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Turn signals sometimes turn on


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Hi I have been restoring 1978 280z Datsun and this electrical problem is giving me headaches. When key is turn on to acc, turn signals do not work. No flashing no blinking no sounds what soever. If head lights are turned on when key is in acc, moving the turn signal stick up turns fuel pump on and if stick is moved down to turn on left turn signal no response. If key is put into on position, if the stick is moved up nothing will happen but if stick is moved down left them signal will turn on but not blink. The hazard switch will work with key in both acc and on position but if head lights are turn on with key in either position the hazard switch will stop working. The previous owner was an "electrical engineer" and screwed things up as u can tell. I have cleaned the two big connectors on oassenger side near front of console and no change. The wiring becomes messed up out from these two connectors. If anyone could give me some direction on how to fix this that would be great, thanks.

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There is no possible easy way to fix this with back and forth suggestions. It will be infinitely less trouble to get a (used) wire harnesses for under the dash including to the steering column switches and replace what you have.


Some vehicles have a common problem like a switch that fails and exhibits classic symptoms. Now that can be as easy to repair as suggesting cleaning some contacts. When a previous owner starts re connecting electrical wires to get around a problem, the possible problems caused are practically infinite and equally difficult to solve. 



Fuel pump should not be turned on by a turn signal under any conditions.

Turn signals do not work in accy. position.

Four way flashers should work at ALL times, with or without key.



Maybe someone here might suggest a few things.


Maybe the problem is all in the steering column wiring or switches. Start here.

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Thanks for the reply. I believe the problem is occurring when wires leave the two big connectors on passenger side near the front of the console. If anyone has a picture of that I think I might be able to get something going. I might just have to get new wording harness like you said but that's last resort.

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Wacky electrical problems are almost always caused by grounding issues.  Next most common cause, previous owner "improvements"


Your first step is to get an electrical schematic for your car.   Then as best you can, try to get the electrical system back to stock condition.  Then other people on this, and other forums can help you with specific issues.  If you can get a factory service manual, it may have a separate lights only wiring diagram.  Right now, you are looking  at the electrical system as a whole.  Break it down.  Engine electrical only, lights only, other accessories only.   Break the systems down further, if necessary.  Engine electrical can be broken down to cranking, charging, ignition, fuel pump, and controls (computer) systems.  Lights can be broken down to headlights, parking lights, turn signals, brake lights, reverse lights, side lights, and interior lights.


The hazard signals should work anytime a battery is hooked up to the car.  The turn signals may (probably) get power through the ignition switch being on, and also through the hazard switch, if the hazard switch is off.


If one turn signal lamp is burned out, there may not be enough current flowing in the turn signal circuit to cause the flasher to flash, especially if the connection to the turn signals is weak, or the ground is bad.

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Thank you for the reply. I have looked for A wiring schematic online but I can not find the area of concern. The area where I believe things go nuts is after the two black connectors on passenger side near front of console. If anyone has a picture of this area and where the wires go after those two connectors that would be great. Thanks again for the feed back

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Alright, today I had a battery charger on the car battery and when I did turn the key in on position both time signals light up but do not blink. When hazards switch turns on they both blink. Pretty all I have to do is change blinker they will blink when stick is out in up or down position. The one problem I have is when key is in on position, and head lights are turned on the right tune signal will not turn on but the left one will. If I turn on hazards with key in on position and head lights on the right one will not turn. I'm not sure what could be causing this but as of right now with head lights not on both tune signals turn.

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Swap the hazard and the turn signal flasher units. Does anything change?


Some bulbs share a running lamp and a brake or turn signal. The filament can break and touch and weld to the other filament causing all kinds of grief figuring out what's wrong. I would next check, remove, or replace all front and rear turn signal and running light bulbs.

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Again, check grounds.


"I'm not sure what could be causing this but as of right now with head lights not on both tune signals turn."

When the headlights are on, the headlights may be interfering with the turn signals.  It may also be possible that the tune signal lamp is missing a ground, and is somehow grounding through a headlight, and when the headlight is on, that becomes not possible.


Are the headlights mounted on the fenders?  How are they grounded?  Is it possible the previous owner removed a dedicated ground wire?


Since a 1970 521 has a dedicated ground wire from the headlight lamps to the bolt holding the voltage regulator, I would think the more modern and expensive 280 Z would use the same system. 

How are the turn signals grounded?  Front turn signals on a 521 are grounded to body sheet metal, and the panel the turn signals are mounted on have welds all the way back to the voltage regulator.  The voltage regulator has a dedicated wire to the alternator frame. The alternator frame has a dedicated wire all the way to the battery negative terminal, that is also connected to the engine cylinder head.

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Switched the flasher and now turn signals flash when key is In on position. The right tune signal is a slower flash then the left. When I turn on head lights right turn signal still does not flash. Also I noticed when rurning lights are turned on the light on the right side of the right head lamp is burnt out. Could this be the problem?

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They work! I'm not sure what did it but I took apart side light that was burn out. It wasn't burnt out I had to clean contacts and it worked. I then checked around got grounds to see if everything was connected and I seem like everything was connected (Except ground for right blinker, couldn't find it). I then decided to take turn signal apart and check bulb just incase. I cleaned TS lenses. While all this was happening I had charger on battery. When I tried the blinkers with head lights on they worked. I think the charging of the battery is what did it. Now the only problem if when key is in acc position and I turn right signal on fuel pump turns on.... Ah well gives it character

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