Question for those with headlight relays? problem inside

[TBone028]

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 3 days ago after I thought I fixed everything. 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 three days ago. Could I have accidentally overheated the top of the combination switch when soldering causing my current problem? I would think that if that did happen, then it wouldnt have worked Saturday afternoon after I finished soldering. 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 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 and taped 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. looking towards Z-onthebrain

[MikeW]

My parking lights, headlights, and dash lights ARE NOT working. They were working perfectly 3 days ago after I thought I fixed everything. 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 three days ago.

The combination switch is notoriously flaky over time. For a long time I had to turn mine on and off several times to actually get the lights to come on. I eventually took the switch apart and repaired it. I also installed Dave's relay harness to avoid the problem in the future. The fact that you have relays already hopefully indicates that your switch isn't getting damaged more through use but it may have already been borderline. If the switch turns out to be the problem the fix is easy - I posted instructions here almost 5 years ago:

http://www.classiczcars.com/forums/showthread.php?t=17688

[geezer]

If no problem is found at the combination switch, this may help. I'm not sure who to credit for this wiring diagram but it is typical of what you can expect to find.

I think you should revisit what you have recently previously done first. Chances are this new problem is related and will be easily found. The solder connections become tired and corrupted after so many years of high amperage being routed through them before the relays were added.

[vercingetorix]

If the switch turns out to be the problem the fix is easy

My fix was even easier than that... I sent it to Dave, first rate and good as new.

[TBone028]

Thank you all, I think the switch is ok, I ended up taking apart the combo switch last night and cleaned it per the instructions MikeW posted. 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.

[TBone028]

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.

[geezer]

Leave the fuse out, isolating each side of the circuit, to narrow your search. Use a test light connected to a 12V power source. Use the probe to locate where the short to ground is occurring. By unplugging the relay from the circuit you can further isolate sections of the circuit making it easier to pinpoint the short. If the test light glows, the circuit is still shorted to ground. It's never too hard to find, as long as you can define the entire circuit. The relay could possibly be the culprit. If you have no more short to ground (the test light doesn't glow) after removing it, the relay was either shorted or you need to continue testing the circuit beyond the relay.

What did you find when you tested pins 85 & 86 at the relays? Do the relays click when you turn on either the low or high beams? We need more info in order to diagnose. At this point we don't know if the control side of the circuit is at fault or the battery feed.

Edit: A couple of after thoughts. Remove both relays and check for continuity to the fuse box using a multimeter. Let us know what pin it coincides with on the relay. Instead of using a test light as previously instructed, you can use a multimeter instead. I just don't know what equipment you have.

Edited January 29, 2010 by geezer

[TBone028]

Well, unfortunately I dont have a multimeter or test light...I'll get one shortly.

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, so maybe I fudged it up.

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. How do you test that? Side note: does anyone know if the combo switch for the 280Z works in the 240Z?

[geezer]

Because you have a Painless wiring harness installed by a previous owner I supplied a generic diagram showing how the headlight relays would be typically connected. It may or may not coincide with what you actually have. It was meant as just a guideline. I have checked your Profile and reread your 4 posts to find what year and model car you are working on and came up empty. No big deal, but this information will be helpful. The aftermarket wiring alone presents a great deal of mystery for anyone trying to decifer how the circuits were designed/connected by the PO. You will have to spend the time to "define" the circuits. When you get your multimeter you can then start mapping out your circuits by doing continuity tests. Only after having the circuits drawn out so you can understand them, can you begin to troubleshoot a problem with them. Also, the factory service manual (FSM) complete with the wiring diagram would be good to have. There is a link where you can download one free. Maybe someone else can figure out what happened, but myself, without having the car present, I need much more info.

[TBone028]

Sorry Geezer, it is a 1972 240Z.

I guess my question 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 lights and dash lights, 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.

[geezer]

OK, I had a look at the wiring diagram. I only have one for my '70. I drew up a quick example of how the park light circuit works in an attempt to get you on the right track. I just hope the wire colors don't throw you off. Could be different.

I have a combination switch of unknown origin laying loose here that I did a continuity check on. It works the same as my diagram shows.

The pic that you posted is not the same. The way your pic is orientated, the G/W wire should be in the upper left position and the G wire should be directly below it on the left.

The answers to the questions you asked in the last post are:

1 - only if the solder runs to ground somehow

2 - only if the insulation has been compromised

3 - no

3 - yes, because you are only triggering the relays with the switch now

Anyhow, try to get yourself back to square one before you "fixed" anything and try diagnosing the problem again with what you now know. Keep us posted, good luck!

Edited January 29, 2010 by geezer

[TBone028]

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.