Half of my headlights stopped working

[dat_sun720]

My passenger side headlights are very dim and barely notice light coming from them. Whereas the one driver side headlight is bright as can be. Could it be that the highbeam headlight is broken? Not really a wiring master.

[datzenmike]

BOTH right side are dim???

 

The last two 10 amp fuses on the far right side of the fuse box are for the headlights. Likely it's the one farthest right (it powers the right side) that is blown. Swap them. If the problem swaps then the fuse was bad.

[Stinky]

I am pretty sure that each headlight has its own contacts in the switch on the column.  That switch is no longer available.  You might be able to clean the contacts w/cleaner spray.

 

The more that I think about it....the above is true.

 

If  you do a search, you'll find a wiring diagram.  That may help you out.

 

The switch part of it can be taken off the column switch w/o taking it off the column.  Spray it down....sometimes it works, sometimes it doesn't.

[datzenmike]

The headlight switch connects one of two fused sources to the right side hi and low and the second fuse to the left side hi and low beams.. Left and right lamps have left and right fuses. The ground side of the lamps goes to a relay that selects a ground path or not. It can only be hi OR low beams. The relay is turned on or off by the hi/low headlight switch.

 

I'd like to know if fixed.

[dat_sun720]

9 hours ago, datzenmike said:

The headlight switch connects one of two fused sources to the right side hi and low and the second fuse to the left side hi and low beams.. Left and right lamps have left and right fuses. The ground side of the lamps goes to a relay that selects a ground path or not. It can only be hi OR low beams. The relay is turned on or off by the hi/low headlight switch.

 

I'd like to know if fixed.

All the fuses are fine. When I turn my high beams on though, all my headlights turn off

[banzai510(hainz)]

that would be the relay contacts.

If it is the same type set up on a datsun 510 it puts a double ground on the lamps one for low and one for high. So I notice its the relay. most oftem.

 

when relay is NOT energized the the GROUND goes thru the ON switch  thru the relay them to the lamp which puts a ground on there.

when in high the relay swithes the ground to the lower lamps and HIghs beams,

 

Power is already on the lamp sockets thru the fuse box.

 

so if you take a volt meter and probe the lamp all 3 connector youll get 12volt (with everything OFF) On high youll get both connectors with 12volts..  then when you switch it youll only see 12volts on one side as the otherside went to ground

 

Japanese cars call this a switrcable ground system.

 

as with the dimming I always ck for dirty connections  or could be carbon on caontaks on relay.

 

as mike said 2 fuses one for one side one for the other.  Lamps can also have elements increase resisitance over time and draw more current I think and cause a fuse to pop but I dont think you have this

Edited December 1, 2022 by banzai510(hainz)

[dat_sun720]

Actually, my headlights go very dim when I put my high beams on, it looked like they turned off when it was bright outside. I tested the relay and it's completely fine

[datzenmike]

1/ With the headlights on, hi or low. Find the RED wire on the relay, make a jumper wire and ground it. If the high beams come on then it's the relay contact inside that's bad. The relay may click but if the contacts inside are bad.....

[Stinky]

If that doesn't work....it is a good idea, go back to my post.

 

If the multi-switch doesn't work right, neither will your lights.

 

I have heard that the relay rarely fails.  

 

We are waiting to hear if it gets fixed.

[Thomas Perkins]

The only problem I ever had with my headlights is that they wouldn't come on.I have new fusible links.The red wire for the lights melted at the the connection.I cut the melted connector out and added a new one and it fixed it.But it gave no warning,didn't dim,just would not work.I have since added new light fittings.I think one of the lights may have gotten wet and caused this.But now nothing is exposed at the lights.What else would cause the red fusible link to get too much current thru it and melt the plastic connector.I replaced them about a month ago,Autozone had them in stock.The rubber parts were dry rotted and one head light was missing the round big rubber cover.I found 2 used ones on Ebay.Like new again.Here are all the connectors going to the lights.I cut them out and put new ones on.On the picture of the fusible link,check the red wire closest to you,you can see a piece of plastic missing,i cut it out there cause the yellow connector was melted into it,i cut the yellow connector out and added a new one.

[Seven Two Oh No]

I would also recommend checking that the bulbs are good. I spent a weekend trying to sort out a very similar issue and it ended up being a defective new high beam I had installed. Didn't think to check it until I was out of other options.

[dat_sun720]

I've figured it out, one of my fuses were blown in a weird way and I changed it out and it started working again. 

[datzenmike]

On 11/27/2022 at 2:24 PM, datzenmike said:

BOTH right side are dim???

 

The last two 10 amp fuses on the far right side of the fuse box are for the headlights. Likely it's the one farthest right (it powers the right side) that is blown. Swap them. If the problem swaps then the fuse was bad.

 

Christ on crutches !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!  this was the first reply. Never trust them by looking at them. Replace or trade with a known working one.

[GDHUMFRIES]

Hello my name is GD Humfries. there are usually 3 reasons why dim passenger headlights. #1. most common is turn signal combonation switch is corroded or burnt contacts. #2. faulty fusible link at battery. #3. bad ground. I offer a mail in rebuild service for turn signal combination switches and hazard/flasher switches. I also sell rebuilt units with 30 day warranty. you can email me at gdhumfries@gmail.com or visit my website www.gdhumfries.com or call direct at our shop at 1 775 800 4720. For the moderator reading this if giving out my website or email is not allowed please let me know I am new to this forum and just want to help.

[datzenmike]

1/ yes it's possible

 

2/ the fusible link is for ALL headlights so wouldn't just affect the right side.

 

3/ The ground is at the headlight relay which selects and grounds either high or low beams. If the ground is faulty it would affect ALL high or ALL low beams not just the right side.

[85 720 king cab 4x2]

where the hell is the headlight relay???? Where is the ground for the headlight relay?….

[85 720 king cab 4x2]

On 11/30/2022 at 8:55 PM, datzenmike said:

The headlight switch connects one of two fused sources to the right side hi and low and the second fuse to the left side hi and low beams.. Left and right lamps have left and right fuses. The ground side of the lamps goes to a relay that selects a ground path or not. It can only be hi OR low beams. The relay is turned on or off by the hi/low headlight switch.

 

I'd like to know if fixed.

Saint please I need help with the relay ground for the headlights I play with my blinker in my left turn signal this come on they used to now they don’t come on at all I gotta rebuild headlights with some JD  Humphries I’m wondering if it’s fried in there somewhere I don’t know??You seem to be the only one that knows how to fix this kind of stuff me where is the relay for the headlight and then where’s the ground for the relay is it it’s a headlight

[DwayneOxford]

It'll be the black one, on R, top of fuse block.

[DwayneOxford]

[DwayneOxford]

[datzenmike]

23 hours ago, 85 720 king cab 4x2 said:

Saint please I need help with the relay ground for the headlights I play with my blinker in my left turn signal this come on they used to now they don’t come on at all I gotta rebuild headlights with some JD  Humphries I’m wondering if it’s fried in there somewhere I don’t know??You seem to be the only one that knows how to fix this kind of stuff me where is the relay for the headlight and then where’s the ground for the relay is it it’s a headlight

 

 

Get a test lamp like this for $5. Clip onto a ground and touch the probe to a wire or fuse and if there is 12v the light inside will light up.

 

 

 

Using Dwayne's handy diagram touch both sides of the two fuses shown. They are at the far right side of the fuse box. They should be 'hot' at all times. Got power???

 

You may have to split the two part plastic clam shell around the steering column to get at the plastic connector to the headlight switch. You should be able to slip the probe down beside the wires and touch the metal pin connectors and get a reading

 

With headlights ON the RL Red/Blue (L is Nissan for Blue) and RB Red/Black wires should show 12v

 

Lets see what you get.