare wire was exposed for future mishaps.

 

Sometimes the easiest things are the most often overlooked. Thank you for everyone's input, it has helped me gain a better understanding of how relays and general electrical wiring works, and has helped me familiarize myself with both the painless wiring harness in my car and the stock datsun switches.