Solved!: Rear Lighting Electrical Gremlins Options

[scottthephotog]

So I've been chasing electrical gremlins with the rear lighting since I bought the car a year and a half ago, and from what I can tell, the previous owner was as well (but just didn't mention it during the sale). The front lighting works as it should.

Here are the symptoms:
with the parking lights/headlights off

• The turn signals operate correctly (no pedals or other switches engaged)
• Pushing the brake pedal causes both brake lights and turn signal lights to flash simultaneously
• No reverse lights when in reverse
• turning on the emergency flasher lights flash the licence plate lights.

with the parking lights/headlights on

• Either direction on turn signal flashes both turn signal and reverse lights simultaneously
• pushing the brake pedal causes both brake lights, both turn signal lights, and both reverse lights to flash simultaneously
• turning on the emergency flasher lights cases license plate lights, turn signal and reverse lights to flash
• No reverse lights when in reverse

Things I've tried:

• Cleaning all ground points on the entire car (double checked locations with diagrams on 914World)
• Taillight bulb sockets and connectors are clean
• Checked taillight wiring against diagrams on 914World and shop manuals (I found previous owner had printed out those diagrams as well) - They are correct
• Checked headlight and hazard light switch against diagrams on 914Wolrd and shop manuals - They are correct
• New headlight switch (which it looks like the previous owner tried as he included a spare)
• The previous owner also tried different turn signal flasher relays as I have 2 spares
• The rear wiring looks like it is in good condition. I don't see any splices or breaks.

I know that the hazard light switch is also part of that system. I'm at the point of trying a different one of those, but I don't want to just throw money at random parts.


Any thoughts or suggestions? The front lights work perfectly fine, so I'm leaning towards a wiring issue. Are the front and rear lights split at the hazard light switch that part of the switch could have failed? I also can't figure out why the licence plate lights, reverse lights and brake lights are affected by this.

[framos914]

I agree with Sway-Bar, it does sound like an issue with a short in the rear assembly bulbs or wiring.
Was looking at 73 wiring diagram and all those lights share the same ground point. But voltage for turn and flashers come from Emergency flasher switch. Stop lights, license plate lights, tail lights and back up come from their own separate switches and fuses.
Maybe a good way to troubleshoot is to remove all rear light bulbs and reinstall one at a time. Rear side marker lights also use same ground.
This old wiring can be a pain