71 240Z High Beams Work Low Beams Don't

[Richie G]

Fiddling today before I put her away for a few weeks and noticed the high work but not the low beams on both sides.  The stalk was in great shape when I last put it together about a year ago but maybe the low grounding in there has an issue?  I really don't have time before my out of town trip to tinker, just curious if there's a list of things I should check when I get back?  All other lights work great just the lows off for some reason.  Could filaments in each bulb go at the same time for some reason?  

[SteveJ]

Considering it's both headlights missing low beam, the most likely problem is with the switch. 

[Richie G]

Thanks Steve, so switch meaning on the turn signal one that changes grounding from high to low right?  I can't imagine why the combo switch would be an issue if its sending power to the lights overall.  I actually think I have an old one of each laying around from a parts bin i can try swapping easily enough to eliminate.

[SteveJ]

Correct, the high/low beam switch on the turn signal stalk.

[Richie G]

On 7/11/2023 at 2:50 PM, SteveJ said:

Correct, the high/low beam switch on the turn signal stalk.

@SteveJ Closing this out, yup was the switch on the stalk.  Luckily I had another from an old stalk laying around.  Swapped and all good.

As i was testing all this I noticed everything on the stalk and the wiper switch works except the high speed on the wipers.  Well i didn't try to washer spray so i guess not everything was tested yet.  When i turn wipers on they do work at low speed but high speed is basically another off switch.  Back to off turns them off correctly.  I ran out of time to pull it back apart but quick glance it did not seem as easy of a swap out of this is a switch issue again.

 

Any advice before i tear things up?

[Richie G]

Tried following the wiring diagram to get a jump on this and I'm confused.  There's two columns for wiper on off with some switch connections it seems.  Off I assume is all three of the Blue, Blue/White, Blue/Yellow should be tied together?  And I'm not sure which speed is high or low but I assume one speed is Blue tied to blue/white and the other is blue only?  Maybe low speed drops out of the three the Blue / yellow and then another click to high drops out the blue/white also only leaving blue?

 

[SteveJ]

There are two basic sources of confusion with the wiper circuit.

1. How does the circuit work? Where does Nissan explain it?
2. What is the actual wiring? 

In looking through the BE section and supplements for 71 & 72, it has this rather confusing diagram.

In Off, the L & LW wires are connected and ungrounded.

When the switch is in 1, the LW and L wires are grounded. The LW wire is the ground for a relay that causes the motor to spin in the proper direction. The L wire is the ground for the low speed.

When the switch is in 2, the LW wire is still grounded, and the LY wire is grounded, too. The LY wire is the ground for the high speed in the motor.

The 72 BE section also has a truth table that backs up my observations.

I am not sure why they show a dotted line connection between the L & LW wires when the switch is in off. From testing, the terminals are connected and ungrounded as I said earlier.

Testing the switch operation:

1. Disconnect the negative on the battery. 
2. Remove the clamshell from the steering column.
3. Remove the headlight switch.
4. You should see a switch assembly on the bottom of the headlight switch. I looked at several in my collection, and the wire colors were consistent. (see below)
5. Set your meter on resistance.
6. Have the wiper switch in OFF.
7. Test YG to YB. They should have continuity. B should not have continuity with any other wire. (For testing, I put the probes on the solder joints on the switch assembly.
8. Put the wiper in Low.
9. Test B to YG and B to YB. Both measurements should be 0 ohms or close to it.
10. Test B to RL. It should have a large number or OL, depending upon how your meter shows high resistance.
11. Put the wiper in High.
12. Test B to YG and B to RL. Both measurements should be 0 ohms or close to it.
13. Test B to YB. It should have a large number or OL, depending upon how your meter shows high resistance.

Report back with your results.

Edited October 30, 2023 by SteveJ

[Richie G]

@SteveJ these are excellent instructions.  thanks so much for such thorough guidance and so quickly.  You're right, this wiring config is probably the most confusing I've come across in my limited time with these cars.  i should be able to get to this in the next day or two will report back.

[SteveJ]

By the way, here is a picture of the switch assembly with the wires. Note the jumper across the middle terminals.

[Patcon]

That would be good info for a "resources post"

"Wiper function"?

[Richie G]

@SteveJ here is what i got.  a lot different than described.  the switch looks exactly the same and i believe i followed instructions except i just realized i disconnected the positive terminal rather than the negative.  you think that's making a difference?

disconnected positive

left switch mounted and connected on all wires

the only thing i notice when twisting the switch is that the ohms drop from 47.5 to 47.3 as indicated in low and high.  reminder, when all connected the switch when put in low position does cause the wipers to function correctly and high position halts them dead in their tracks.  off returns them to the starting position.

Should i go back and also disconnect the negative and start over?

 

 

[SteveJ]

Disconnecting the positive is okay. Disconnecting the negative is safer.

The reason I said to remove the switch was to test the switch and only the switch. If you left the switch mounted in the car and connected, it is still interacting with the circuitry in the wiper motor. By taking the switch out of the car, you're only testing the switch.