Right side head lites not working

[dscrib2]

I have an electrical problem and can use some help. My right side head lights don’t work. On low beam the left side is bright but the right side is barely lit. On high beam there is nothing on the right side but the left is good. I have traced wires the best I could and found repaired wires but nothing causing the problem. I replaced both the engine bay & dash harnesses with good used ones because the old ones where hacked into a couple of times. The fuse box was replaced and the light switch was because of the different harness. I made sure that correct wires mated together in the connectors. Swapped turn signal switches & the high beam relay. Yes, I have checked all my grounds and I still have the same problem. Anyone have some guidance?

[dscrib2]

PS The car is a 1969 2K
Dana Scribner

[Curtis]

Unplug the right headlight plug both where it enters the fender and the headlight plug. Check the the solid red wire pin first at the fender for 12 volts and then plug it back in and check at the headlight plug. If you have 12 volts there then the the problem is further on down in the circuit.

This may seem silly but are you sure both filaments in the headlight are good? Bulbs are sneaky.

http://kendo-usa.org/datsun/datsun_head ... _69_70.pdf

[Bwk2000]

I always try the easiest solution first. Unplug your left headlight and plug it into your right harness. If it works fine, it’s just the headlight (you’d be surprised how often that happens). If you have the same issue, follow Curtis’ advice above to trouble shoot further.

[redroadster]

Volts won't tell you amps flow ....though
Which seems low
this is where a amp clamp meter is great
Add a temp redundant ground , after testing the bulb
If no change its on the positive return flow
A lot of times it is in the fuse box as the fuses get hot

[Curtis]

The left plug will not reach the right side. You can get the right plug to the left side. However, if you have moved the alternator to the right side then you'll likely have to disconnect it to try it. Red wire is hot all the time in 69-70. If you don't have a voltmeter then check using any 12 volt bulb from the red to ground.

[Curtis]

If you pull the relay plug you can also check for volts on the red/black wire pin. The thing here is what would normally be the ground connection on the headlight bulb is the hot wire. However remote it probably is the power could feed through the second element and maybe do something funny. Never heard of it but then the 69-70 is subject to all kinds of electrical weirdness.

[Curtis]

I updated the drawing with some notes and call outs. As part of that I changed wire gauges and included a note about the Datsun gauge and US standard gauge.