Electrical/Grounding issues

[Usain_Boat]

I've been working on getting the electrical side of my '78 280z back to working and have run into a few issues. First off, my low beams do not work and I have confirmed its a grounding issue somewhere between the headlight plug and the switch by grounding it manually which makes them work. This also makes the high and low beams run at the same time which is not good. Second, while I was installing an upgraded wiper motor to replace my broken original one I had the motor working for a few minutes before lengthening the wires for permanent install then it stopped working completely even rewired multiple times. Third, My Blinkers do not work because I don't get power to the turn signal stock. When in the middle position it has 12v but in the two turn positions it has 0v.

I have taken apart, cleaned, and made sure my combo switch works so I don't believe that works. I have also looked at the FSM but I am not sure where to go from here. 

[Zed Head]

6 hours ago, Usain_Boat said:

 First off, my low beams do not work and I have confirmed its a grounding issue somewhere between the headlight plug and the switch by grounding it manually which makes them work. This also makes the high and low beams run at the same time which is not good.

Third, My Blinkers do not work because I don't get power to the turn signal stock. When in the middle position it has 12v but in the two turn positions it has 0v.

Seems like your contradicting yourself in your description.  You said your low beams don't work, then said that they do work.  Sounds like the dimmer switch has a dirty connection.  The headlights work by grounding the power.

Then you said that the stalk has no power, but you measured 12 volts.  The turn signals work by sending power out to the lights, where they are grounded.  So if you have power to the correct place it should get through and out to the lights.  If the lights aren't grounded though, they won't light up.

If you have the combination switch off you can test both of those by measuring continuity at the plug.  You just have to identify the correct pins.

Don't forget that the Hazard switch is part of the signal light circuit.  It has to be working right also.

[Usain_Boat]

I will get to testing continuity but by my lowbeams not working I mean that it usually doesn't work. I spliced into the harness and forced the lowbeams to ground which made them work. by dirty dimmer switch do you mean the rheostat on the dash that controls the backlights? I'm not sure where the dimmer switch would be. I said that the turn signal stock doesn't have power because when I switched it to where it would turn on the flasher and there is no voltage between the solder point on the + and the ground.

[S30Driver]

By dimmer switch, Zed is referring to the turn signal stalk that also controls the hi / lo beam circuit.

Also, closely examine the soldered connections on the top of the combo switch circuit board..  Look for any that have or are about to detach for that board due to heat.

[Usain_Boat]

Ok, I will take a look at that. I know of the FSM wiring diagrams but where would I find the one that Zed attached a picture of?

[Zed Head]

Here is the source of the color wiring diagram - https://www.classiczcars.com/files/category/1-wiring-diagrams/

And the FSM has the schematic of the combination switch.  B is the key.  It's a pain tracing out all of the wires.  I'd draw a diagram of the socket and label each one.  Then take your meter and make sure that you have continuity through the switch when you should.  Also check your grounds to be sure that they actually ground.  The lights are all about the ground circuit.

 

Edited May 17, 2019 by Zed Head
Got screwed up by the link menu requirement. No more pasting.

[Usain_Boat]

So I just traced the low beam ground to both lights and it is conductive all the way. Also, both the dimmer switch and the combo switch have the proper wires switched on when in the position for low beams yet they still don't work. What should I check next? 

Hazards do work now though but not blinkers.

Blinkers work now. I had to take apart the hazard switch and lightly sand the contacts even though it had continuity.

Edited May 19, 2019 by Usain_Boat

[Zed Head]

4 hours ago, Usain_Boat said:

So I just traced the low beam ground to both lights and it is conductive all the way. Also, both the dimmer switch and the combo switch have the proper wires switched on when in the position for low beams yet they still don't work. 

Hazards do work now though but not blinkers.

Blinkers work now. I had to take apart the hazard switch and lightly sand the contacts even though it had continuity.

So you're making progress.  Not clear what "proper wires switched on" means.  Sorry.  Just don't know.  Based on the diagram you should be able to take the pug that connects to the combo switch and jump the wires to see if it's the lights or the switch.  Be the switch.  Make sure you pick the right pins, and use a test light as the jumper if you want to be safe.  The test light will stop you from creating a dead short.

[Usain_Boat]

Sorry, I meant that the switch does what is to be expected based on the wiring diagrams. The proper wires have the proper continuity.

[Zed Head]

Any chance your bulbs are just burned out?  It seems like you've tested the circuit from end to end.

One thing that can happen when testing using a meter is that the meter will measure proper voltage or continuity through an iffy connection (loose or dirty), then when current flows through the circuit the iffy connection gets hot and opens up.  Pretty common for starter problems, because they draw a lot of current.

In your case, since you have high beams, it might be a bad connection at one of the connectors on the way back to the dimmer switch.  It looks like C-2 is on the low beam circuit, it doesn't branch off to the high beam indicator.  Red with black stripe by the color diagram.

Good luck.  It's a tough one.  High and low share the same power source so it has to be on the ground circuit if the high beams work.