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620 turn signal wiring help


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Just need a bit of help of where to start with this because I dont know what's normal and not. Here are the symptoms:


When I turn the right turn signal on there is a 5 second delay then it starts working but seems slow to me.


The hazard lights are also slow and a bit sporadic.


The left wing mounted light doesnt work so I guess that might have something to do with it?


When  the headlights are on, the signal lights are much dimmer.


Finally.... how do you put full beam on!?

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The original flasher unit is load dependent. All lights must be working in order to draw enough current through the flasher to make it work properly. Likewise if you were pulling a trailer with added lights the flasher would speed up. You can buy a more modern electronic flasher that uses transistors and a relay inside that has a sustained flasher rate.


Usually the high and low beams are selected by pushing the turn signal arm towards or away from the dash.


Dim lights are pretty normal I would say. Try jumper cables from a known good battery. If an improvement then your battery is low, needs charging or just old. If not much change in brightness try cleaning the fuse contacts or replacing the fuses. The 620 fuse box is easily unplugged and removed. Wash thoroughly in soapy water and scrub with bristly brush and dry. Select a suitably sized container that you can submerge the fuse box in. Fill with lemon juice and salt solution, scrub and then let sit over night. Rinse and dry in the morning and assemble. The acetic acid removes the old penny patina



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Thanks Mike I will be doing all of this. The 8w bulbs are expensive over here but I have a new set. 5w are mich more common. Once I've got it all working nice US spec, I'm going to convert to UK spec. Flashing side repeaters and no flashing rear brake lights etc

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6 minutes ago, banzai510(hainz) said:

Rev the motor up and see if it get better.you sure the alternator is pumping out good voltage

Not 100% but it is on my to check list. I'll get the fuses changed, and the bulbs and see how it is

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  • 1 year later...

My 521 was like this.  It was bad grounds on mine.  Front and rear signals had shitty grounds.  Cleaned them up and they work fine.  Mine still slow down when idling at a light or intersection, but I also still have a 35 amp alt and also ride with my headlights on all the time to hopefully help keep from getting splattered.


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Every Datsun we work on, we install new heavy duty electronic flasher units (not like original contact point style flasher) on both turnsignal & hazard.  I think most 70's Datsun's used a 2 terminal flasher unit (again, on both t/s & haz).  We use AutoZone's Novita brand part #EL12.  If yours are 3 terminal, Novita does make one, but I don't have the part # for that one!  These heavy duty flashers fix or improve every car we install them in! 😎

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The flashers are load dependent. The more current flowing through them the faster they go. Slower flashing rate would indicate idle voltage is low or corroded bulb holders. You could try a newer solid state flasher that flashes at a set rate. I pull mine from wrecking yard cars.

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.........not disagreeing with checking electrical issues like bad grounds, corrosion on terminals & bulb sockets etc, but you should install new HD flasher units regardless!

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