Weird turn signal behavior

[hotsho111]

Hey, I just picked up a 1973 240Z and after taking it out on it's first drive I noticed the turn signals didn't appear to work. After leaving the car parked in the sun for an hour or so when I drove home they were working again

After I got home I was testing all the lights and noticed the left rear turn signal wasn't working. The hazards worked as well (all 4 corners). I couldn't check the brake lights at the time

At some point I was testing the turn signals with the lights on and the turn signals flashed slower and then stopped altogether.

The hazards still work. I tested the turn signal flasher relay by hooking it up directly to the battery and after some fiddling did get it to start clicking. I have continuity at the flasher relay connection when the turn signal switches on (in both directions) but I'm only getting a few mV of power.

While fiddling with the turn signal stock and the relay connector a few times the door ajar buzzer would randomly start or stop working. I think I got the relay to click once or twice while fiddling with all of this but I couldn't confirm on the dash before it stopped again.

I was planning on taking the switch apart to check the rear turn signal but is it possible I have a cold solder joint or something like that which is causing the relay to not get power?

Any thing else to check or does it sound like I'm heading in the right direction?

ETA:  The horn also hasn't worked since I've had the vehicle although the previous owner's salesman said he thought it worked

Edited May 6, 2022 by hotsho111

[siteunseen]

I would charge the battery overnight on 2 amp setting. Sounds like what mine does when the battery is low. The old alternators don't do too well on recharging. I have trickle chargers that really help.

[SteveJ]

If you have an old mechanical flasher relay, what @siteunseensaid is spot on. Over 20 years ago my 73 had the slow to no flash at idle. I swapped out the alternator and did the internally regulated alternator conversion. I never saw the problem again. 

Another way to resolve this is to change to electronic flashers.  I bought this one for my Z cars after changing to LEDs: https://www.amazon.com/gp/product/B0811GTVH2. You have to add a ground wire to make it work, but you can adjust the flash rate, and it gives an audible click.

[hotsho111]

Thanks guys. The battery is fairly new (from February of 2022) so I wasn't thinking it was related to that. Would the flashers still work in the case?

I only have a small .75amp charger but I have another charger (4amp) that should be in soon and I can hook that up

[SteveJ]

What is the voltage at the battery when the car is idling? Like I said, the old mechanical flashers can be picky about voltage.

I forgot to address the horns. When I was waking up my 73 after its long slumber, I tried the horn. Nothing. I took a dremel with a wire brush and scrubbed the contacts on the engine harness and the horns. (I also hooked up the horn that was disconnected.) Both horns worked with clean contacts.

Other possibilities

1. Horn relay
2. The horn button isn't pushing the horn contact on the turn signal switch against the steering column.
3. Fuse

[hotsho111]

I can try and check that tomorrow. I checked the battery with it off and it was a little over 12V

Thanks, I have a feeling it's probably contact related so that was my plan. I tried replacing the fuse first but that didn't change it

I'm at least getting a good understanding of the wiring in the car haha

[Patcon]

A fully charged 12v battery should be 12.7 - 12.8v

If its 12.2, 3 or 4. The battery is low

[hotsho111]

I'll check these things and get back tomorrow.

Does power to the turn signals run through the hazard on 73s? I'm not sure if the turn signals and hazards are connected on a 73? Ie, could a hazard issue be causing a turn signal problem? I've been looking at a handful of wiring diagrams but I'm not 100% sure

I have continuity from the switch but no power so I want to try and work backwards on where the flasher relay should be getting power from

[SteveJ]

When activated, the hazard switch will block the voltage sources for the turn signals and brake lights. However, if the turn signals come on at all, then that is not the problem. Check for 12VDC to ground at the turn signal flasher (driver side) when the key is on. If you have voltage on either side, you can rule out the hazard switch as being a problem.

[hotsho111]

Thanks.

I only got a few millivolts of power at the signal flasher when I checked it.

[dutchzcarguy]

You probably have the usa hazard switch witch has many connections and the turn signal go's through that switch. it can be the culprit.

A euro hazard switch has only 3 connections, a usa has 8-9 wires!  (has to do with the fact that one single light is used for brakelight and the turn signal and hazard.. were the euro only has to switch the (orange) turn signal lamps into hazard lights.

[SteveJ]

8 hours ago, hotsho111 said:

Thanks.

I only got a few millivolts of power at the signal flasher when I checked it.

If your measurements are correct (Sorry, I have helped too many people, including engineers, who can't get proper measurements with a meter, so there is always a measure of doubt when I don't see it executed.), then you need to remove the hazard switch. I advise that before you do the process below, you pull and push on the hazard switch knob a few times and remeasure voltage at the turn signal flasher (with the key ON).

To remove the switch

1. Push and turn on the knob (counter clockwise) and pull the knob off. Be careful not to lose parts. (Been there, done that.)
2. After you pull the knob off, you will need to unscrew the retaining ring. You may be able to use snap ring pliers to get at the holes in the ring.
3. After you remove the retaining ring, you need reach behind the dash to disconnect the optical fiber.
4. Then you have to look up new curse words to reach up further behind the dash and unplug the two connectors, probably with one hand (hence the need for the curse words).
5. Pull the switch out from behind the dash.

Go ahead and reassemble the switch after you remove it, so you don't lose parts.

There are two connectors on the switch. One has 3 pins, and the other has 6 pins. I numbered them in this picture for easier reference.

With the knob pushed in (Hazards off), pins 1 and 9 should have continuity. Also pins 7 and 8 should have continuity.

If they don't, re-check that the shaft of the knob is fully pushed in. You may want to push and pull a few times to see if contacts are dirty. Z Car Source lists the 73 switches as available on a exchange basis for $85.

Reinstalling the switch:

1. Go back to your source for curse words. You will probably need to find some that will guarantee you a spot next to Satan after you pass.
2. Reach up behind the dash with the switch in your hand and fish it through the hole in the dash. 
3. With the skill of a contortionist, reach up with your other hand and start threading the retaining ring.
4. Fumble around blindly to find the 3 pin and 6 pin connectors on the dash harness.
5. Utilizing all of the curse words you looked up in step 1, try to reconnect the connectors blindly with one hand.
6. Having secured your alliance with the Prince of Darkness, attempt to reconnect the optical fiber so the switch will light up at night. (See the reference photo below of the lighter and hazard switch with the light source.
7. Finish securing the retaining ring.
8. Put the knob back in reverse order of removal.
9. Test.

Good luck.