headlights not working 74' 610

[james610]

my head lights used to wrk just fine until i removed everything, to paint the enginebay (engine, wiring , lights etc...) i put everything back correctly ( im pretty sure) everything wrk except the headlights. when i turn them on i get 12v at the headlight connecter. (both wires theres no ground). the relay wrks i can here it switch on and checked the fuses there good... where are the lights suppose to b grounded at? the wire diagram only shows ground through the relay, where i have it already connected.. any ideas?

[racerx]

maybe this will work:

 

http://www.davidcmurphy.com/olddat/data/dat620-1973.pdf

[banzai510(hainz)]

Im only going to be guessing but assume its close to a 510.

 

when swithc is OFF all 3 tabs should have 12volts on there using a test light that is grounded.or 12volts using a Volt meter.

 

Now when you put the lights ON one of the 3 tabs will go to GRND. The one that losses the 12v/or light is the ground. If you get this it should work and ck your lamp.

 

Try reaseating the relay. Or is it plugged in wrong? 180 deg off?

 

The old volt reg the blk wire grounded?

[james610]

the gound wire is red... i get 12v on all 3 wires but the red wire doesn't ground when the switch is "on"... does the light ground through the relay?

[datzenmike]

I may be wrong but my '74 FSM wiring diagram shows power to the headlights comes in on the Red wire on the right lamps and Red/Blue stripe wire on the left lamps.

 

The low beams filaments are grounded along the Red/Black wire back to the light relay

 

When high beams are selected the relay is energized and the relay disconnects the ground from the Red/Black wire and connects the ground to the Red/White wire which lights both pairs of lamps.

 

Between the light relay and the headlights there are (at least) two connectors on each side connecting the harnesses together. Likely you have forgotten to plug these all in.

[zerow]

There is a ground connection point near the bottom of the right side inner fender. If the connection is bad (read: painted over), the relay has no ground to switch, rendering the lights inoperable.

 

For the sake of arguement, the headlight harness itself has constant positive ( + ) to it, non switchable. Find the correct wire and run a ground wire ( - ) to your lamps. If they turn on, its the ground. If they do not, wiggle the fuse for the headlights and recheck.

[datzenmike]

There is a ground connection point near the bottom of the right side inner fender. If the connection is bad (read: painted over), the relay has no ground to switch, rendering the lights inoperable.

 

Ah but he said the relay clicks. The relay coil is grounded through the same ground. It seems like everything is working so I'm assuming the headlights are simply unplugged.

[zerow]

Ah but he said the relay clicks. The relay coil is grounded through the same ground. It seems like everything is working so I'm assuming the headlights are simply unplugged.

Clicks, but does not get a full completion of the circuit...? Like a starter solenoid...it will click, but not engage fully if the voltage drop is severe.

[james610]

if i run a ground wire the light the light do turn on but there not groounding through the correct wire... so it is a ground wire thats not proberly grounded i just need 2 find it...

[banzai510(hainz)]

I wonder if the contacks in the relay have a HIGH resiaitance.

Maybe open it up and sand the contacks if carbon build up?

 

But but honest I wouldnt think 2 ground contacks would be out at the same time. one for LOW and one for high.

 

Have you turned on the lights. Then hit the High Beam switch? If the lights work then I would think its the Low contack.

[james610]

didnt have time 2 wrk on my lights yet but when the headlights r 'on' the outer lights should b on & when the highbeams go 'on' all 4 lights should b on, correct?

cause i get 12v to all wires connecting to the lights and if i ground the red wire, all lights go on dimly... the relay clicks when i activate the headlights and highbeams but when i activate the headlights(while grounding the red wire) all 4 light go on dimly, highbeam makes the relay click but doesnt affect anything...

[banzai510(hainz)]

When the switch is OFF and you have 12volts on all the light posts in back then its just a corrossion switching proplem. meaning corrssion giving a high resisitance when the relay switches to ground.

[zerow]

You will have 12 volts + constant at one of the posts...I need to get you a pic of mine. I ended up using that AND the switchable ground (who cares the total amount of volts) and running them to a fused relay off the battery. Talk about brighter and better, Nissan should have done this years ago.