Datsun Roadster Forum-311s.org

OK, good news, I have time to work on this today and have help. I actually might need a root canal (not kidding) so that's going to take some of my day...punn avoided (bite into my day). I will post result promptly. Love the diagrams.

Turns out the wiring harness had several ground issues. However, the culprit with the headlight traced back to my partially melted fuse box. My collaborator helped me bypass the fuse with a fused wire and soldered it in place until I can get a new box. He also added an extra ground to help one of the headlights that was dim. Headlights and dash lights all work now.

At the same time, my friend helped me track down about 50 other problems with my wiring. The turn signal switch may still need to be replaced with a new one, but one culprit that just is not working is the damn hazard switch. No power is coming out of it for the turn signals. We hot wired it so I could at least have break lights working but no signals. Funny, when I hit the break, my left turn light comes on. Once I get a new switch, I will see where the signal's are. A new signal switch is like $400 from DatsunParts.com. Trying to avoid that.

Finally, I had a low rpm miss that I just could not dial out. My friend noticed oil leaking from my "new" coil, and noticed it was cracked. "Well", he said, "That here's your problem there..." so he found a suitable after market at a parts store...car purrs like a kitten and I swear the tack is painted on the dial...perfect. The car also pulls all the way to 5k whereas before it lost power at about 4.2k rpm.

Making progress, and learning a lot. That's all I can say. The wiring diagrams made all the difference! Thanks everyone.

The turn signal light coming on when you hit the brakes is a ground problem at the rear lights.

Are you sure you have a 69-70?

Makes no sense that the problem was in the fuse box. Normal for all roadster fuse boxes to melt when the rivet gets loose.
On a 69-70 the same fuse supplies both high and low beams. There are two fuses, one for the left side and one for the right.
How many pins are in the plug for the turn signals?

In the 69-70 if you add a ground at the headlight you negate the whole rest of the system. In order for the 69-70 system to work as designed it has to ground through the headlight switch.

There should be no ground added to the headlight.

As to the turn signal switch, its only function for the headlight circuit is to trigger the relay between high and low. When you flip the switch in the one direction it turns on the coil in the relay and closes the contacts. The parking lights feed the power for the coil in the relay to work. Once you turn on the parking lights then the coil is energized. The turn switch completes the circuit to ground to cause the change.

The coil works independent of the headlight circuits. The headlight power to high and low just flow through the relay.
Here's some shots of the relay.

http://www.kendo-usa.org/datsun/images/relay_69_1.jpg
http://www.kendo-usa.org/datsun/images/relay_69_2.jpg
http://www.kendo-usa.org/datsun/images/relay_69_3.jpg

I think we're going to need some pictures here.

Yes, my friend grounded at the left headlight. Yes, agreed, the coil was a separate problem. I will try to keep focused on the wiring of the headlight circuit. It sounds like I need to remove the new ground, and add/improve the ground to the headlight switch. I can do this myself and share the result. To get things back to previous state, I will hookup the hazard switch again as before to test the result. I will include pictures.

Thank you everyone for your patience and care.

What does your fuse box look like?

Well we have the 68:



Or the 69-70:

I will post pictures soon. I lost a few things in translation. While my friend did test the front light with a local ground, he did not leave it there. He found the problem in the ground back to the switch and fixed it. So my original statement was incorrect. The headlight circuit is whole. I am taking the next steps myself following the circuits back from the hazard switch. Again, pictures to follow.

Curtis, mine is the lower fuse box the 69-70.

Then you better have a look at this.

http://www.kendo-usa.org/datsun/datsun_ ... _69_70.pdf

Headlights and other lights are separate circuits except for the park lights powering the headlight relay.

Lets do this one step at a time.
No need to turn the ign. on.
At the headlight relay, disconnect the red / black stripe low beam wire and the red/ white stripe high beam wire.
Ground each, one at a time to see if the lights work correctly.

If they do not work correctly there is a problem in the fuse box for the side that does not work or the wiring to the head lights from the fuse box.

Open up your headlight relay to make sure all the spade connectors inside are where they should be. I've had an issue where headlights were always on when the battery was connected even without the switch in place. Inside the relay one connector was disconnected and the rest were pushed diagonally interfering with neighboring connectors, and this was a "new" OM relay.
Paul