Mystery connector / dash lights / mystery relay / mystery wires - 71 510

[71Ratsun]

Ok all you 510 detectives I have a couple questions I'm hoping u can help with.  I've searched the forums and didn't find the answer to any of these.  I have a 71 510 2dr, that was originally an automatic and has a wiring loom for an auto.   I have headlights in, and front parking / turn signal lights.  Turn signals work.  No taillights yet - they are disconnected.  My questions:

 

1) Dash lights works but are very dim.  I tried twisting the headlight switch, but it doesn't seem to twist.  I know this could be old grease inside keeping it from turning but didn't want to risk breaking it.  My question is did ALL 510s have a rheostat built into the headlight switch, or only some of them ?  Should a 1971 have a rheostat ?

 

2) In the engine bay, near the radiator support I have a 3-prong connector with a green wire, and 2 green/yellow wires.  It's 2 vertical slots, and 1 horizontal slot under them.  Some type of rectangular relay connects to it, I think.  But I don't think it's the horn relay - that one is already clicking when I short the horn button wire, and it's much closer to the fusebox (it has a black, green and green/yellow wire).  Any idea what this 3 prong connector is for ?  I don't see it on the wiring diagram I have.

 

3) Under the dash, right near the hood release and the fresh air vent rod/knob, on the driver side, there is a 2-prong connector hanging down with 2 green wires going to it.  They are arranged like a "T".   Have no idea what this goes to - it's not brake or clutch switch, or turn signal flasher or 4-way flasher.  Those are in place already.  There's hardly any slack in the wires.  I thought maybe it was for the Signex speed sensor thing but everybody says that's on the passenger kick panel (not driver side).   Any ideas ?

 

4) Also under the dash, in the same area, I have a pair of wires coming down (like 2 feet worth) that are black/white and black/green.  Black/white has a female spade connector but black/green is just bare (connector maybe fell off idk).   They appear to be wrapped together and come from up in the harness.  Could this be part of a tach conversion ?  I have a factory tach but can't tell if these wires go up there or not.  May have to remove the dash to find out - but was hoping someone might know before I dig into that.

 

5) Right now, when I turn on headlights, I get nothing on low beam.  When I hit brights, ALL 4 headlights come on.   Is this a low-beam relay issue ? If so where is that relay located and what wires should I be tracing ?  Thanks in advance for everyone's help.    

 

[banzai510(hainz)]

1)my 510 dont have a dimmer switch for the dash lights. I dont recall of being any in 510s

 

2)  is for the dual points set up. Its not needed and can be bypassed. I think the horn relay is on the passenger side of the vehicle(i forgot)

 

3) maybe a door buzzer doom light?????  who cares dont think you need it if you have flashes and turn signals work

 

4) dont know  photos will help

 

5)  if only highs come on My experience its the relay and nees contacks to be cleaned or one can make a new relay work with this if one knows how to wire..

 

Using a test light see if all the 3 connectors has 12volts on there. Grpund light and take pointy end and put in the 3 pronge connector. This means your powered up. then the switch is not passing the ground thru the relay. on HIGH the relay will pass the other ground to both innner and other lamps

 

Of coarse this is a stock wired 510 with no Hack wire jobs or a rewire. Otherwise Im just guessing. Seems 510 owners are elelctrical experts and just ruin them so anybody guess sometimes

[thisismatt]

3) 

 

[71Ratsun]

1 hour ago, thisismatt said:

3) 

 

OMG the temperature sensor.  Now that one is critical, I'm sure.  Thanks - u solved the mystery and I won't be wasting any more time on it.

[thisismatt]

It's not critical, probably removed with the rest of the associated equipment...

[datzenmike]

1/  I agree, I don't think they had a dimmer. Later North American lighting regulations state that all cars must have dim-able dash lights for night time safety. To comply Nissan had to put in a dimmer switch, but where NA cars have very bright dash lights, import cars are too dim to begin with and the switch never gets used once the driver finds that he can't turn the brightness up. A switch that dims an already too dim dash light is just a cruel joke. 

 

2/  Unplug and see if the horn works.

 

3/  Cabin temperature sensor for second set of points.

 

4/ 

 

5/  Either the two low beam filaments are burned out or the relay is not connecting in the off position.  You can pry the metal cover off and pull a folded piece of fine emery paper through the closed contacts to clean them.

[71Ratsun]

Thanks for all the help !  One last question - how do I get the knobs for the light switch and windshield wiper off the shafts ?  I don't see a set screw, is it one of those captive spring loaded button deals where I have to come in the back of the knob with a pick, or something ? 

[thisismatt]

I want to say you have to pull out the knob, then hold the shaft and push/turn...but I could be totally wrong 😅

[datzenmike]

You're right. Pull knob all the way out, grip the stem tightly as close to the dash as you can with vice grips, push in on the knob against the spring and twist 1/4 turn.

[71Ratsun]

You guys are awesome - thanks !