Think I have a short

[KAL7467]

Got the z on sat and since then replaced under hood bulb and glove box bulb did not mess with any other electrical stuff. went to dinner tonight and everything was peachy in the z...on the way home I notice the blinkers don't work so I try the hazards and they work...then I notice that only the spedo was working no other gauges...well the amp meter was in the middle... I assume this is because it taps directly off the battery and the spedo is not electrical...not sure where to start but I think I am looking for a loose connection on a plug...any ideas? thanks in advance

[EScanlon]

Hazards and Flashers each have their own independent flasher unit.

First, check all the grounds in the engine bay. Don't just LOOK at them; remove the screw, scrape off any rust/corrosion, replace screw.

Next, do the same with ALL the fuses in the fuse box. Don't just LOOK at them, pull them out, do a continuity check on them (multimeter check THROUGH the fuse), THEN do a visual inspect to ensure the little wire isn't about to pop off the end cap. Check that the end caps are firm, don't twist off the cap, but DO check that it isn't moving. If any of these are doubtful, replace the fuse.

Before you replace the fuse, take a look at the contacts. Using a small piece of either scotch pad/brillo or a fiberglass brush (contact cleaner) make sure the contacts are shiny bright. Also check that they aren't loose or wiggle, if so, remove the fuse box and peen the rivet tight. Make sure the fuse holders actually GRIP the fuse, not just hold it.

THEN, try everything again and re-post.

E

[Arne]

I'll second E's post above, with the addition that if you don't know the history, I wouldn't even bother testing the fuses, just replace them all. Even if they test good, some of them could be 10-40 years old. (I know some of mine were still original when I bought it.) And old glass fuses tend to be very prone to random failures.

[KAL7467]

forgot to mention that when I pulled into my driveway which is a bump everything started working again on impact...will check all that you mentioned tomorrow when I do a oil change in my shop...

[SteveJ]

Since the car was still running, an easy thing to check would be the wiring harness coming into the car.There should be plugs for the harness under the dash on the passenger side and on the driver side

Also, could you check to see if you still have the following:

Headlights

Running lights

Brake lights

Knowing what you still have could give a clue on where the break is in the circuit.

Also, if you have a voltmeter, check the voltage at the battery with the car off, and then do it with the car on and with someone giving it some gas to get the revs up.

Car off - 12 volts

Car on and about 2000 RPM - 14.5 volts or so

If you live within about an hour and a half of me, I could help you out over the weekend if you need a hand.

[FastWoman]

"forgot to mention that when I pulled into my driveway which is a bump everything started working again on impact..."

Oh no! Those are the worst sorts of problems -- the intermittent ones!

Chances are, if you hit enough bumps and drive the car long enough, the problem will get better for a while, and then when you least expect it, it will leave you stranded a few hundred miles from home. If I were you, I'd keep a multimeter and an electrical diagram (or Nissan Factory Service Manual -- available used on Ebay or Amazon) inside your car. Do a bit of minor disassembly around areas you might do fault tracing (e.g. your steering column cover, fuse box cover). See if you can get the electrical circuits to fail. If/when they do, then go over the car and see where you do and don't have power. Be very gentle, as you don't want to randomly give something a wiggle and have your circuits wake up again. It's easier to find the problem when it's being a problem.

Start with the fuse box, which should already have the cover off. Feel gently for any hot fuse ends. Heat generally means corroded, arcing connections. Clip the negative wire to a body part, and gently start probing all of the fuse *clips* on both sides. Don't pull any fuses out. The clips on each side of any given fuse should have the same voltage. Otherwise either the fuse is bad, or the connection is corroded. The fuse block is divided up into major circuits (e.g. battery, accessory, ignition, lights). If everything is turned on, every terminal in the fuse block should be live. If you have an entire section that's out, the culprit is probably something like a fusible link or a major power switch (e.g. the ignition switch). If EVERYTHING is dead, it's more likely the secondary wire off the positive post of the battery. As Steve suggested, you might be able to trace the problem by asking what all your dead circuits have in common that your live circuits do not.

Edited November 17, 2010 by FastWoman

[SteveJ]

"forgot to mention that when I pulled into my driveway which is a bump everything started working again on impact..."

Oh no! Those are the worst sorts of problems -- the intermittent ones!

Oh come on, Sarah, it's not that bad.

Hitting a bump and "fixing the problem" indicates a loose connection somewhere, quite possibly a ground from the number of systems that malfunctioned. The FSM is your friend. Between the wiring diagrams and the illustrations of the wiring harnesses, you can possibly hone in on the offending circuit(s).

Even if it is just a loose connection, Sarah gives some really good advice for driving around in a car that's almost 40 years old.

[KAL7467]

thanks all will check it out today hopefully the wire chaseing gods will be on my side

[FastWoman]

Yes, Steve, they're that bad! The only times I've ever had to tow my Z were due to intermittent problems -- once with a fusible link in my old '75, and once with the fuel pump wiring in my '78. I much prefer a problem with the common decency to stay broken until I fix it!

I'll mention that the approach I suggest is a diagnostic approach. The other approach you could take is to pull apart all of your connections and clean them up. Then hope that the problem doesn't re-surface. Honestly, that may be the better approach for any old car.

That said, if you don't find the problem in this process, be sure to carry that multimeter and wiring diagram. Heck, I pick up cheap multimeters here and there and have them stashed in cars and boats anyway.

[KAL7467]

o well worked on it a bit and made some progress. the plug going into the pass side of the firewall was corroded and some pins were loose so i re pinned and replaced with new plug. This did not fix the problem but needed to be done. Next I wiggled the wires on the right side of the dash going into the console and click everything went on. Found the fuse that controls those systems(third one up on the left side of fuse block) it was a little warm... then i realized that every time i took the fuse out and back in the ignition relay clicked and everything worked. My thought is that the ancient ignition relay is sticking and causing the fuse to heat up until it finally clicks...so now i am going to replace it with a more modern relay or a oem one if I can find one...any thoughts?

[SteveJ]

The fuse could be heating up due to corrosion. Clean the fuse contacts with emery paper. If you have a Radioshack near you, go see if they carry Caig Deoxit, and clean up the contacts with that. Ensure the fuse is tightly clipped in.

If you look at the circuit on the wiring diagram, you'll see a black wire with white stripe coming off the ignition switch and going to the fuse block. A green wire comes off the fuse and goes to all of the components you were noticing failures on. The fuses can heat up enough to melt the fuse block. As a matter of fact, I was looking at my old melted fuse block to confirm the wire colors. There are no relay contacts that could interrupt the circuit identified in the wiring diagram.

Also, if you need connectors or plugs, check out Vintage Connections. His product line matches up great to the connectors used in our cars. On the other hand, if you have a local supplier who carries the electrical connectors that match the ones in our cars, let me know. I might be interested in buying some.

[KAL7467]

Thanks Steve I will clean them up tomorrow. I came up with the same wire colors when I was tracing the system a bit(need to get my hands on a wiring diagram) so you are saying black/white wire from ignition relay to fuse block then green wire to all the components? The relay that gives the black/white wire power clicks when ignition is turned on but the times that the components don't work the relay does not click...That is why I am thinking it is sticking. I am not sure if that would make it heat up...as for the connectors, I wire and equip police/gov vehicles for a living so my shop has all kinds of connectors...I was not worrying about being period correct at this point just using what I have. If you need any amp pin connectors let me know I have tons.