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1976 280Z headlights not working

15657 Views 2 Replies 3 Participants Last post by  pdx280
Z fans:

The headlights on my 1976 280z are not working, either on high or low beam. I am looking for tips on what to check next. I have followed the outline in the service manual, and examined the historical discussion forum search engine, but am now at a stall.

I have tested and confirmed that the two headlight fuses on the engine bay side of the passenger compartment go off and on with the headlight switch. I have also tested and confirmed the four fusable links on the passenger side of the engine bay as I was unsure which one might be tied to the headlights.

I have replaced both bulbs. I have tested the connections to the back of the headlight bulb, and where these connections go into the wiring harness that runs across the front of the radiator. Possibly an important point. On the passenger side, all three contacts within the plastic connecter light up with a 12 volt tester. On the drivers side, none of the three contacts light up with a 12 volt tester.

All other bulbs (back up, side marker, flashers and turn signals) are functioning. All connectors associated with the headlight and turnsignal switch are free of corrosion and seem to fasten tightly. All instrument lights are working, but the high beam interior indicator does not go on.


Are there any grounds between the interior fuse box and the headlight connectors that I need to check, possibly in the engine compartment or up front of the radiator?

Since the headlight switch is turning off and on the interior fuses can I assume that it is not part of the problem?

Does the lack of the high beam indicator turning on give me any tips beyond the fact that the high beams are not working?

What other tests can I perform to isolate the problem?

Best regards,
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Noid lights aren't very good for diagnosing electrical problems.
Basically, the headlight circuit works like this:
The positive terminal of the battery goes to the combo switch. The combo switch goes to the fuse box. At that point the circuit branches through both fuses. Typically it uses a red wire for the right and a red wire with yellow stripe for the left (Dowload a FSM for your car to verify wire colors.). There are two wires that come off each side. One is red with a white stripe (high beams). The other is red with a black stripe (low beams). Those wires go back to the turn signal as return paths for the high and low beams. When you switch from high to low (or low to high), you are changing which wire is in contact to ground, which goes back to the negative terminal of the battery.

This is why it's handy to have a multimeter...
You should have 12VDC to ground at the headlight plugs, but only at the red wire or the red wire with yellow stripe. I suggest testing with both headlights removed to prevent reading the voltage that is backfeeding through a headlight. The backfeed could be enough to light up your noid light, but a meter would probably show the voltage drop. By the way, make sure you are touching a solid ground with the negative lead of a voltmeter. That could have been why your noid light didn't work on the one headlight.

You are likely missing the path to ground at the steering column. The grounds are connected between the turn signal and the combo switch, and the true ground wire goes out through the combo switch. It fits with pretty much everything you described. The BE section of the FSM has all of the information you need for this. All it takes is reading and understanding it, and you'll be in great shape.
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The headlight power also runs through the high/low dimmer switch that is part of the turn signal stalk. Is this a car that has been sitting for a while or have you been driving it and it just happened?

I have had the same problem on the only two Z cars I have owned. In both cases I fixed the problem by spraying contact cleaner in to the dimmer switch at the base of the turn signal stalk, and working the switch. I have only used one contact cleaner, Deoxit DN5, made by CAIG and sold at Guitar Center, so I can't say if the others will work.

On one of the cars, I also had to clean the headlight switch contacts themselves, the ones at the base of the headlight.wiper switch stalk. Also found that I had to recrimp the small circuit board down on to the contacts, it had become loose.

Either way, take the cover off of your steering column, work the switches, and you'll see both areas to focus on. It seems to be a common problem, if the car has been sitting.
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