Wiring mystery on my 74 .18

[InkyP]

Just bought this car and redoing the interior and most of the seals. While I have the back window out I want to add turn signal and stop lights near the top of the back window. I found the right wires for turn and stop but as I was testing some thing weired was happening. I have spliced in to the wires but have not hooked them up yet.

Weirdness:

Key off> click left turn on and the rear left running light and left brake light comes on. Next turn right and the rear break lights come on both sides. Turn the lights on both brake lights and left turn signal light come on.

Key on> turn the lights on and the break lights come on. Both left and right turn signals work fine. Emergency blinkers work fine. Break light works fine with lights off.

My question is could these issues be due to someone wiring the turn signal column up wrong? I did find a broken turn signal lever under the seat so I am thinking someone replaced the column.

[Drew_Dye]

This sounds a WHOLE lot to me like the turn signal was replaced and the person who did the wiring job did a less-than-stellar job. For starters, I don't think your turn signal lever is supposed to have ANY effect when the ignition switch is in "off".Though I haven't yet gotten to explore this part of my 914, my experience with a turn signal switch on another car taught me a few things that are no doubt universal.
When replacing the switch assembly, my new switch didn't include the plastic connector that all the little electrical contacts snap into and the going recommendation is to swap wires one at at time. When you're dealing with fifteen individual connectors, this can go south very quickly if you're careless and try to do them all at once. I thought I had been pretty careful and still got the emergency flasher and brakes lights swapped around.
Everything, including the brake lights goes through the turn signal assembly. The turn signal assembly acts as a traffic cop and directs the electricity to the road it needs to take to get where it's going. Once the electricity goes out the other side of the turn signal switch assembly, it just follows the road it's on because there are no side streets to take at this point (unless you have a short, and that's another discussion).
I will sit down with the wiring diagram in my trusty Haynes manual later and make any corrections to the information above as required.

[Dave at Pelican Parts]

The 72+ 914s do have a plastic plug for the turn signal switch.

When the ignition is off, the TS switch operates the "parking light" feature, where the side markers on that one side go on. (Good way to kill your battery, BTW.)

It sounds like there are wiring issues, but I'm not sure exactly what. It would be a good idea to check your wiring diagram against your car. Ask here for specifics if you get stuck.

--DD