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Datsun 510, universal harness in, Bad Headlight switch?


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I have been chipping away at wiring in a universal 12 circuit harness with a modern fuse box. Getting the engine started was actually the EASY part. Lol.

 

In hindsight, The harness manufacturer I chose probably wasn't the best for my application. But I've already cut it up, so I'm gonna make this work.

 

Luckily, their tech support has been remarkable, although they may not be able to help me with datsun specific things, they seemingly know their product inside and out.

 

If I have verified power to the switch, and no voltage to the green/blue wire. Should I be looking for a new switch? I think this is why I have been having so much trouble getting the high beam relay and park lights to operate properly.

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510' s r switched on ground side i think

Definitely! I dont believe that's my issue, I believe I had the relay setup properly the first time I wired it up. only, when I started changing things to figure out the issue it occurred to me I should have tested everything with a multimeter before I modified the original setup...

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The headlamp switch has 2 positions... one click out and a second click out. It has two pairs of wires that it connects.

 

1st position

Parking lamps...

#4 wire Green/White power from the fuse box. It's on or powered at all times.

#3 wire Green/Blue it carries power to the headlamp relay to power the relay (you must have parking lamps for the headlamp relay to work. Without parking lamps you will only have HI beams) It also powers the front parking lamps, front and rear marker lamps, all dash illumination, rear running lamps and license lamp. 

 

2nd position (also connects the same Green/White and Green/Blue wires mentioned above)

Headlamps...

#2 wire connects to White/Red power wire from fusible link to the ignition switch. It's on or powered at all times.

#1 wire Red/Yellow sends power to the two headlamp fuses for left and right sides.

 

When the switch is set to the second position, all four headlamps are powered. HI or LOW beams are determined by the headlamp relay position which selects one ot the other and grounds them to complete the circuit and light them.

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On a stock 510, the headlights are switched on the ground side.

Power is supplied to the common terminal on the headlamps, with two fuses.  If the headlights are off, 12 volts will appear at all three headlight terminals, checking with a test light, or a volt meter.

12 volts will appear at the headlight wires at the original headlight relay.

12 volts will appear at the headlight switch, on the red with a yellow stripe wire.  Again, this is with the headlights off.

 

When the headlight switch is pulled out two clicks, the headlight switch grounds the common terminal on the original headlight relay.  This causes one set of headlights to come on.

 

The coil of the headlight relay gets power from the tail light circuit.  The coil of the headlight relay is grounded at the steering column, by the dimmer switch on the turn signal.  I believe that the normally closed contacts (relay coil not energized) on the original headlight relay ground the high beam headlights, through the headlight switch.

 

Headlight switch test:

Pull the red wire, with a yellow stripe off the original headlight relay.  Take a test light, connect the ground lead on the test light to the positive battery terminal.  Touch the probe on the test light to the engine, or something else that you know is grounded, even the negative battery terminal.

With the headlight switch off, or in all the way, touch the probe on the test light to the red with yellow stripe wire.  The test light should not come on.

With the headlight switch on, or pulled out all the way, touch the probe on the test light to the red with yellow stripe wire.  The test light should now come on.

 

It is possible that the contacts in the headlight switch make contact enough to turn on a test light, but not good enough contact to completely ground the high current the headlamps use.

To check this, you need a volt meter.  Connect the negative voltmeter lead to the negative battery terminal.  With the headlight switch pulled out all the way, check the voltage on the red with a yellow stripe wire at the original headlight relay.  This voltage should be less than .5 (one half) of a volt, or ideally, less than .2 volts.

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Daniel that's not how I see it.

 

First the 12 volts does not get to the headlamps until the headlamp switch is all the way out.

Then it has to go to, and through two fuses then to the headlamps.

 

If the power was on all the time the headlamp relay, which can only be on HI or LOW beams would ground one of them and the lamps would stay on all the time.

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I ALWASY CK N BACK OF THE FUSE BOX TO MAKE SURE THE SOLDER JOINT HAVENT ROTTED OUT.  THEN OHM SHIT OUT.

 

most time its just corrosion.

 

Oh isnt there a ground wire by the light switch near the hood pull handle?

 

Ez to get another swithc I have a few but ez to ohm out

 

ck the highbeam relay also.  if all if low and HIGHS are out when you go to HIGHBEAM then its relay related

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Thank you everyone for the replies! Something I have been dealing with is deciphering datsun language and referencing it to the labels and language for my harness which is designed for a 90s vehicle.

 

The grounding headlights and the high beam relay wire setup is clear to me. Confirmed bad light switch, I have NOS switch on order from Thailand. I'll update when I get it.

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  • 2 weeks later...

I'm a bit unclear on the switch testing procedure. If I get .3v to the green and blue wire i was under the impression at first the switch was in bad working order. Then from this thread I considered I might have mistook that .3v for a faulty switch, when really I just didn't know what I was doing... I still cannot get park lights to operate unless I hook them up to main power.

 

Two things I think a pertinent to mention;

One. I'm using a modern 5 post relay for headlights as I wanted to do away with as much of the dated parts of the electrical that I could.

Two I'm using a universal harness from a company called speedtech, so most of original 510 wiring diagram is moot other than the colors needed to match to the new harness, and the proper dash lights working at the correct time.

 

Any insight on the verifying light switch?

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There are 4 wires to the switch, I don't know if they are numbered on the plug or the switch itself.... but if they are....

 

First pull out position.............. 3 and 4 are connected to give parking lights, dash, side markers, rear running or tail lights and license plate lamps.

 

Second pull out position........ 3 and 4 are connected to give parking lights, dash, side markers, rear running or tail lights and license plate lamps.

.............................................. 1 and 2 are connected to supply power to the 2 fuses for the headlamps

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There are 4 wires to the switch, I don't know if they are numbered on the plug or the switch itself.... but if they are....

 

First pull out position.............. 3 and 4 are connected to give parking lights, dash, side markers, rear running or tail lights and license plate lamps.

 

Second pull out position........ 3 and 4 are connected to give parking lights, dash, side markers, rear running or tail lights and license plate lamps.

.............................................. 1 and 2 are connected to supply power to the 2 fuses for the headlamps

Roger that, as far as I can see on the diagram, first position should give power to the green/blue wire from the switch that links with the park lamps etc. I'm only reading .3v on GR/GL wire in that position. But then, I pull the switch to position two, and headlights turn on. Which indicates I have working power through the switch.

 

Since Low beams and highbeams are switched ground through relay, the park lights are the only thing that gets power from it, correct? I tested my grounds for the park lights and verified they work by connected them directly to power supplying the switch.

 

Doesnt necessarily make sense to get a different switch yet until I can verify if current one is bad, or my wiring is off.

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If parking lights do not work in the first position it isn't the end of the world... as long as they work in the second position with the headlamps on.

 

The headlamp switch has 2 positions... one click out and a second click out. It has two pairs of wires that it connects.

 

1st position

Parking lamps...

#4 wire Green/White power from the fuse box. It's on or powered at all times.

#3 wire Green/Blue it carries power to the headlamp relay to power the relay (you must have parking lamps for the headlamp relay to work. Without parking lamps you will only have HI beams) It also powers the front parking lamps, front and rear marker lamps, all dash illumination, rear running lamps and license lamp. 

 

2nd position (also connects the same Green/White and Green/Blue wires mentioned above)

Headlamps...

#2 wire connects to White/Red power wire from fusible link to the ignition switch. It's on or powered at all times.

#1 wire Red/Yellow sends power to the two headlamp fuses for left and right sides.

 

When the switch is set to the second position, all four headlamps are powered. HI or LOW beams are determined by the headlamp relay position which selects one ot the other and grounds them to complete the circuit and light them.

 

You can pry the switch apart and clean and grease it. The brass tabs are soft and will snap off if bent too far or more than once, but I have done this on several switches.

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  • 3 months later...
  • 2 months later...

okay! I found someone who had a replacement dash harness.  I ditched the universal harness and got everything working, passed inspection, and registered the car.

 

So, the headlights were working, high beams, and HB indicator, everything.   I wired in a modern 5 prong relay on the high beams, and a prefabbed H4 inline harness for the lows, the rest of the under hood lighting wiring is stock in working order.

 

I am still getting intermittent operation from both high and low beams.  The fuses seam to be fine, I have swapped them out with a few different sets to make sure the fuses werent the problem.  Anyone have a suggestion for where or what to start testing?  I have checked the grounds, theyre tight and freshly etched down to metal for good measure.  could it be the relays? how can I test those with a multimeter?

 

any help is appreciated. 

 

EDIT: Also, seems the charge light isnt going off all of the way, its very dim but still on.  reading 14v at alternator and battery at idle

Edited by TheBirdistheWord
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