turn signal/brake light short "77 911 s

[rainstory]

I have a short that happens when I turn on ignition and the fuse for brake lights and turn signals immediately smokes and shorts out. I have gone over all the grounds in the back of the car, and they check out- so do the contacts in the light fixtures. no problems there. I have now noticed the one small grey wire that extends from the turn signal group under the dash, becomes very hot at clip connection..Also, I noted that a brown (ground) wire becomes extremely hot at clip connection in the engine compartment that goes to the left turn/stop lights. Could it be that my turn signal switch is defective, or is it an ignition problem...HELP!!

[zedsn]

You have a + wire somewhere that is grounding out in my opinion. You are going to have to look over your wires and I would start with the rear lights/turnsignals and work your way forward. Maybe check the parking brake + connection between the seats while you are at it. This might take some time to sort out so be patient.

[timmy2]

The grey wire is your running lamp wire to the rear assembly. Also license plate light on that side.
You may have a wire shorting in the tail light harness, license plate lamp or the 6 pin connector assembly if all lamp bases and wiring are good.

[rainstory]

Thanks for the input. I am still tracking this down. I will look into parking brake tomorrow.. it makes sense that it may be there, because the fuse blows when ignition is turned on..fuse is ok when in off position. I will keep you posted when I get a handle on this problem, or scream for more input. Thanks again!

[wrxnofx]

To try and isolate, unplug one taillight and see if the fuse pops. If it does, unplug the other taillight and plug the other one back in. Or unplug both and see if the fuse pops. If it does then it's not the lights but the wiring to the lights that is shorting out.

[rainstory]

OK.. I found a main source of problem...grey wire extending from left rear 6 pole connector to tail light assembly was connected to brown /black stripe wire going into loom. Now..I have turn signals and brake lights. But.. I don't have turn signals when lights are on...brake lights ok with lights on. don't know what the grey wire from connector is for or where the brown with black should be connected,.

here a pics of wires in engine compartment

[ossiblue]

Isn't that brown/black wire the lead to the air flow sensor? If so, it would be a ground as soon as the ignition is turned on, causing the short. If the engine starts immediately, the ground goes away and wires don't heat up.

Does your fuel pump start running as soon as the ignition is turned ON?

The grey wire may be for the license plate light, but I don't have access to a '77 diagram.

[timmy2]

Pictures say it all... I will reserve comment on the state of your engine harness...

The brown/black on '76/'77 wiring harnesses is the air flow sensor wire.
It is supposed to be plugged into the plastic connector directly below it in your photo. It has the same wire colors (brown/black)

The grey wire is a hot taken off the running lights in the 6 pin connector normally used for the engine lid light option.

Plug the 2 same colored wires together in the plastic connector cover, and then tape up the exposed parts of the grey wire.

Connecting the grey to the brown/black of the engine harness was creating a dead short every time the air flow plate closed completely. (It closes to ground via a switch built into it.

[timmy2]

Here is a '77 current flow diagram for you.
https://www.dropbox.com/sh/jxno8o6qae3roun/AADW1qBcRc53LoEG0TPbRwFva?dl=0

And here are diagrams for a lot of common options:
https://www.dropbox.com/sh/hr6dquonkwjp23a/AABjbboPo-4J2L9nBoC5tbh6a?dl=0

[rainstory]

I want to thank all of you for contributing here to fix this problem.. I had been rear ended a few months ago, and the body shop removed the bumper and possibly the left rear light. THEY are the ones who put the wires back in the manner that they were causing the dead short. I would have never know if someone had not pulled alongside me one day and told me that my brake lights were out.

And.. yes my fuel pump pumps immediately with the ignition on, before starting.

[timmy2]

Follow my directions above and the Fuel Pump should stop doing that if the switch contacts haven't burnt up.

For your viewing pleasure.

Building SC and Mid Year Engine Harnesses

[rainstory]

Thanks Dennis.

Re hooked up as you indicated and have blinkers, and fuel pump is working properly now.

**NEVER TRUST A BODY SHOP TO RESPECT YOUR PORSCHE**

[timmy2]

Good advice on the body shop.