720 no headlights

[firemanbryant87]

Hey, new to the forum and new to Datsun/Nissan in general. I have a 82 720 King Cab and when i got it I never had high beams, but then the low beams started to not work. I read some stuff on here and i cant figure it out. i took out the switch in the dash and i hooked it up to a test light and i get power. When i hook up a leader wire i get power the highbeams worked, (so bad switch for those, its on order) and parking lights/tail lights work (never had the issue) and when i wire up to the low beams i have no issue, but the relay clicks (already replaced the relay, that was the first thing i did). I was thinking its a ground issue but if the beam works with the high beams (4 headlight set up) but not the low it might be something else. i tried to ground it using another leader wire and still not working. I am completely lost.

[datzenmike]

OK

The headlight switch is on the steering column. When in the second position (headlights) it sends power to the two headlight fuses (last two on the far right) in the fuse box. On the other side of the fuses there are two wires a Red/Black to both right side headlamps and a Red/Blue to both left side headlamps. So all headlamps have power. If a fuse is blown only one side will be not working.

 

The headlamp relay simply selects a ground return for either high or low beams. So there are only two possible positions for the relay. It's off position (un-powered) is in the high beam position and when activated it's in the low beams position. If you have only high beams then either the relay is not working or the signal to turn it on (low beams) is missing.

 

The power to the high/low beam relay is supplied by the headlight switch when in the low beam position. This sens a signal to the relay on the Red/White wire. In the low beam position, check for power on the Red/White wire on the headlight relay above the headlight fuses on the fuse box. If there is power then it's the relay. If no power then it's the high/low beam switch on the headlight switch on the steering column.

 

The headlight switch is known to be problematic, usually it's the lubricating grease that dries out or collects dirt. You may be able to flush it out with a contact cleaner in a can if you remove the two part clam shell around the steering column. Move the stalk forward and back while spraying. 

[firemanbryant87]

Thank You. this definitely helps out for the relay issue. I hear the relay clicking so I think that is working. but i cant see the wires behind it. found a wire loose for the right headlight fuse, so fixed that as well. and I'm by passing the switch, I already removed everything and have cleaned the switch but using a small jumper wire. i get high beams to work but no low beams are working. 

[firemanbryant87]

so guessing with power to the fuses its a relay issue. my guess is a wire going to the relay, probably the ground. about to investigate that now, ill keep this updated till i find it in case someone else has the issue. 

[datzenmike]

Relay clicking indicates that it is being told what to do. Might not be making contact inside.

 

If any of the headlights are working then the ground has to be ok because common ground. Remember they all have power..... it's the ground that the relay switches to turn them on.

 

 

[firemanbryant87]

Thanks again for the help. i got them fixed. i re-ran a bunch of wires and all sorts of other stuff to discover due to trying it that the jumper line has to be ran to the high beam and low beam for the switch for it work. I realized it thanks to what you wrote. Thanks for the help it is greatly appreciated!!!