Need a quick blip of know-how!

[gema]

I need to know the cause of this symptom. Electrical gurus, have at it!

As you may already know, the dreaded 3rd fuse down on the right was blowing. I have isolated the short to the front side markers. However, I have reason to believe it is something other than the lamps themselves. Here's what I found tonight when I took my trusty voltmeter into the garage.

The reading on the FR side marker fluctuates between 0 and 10 volts. By fluctuates, I mean jumps every half a second.

The reading on the FL side marker fluctuates between 0 and -10 volts. Negative volts? This is where I get confused.

Now, as previously stated, these lamps appear to be "hard-wired" into the harness by a PO, for reasons I can't decipher. Any ideas as to what might be causing this problem? I'd like to fix it right, but I have my backup plan of running new wires to the lamps themselves, tapping into the headlight switch for power. Of course I would cut no existing harness. So please, if you can lend a hand, do! Once this is through I'm ready to begin the transformation of this Z!

[Ed]

Would that fluctuation coincide with the turn signal relay? Maybe the PO tried to "modify" your marker lights into turn signals? Just a guess.

[EScanlon]

That you are getting a negative volt reading on the LF tells me that the leads have been reversed or that you connected your tester backwards.

With a light bulb, which is essentially what you are checking, the negative voltage is not a factor to be worried about. If you were checking a Relay, a flasher, or some other polarity sensitive item then it would be an item.

That you are getting an intermittent signal, tells me that you are somehow connected to one of the flasher units. Polarity then does become an issue.

You don't mention if the bulb itself flashes when it's on. You need to check that. If the side marker bulb is flashing with either the hazard switch on or the turn signal, then it is wired into the wrong circuit.

The Z has both a Hazard Flasher and a Turn Signal Flasher, so don't assume that they are the same.

Once you've checked the operation of the bulbs with each flasher you can proceed from there.

Hope this helps.

Enrique

[2ManyZs]

I'd definately look into where the PO ran those wires from. I'm wondering if he could have got his power form one circuit and a ground from another such as the turn signal circuit which could be causing part of the problem, especially if there is a short or ground problem on one of those circuits.

[Daniel]

With the sidelites loose from the car use a rag or such to make sure the lights are not touching anything metal . If you put your meter on a good car ground and the other probe touch various metal on the fixture and socket. If you read any voltage you know the ground on the fixture is really a positive. Hook up a test light to car ground and touch the center "hot' of the socket. It better glow. If the pulse you saw is correct, I cant say. Is the car a 240? if yes, then should not pulse. Why do you think the sidelites are your fuse poppers? Do the fuses pop with no bulbs installed in the sidelites? Also I hate to even ask but,we are sure the fuse is the correct one right?

[gema]

That you are getting a negative volt reading on the LF tells me that the leads have been reversed or that you connected your tester backwards.

I tried it both ways, just to be sure. I'm never one to doubt user error. One way it didn't do a damned thing, and the other, fluctuation.

**NOTE** I forgot to mention that the rear sidemarker lamps are plugged in with their original connectors and work like a charm.

You don't mention if the bulb itself flashes when it's on. You need to check that. If the side marker bulb is flashing with either the hazard switch on or the turn signal, then it is wired into the wrong circuit.

I haven't tried either switch, but I will tomorrow. My Hazard Switch doesn't work at the moment. It would be impossible to check if the front markers flash, as once they are connected and I turn the headlight switch on (parking or normal), the fuse pops. It and my interior lights (Dome and Map) are very moody. Turn signals work fine front and rear. Are the sidemarkers supposed to flash with the turn signals?

I'd definately look into where the PO ran those wires from.

I will take some pictures of the wiring tomorrow. It runs into a harness in the very front of the engine bay, and there is no connector or whatnot, just hardwired in.

Daniel: The test light idea is good. Perhaps I could see pulsating current by the glow of the bulb? Yes, I am positive it is the correct fuse, not only through process of elimination, but through many questions asked here and at work. I'll wire them in without bulbs tomorrow and see what happens. Yes, the car is a 1972 240z.

Thanks greatly for the quick replies, all, and I will bring an update (with pictures) tomorrow evening.

[EScanlon]

Are you checking voltage to ground? That is, the red multimeter wire to one of the wires to the light and the black lead to the car's chassis.

If so, then with one wire you SHOULD read a voltage and with the other you won't. The side marker lamps use a wire to the harness to complete the circuit and NOT the mounting screws to the fender.

The side marker lights both front and rear operate with the parking lamps but NOT the turn signals. If they are, then it's a modification by the PO. Although I can see their value when you actually have the turn signal on, but during normal operation they would be off. I don't know if your state does or does not have a requirement on side-marker lights. I do know that they must reflect in all 50 states.

Now for the kicker.

If you are having trouble with the Hazard Light Switch, then STOP!

Before you go "fixing" anything more.

You've uncovered that you do have some form of short. But since the turn signal wiring goes through the flasher as well, and you've already determined an intermittent voltage, I would bet that half your problem is that the Haz. Switch is blooey.

Take it out of the dash.

If it is the illuminated switch with a green lens, push in on the knob, turn 90° and pull out. Then remove the chrome ring at the base. You should then be able to reach behind the dash and disconnect TWO wire connectors, and remove the switch.

The non-illuiminated switch just needs the ring removed, the rest is the same.

This is important to fix first since the two wires connected to the Turn Signal flasher BOTH go through the Hazard Switch. If you have a short in the Hazard Switch you can affect not only the turn signals but the brake lamp as well.

The Hazard switch disconnects BOTH the Turn Signal Flasher and the Stop Light Switch when actuated. When actuated it also connects both front and rear turn signal lights TOGETHER (hence the stop light disconnect and it's positional logic to allow the right brake lamp to illuminate when the left turn signal is actuated).

If your Toggle Style Hazard Switch is loose and doesn't positively click up/down, then you more than likely have a broken pivot point which is causing the short internally.

If it is a Pull Type, then it may have either a cold solder joint or a broken internal contact tray.

Check the switch out and replace / repair it. Once you do that, then you can check the rest of the circuit properly.

Enrique

[Daniel]

I agree the light doesnt use the body as a ground path, My point was since the socket does not insulate the neg part of the socket from the fixture if the hot was incorrectly placed on the neg side the removal and rag insulator would allow testing. Check the status of the inside of the sockets. There is a small disc that holds the hot in place. By correct fuse of course I meant amp size and type.

[gema]

Both the power and ground wires run into the harness from each socket. The readings I got were from bare wire, the sidemarker assemblies are on my table. I did not, however, test the voltage to the ground. I'll do that tonight as well.

I tried to remove my Hazard Switch, and I don't see anything green, so my guess is it's nonilluminated (5/72). I push in...and it doesn't budge. I turn it to the right and hear metal tapping against metal, but still no movement. In other words, it is STUCK somehow. Do I need that "Special Tool" the Service Manual refers to? Or, do I have to somehow get that ring off before I push the switch in? And, if I get the switch disconnected, if it were faulty, would my volt readings to the sidemarkers stop fluctuating? I.E. Would there be any way to tell if the Haz switch was the problem?

[EScanlon]

The NON-illuminated hazard switch is a simple paddle style switch. That is, you flip the lever/paddle UP to actuate it, or DOWN to shut it off.

The Illuminated one, on the other hand, is a round rubber knob with a green lens in it. To operate it, you either pull it OUT to turn it on, or push it IN to shut it off.

In neither case do you TURN the paddle or knob. That you are able to do so tells me that the switch is definitely kaput.

I'll see if I can find some pictures of what they look like.

Enrique

[EScanlon]

Funny, you can't edit a prior post to add a picture, but you can edit a post with a picture and change / delete the picture that is attached.

The picture attached shows both the Hazard and the Fog Lamp Switches. Both are the Paddle Style.

By the way, if anyone can identify item #45, please do so.

I don't have a picture of the Pull Style Hazard Switch. Maybe someone else can post one.

Enrique

[gema]

On that note, how does one remove the ring from around the hazard switch? Mine wouldn't budge. The good news is that the short was in the front left sidemarker. The voltage readings were odd, but when i wired in a different sidemarker, it lit up! So, does anyone have a front left sidemarker I can buy? I just need the socket, i have the lens, gasket, and chrome.