I own a 1987 Nissan pickup. My headlight problem is as follows: Driver side low beam and high beam works. Passenger side high beam works. Low beam does not. I am getting 12V between low beam and ground on passenger side until i attach a headlamp. Then voltage drops to zero and no light. All connections look good. Ground should be good since high beam works. I checked out plug that goes into headlamp and thats ok too. Even inserted spade connectors into plug and then tried to light headlamp, no go. Seems like it could be something funky in headlight switch? Unless I can figure this out quickly, I will probably end up just running a wire from driver side headlight to passenger side but its a 15A fuse and I will be getting close to tripping it. thanks for any help. larry
Looks like I found the problem. Bad contact in headlight switch. Took it out, sprayed it with contact cleaner and sandpaper, then reinstalled and it worked some of the time if I turn the lights off and on a bunch. So, appears to be the switch. Thats good. much easier to replace than to continue troubleshooting! larry
I cleaned the contacts on the old switch enough to make it work most of the time. But, went ahead and bought a new switch and now no problem at all. For you info, advance auto had the best deal on the switch. With an on-line discount, it ran around $50, which was less than anythiing else I found and my local store had it in stock.
I've had the same problems before, but repaired the switch. Once the switch is removed, you have to remove a white plastic piece that covers a bunch of metal "fingers" that move up and down to close the circuit. I just cleaned the contacts with sandpaper and it's been running fine since. If it happens again, I might try coating the contacts with copper anti-seize to prevent corrosion.
when i did that cleaning earlier I did get the light to come on most of the time, but not all the time and figured i would just go ahead and replace the switch. I've had this truck for more than 15 years now and have hardly spent anything to keep it going and I don't want to have to worry about whether my headlights are working or not. I'm glad yours is working well. Back in the day I wouldn't have bought the switch either!!