Headlights always on high

[bergcc]

I have been dealing with headlights always on high for a while. Two years ago, they would toggle just fine. Then intermittent "sticking" on high. Now they are there all the time. Here are the things I have confirmed so far:

1) I replaced the signal switch with a used one from Ebay. This fixed issues I seemed to have with my turn signals but not the dimmer.
2) Turn signals and break lights work.
3) Turn signals are a little dim.
4) I replaced the headlight relay with a new part. (no effect)

Anything obvious I can try before I have to trace down a short bit by bit?

[pebbles]

does the hi beam indicator illuminate?

[Nissanman]

There may be a damaged wire in the loom that is energising the relay all the time.
Does the relay click as soon as you connect it?
Here is a little schematic I drew up which may help you diagnose the problem.

1965 SP310 Head Light Schematic.jpg

This is specifically for a 1965 SP[L]310 so be cautious, your wire colours may be different but the principals will be the same.

[garth]

There may be a damaged wire in the loom that is energising the relay all the time.
Does the relay click as soon as you connect it?
Here is a little schematic I drew up which may help you diagnose the problem.

1965 SP310 Head Light Schematic.jpg

This is specifically for a 1965 SP[L]310 so be cautious, your wire colours may be different but the principals will be the same.

Or the relay is NFG and the high and low beam wires have been swapped. Reverse them and if the low beams remain on continuously, the issue is either a defective relay or the relay coil not getting 12v from the toggle switch circuit. You can test the relay in situ with a fused jumper from a 12V source.

Hope you get back to hi lo beam operating!

[Nissanman]

Relay was replaced apparently.

[bakerjf]

Relay was replaced apparently.

I bought a brand new defective thermostat for this car once and spent many hours chasing my tail until I isolated it again, ditched my assumption about it being good, and replaced. Chances are the relay is good, but maybe not. The good news is you don't have to guess, but you're going to have to spend some time with the multimeter.

[DivinDave]

Just had this issue and after much swapping out of relays and checking voltages found that the connector under the dash for the harness to the steering wheel was not fully connected. Once it was, high beams worked properly. Not saying this is your issue but check every connection in the system.

On the wiki are several good wiring diagrams. You really need to have a year specific wiring diagram and just figure out the wiring circuits for the headlights. Trace them down and check for good connections, bad wires, etc. remember that the system grounds the circuit to make the lights and relays work. It just takes time, patience and sometimes a bit of luck.

[fj20spl311]

Post your year in your avatar.
Some years the h/l relay is hot and some its grounded.

I vote for a headlight relay or bad ground.

Can't help you trouble shoot without the year.

[bergcc]

I have a 69-70 311. I will double check the connectors. I found with my new ignition that I had to cut out the connect because the contacts were just not reliable. I was trying to avoid that with my new relay. The connector from the harness seems have all the wires firm. It does appear that I have more room to push the connectors together...it's not clear to me how "tight" I want these. I want them to slide apart later =)

I will remove the plastic parts around the ignition and signal switch today and check the wires again and the harness connector. I seem to remember hearing a click from somewhere when the lights would toggle back on their own. From there, I will try the more aggressive work.

I have the edited wiring diagram for the 69-70 with the colors indicated. It's not perfect, but it got me through my ignition switch swap out.

[bergcc]

Yes, the high beam light illuminates. Forgot to confirm that. It's on when I pull the light switch out and remains on while I toggle between high and low beam. When it was working intermittently I would hear a click then the red indicator for high beam would turn off as expected until it stopped working and remain on.

[fj20spl311]

69-70 wiring can be found at http://www.311s.org/PDFs/1969-70%20Dats ... 20rev9.pdf

Its unusual because the switching is on the ground side.

Look into your bulbs when the lights are on to see if both filaments are lit, that would mean some sort of feed back problem.

At the headlight relay, disconnect the red / black stripe low beam wire and the red/ white stripe high beam wire.
If the lights are still on you have a grounding wire shorted to ground.
With the headlights on, ground each, one at a time to see if the lights work correctly.
If they work then its off to checking the headlamp relay.

[fj20spl311]

Headlamp relay.
Green / blue stripe is hot, if the running lights are working, this wire should be hot from the switch.
Black/red stripe is the ground from the t/s switch....remove that wire and ground the terminal on the relay....it should click and change which wires are grounded to the headlamps. Headlamps should go from low to high

[fj20spl311]

Maybe the first thing to check is if the black/red stripe wire is grounded all the time,
Disconnect that wire at the headlamp relay and see if the low beams are now on.
If it doesn't change to low beams, then the problem is from there to the ground coming out of the T/S switch.
Try disconnecting the T/S switch, if the low beams are now working then the problem is in the T/S switch

[Curtis]

You can use my drawing to see how it is all routed. 69-70 is a beast unto itself. There is about 50 total feet of wire in the headlight wiring.

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

[Curtis]

This might also help. Shows info on the OEM relay and how to wire up a Bosch style relay.

http://www.kendo-usa.org/datsun/69_70_h ... wire_2.pdf