I know that no one has heard of this issue.

[deoxford]

Ok This is a new one for me I am sure that will be new to most of ya'll as well.(911T 1972)

1. My headlights stopped working, all the rest of the lights will come on but no headlights. And when the lights are on the brake lights stay on as well.

2. The brakes do work with the light switch in the off spot.

3. When the brake lights work, they also turn on the front turn signals.

4. Now this is the good one. When the lights are in the parked spot, and you hit the brakes the fuel pump comes on.

I have read about #1 before and most say it is the stalk

But # 4 is new to me

I am looking @ the wiring diagram , I not sure where to start

Please help if you can

Thanks
Derek

[deoxford]

Anybody?

[1980 911 sc]

check your ground wires, all of em. then recheck them.

[theiceman]

or have an exorcism :-)

[afterburn 549]

Hmm like said, it is a ground problem..simple ans but a lil complicated. You need to chack and see "if" you have everything grounded, and un bolt and shine things up a little.

[Zeke]

Still, how is he backfeeding his fuel pump?

[theiceman]

Theres a short somewhere. when he presses the brakes the power from the brake lights is feeding the fuel pump. a couple of wires have probably rubbed together somewhere.

[afterburn 549]

Now for some gibberish , I will repeat what I have been told by some high sounding engimneers. Loosely quoted - "the Brits are the only peo. with proper car wiring ( not counting Lucas Prince of Darkness ) because they use a "Neg. grd. sys." Battery voltage actually comes from the Neg. side and flows opposite to what everyone thinks. Grd. straps are greatly neglected and thought to be unimportant."
Now what happens the electric forces will take the least path of resistance and travel in any direction that is ezr then what we would want then to do even if it were to back feed and create parallel circuits by using an other grounds some where...guess I did not ans. the Q. but that the suposed of it all.

[deoxford]

Ok, so I should start all the grounds first

[afterburn 549]

that would be my 1st idea. then pull all your fuses and start one by one to connect them...might pt you in the right circuit direction when some thing happens that should not.

[wahoofan]

Derek,

Believe it or not, I experienced almost the same problem twenty years ago on my '77 320is! Car started doing funky things, like horn beeping when turn signals were on and wipers going when I hit the brakes. Within about ten minutes it just died - no fuel delivery at all. I had it towed to my mechanic at the time and he fixed it for cheap(IIRC) in about a day. Turned out that the fuse panel was mounted on top of a front fender and had a big clear plastic cover over it. Somehow, the cover had been cracked and water splashed up in there and shorted out some fuses. Once he dried it all out and re-connected a bunch of fried wires it was good as new!

Hope this helps.

[juanbenae]

april foo's in july?

[450knotOffice]

Automotive electricians blow me away. How they find these odd short circuits is beyond me. I had a car 20 years ago that suddenly developed a huge short and kept blowing the fusible link within seconds of turning the ignition on. It was maddening. I finally gave up and had the car towed to an automotive electrician. The guy had it figured out in short order.

It turns out that when a buddy of mine had rebuilt the carburetor he had installed the choke backwards (it was an electrically controlled choke)which grounded it to the carb body and hence the engine block. HUGE short. Easy fix. Re-install the choke properly.

I'll never forget that. How he figured that out so fast is beyond me.

[Wayne 962]

Definitely a short circuit. I would start with the fuse panel first - the most likely area for problems. It may be obvious after about five minutes of looking for frayed wires...

-Wayne

[Grady Clay]

Derek,

That’s a good one. I’ll look at the diagrams this morning. I speculate a ground.

Best,
Grady

[jester911]

Sounds like someone transplanted an old Lucas electrical system in your car

[911mot]

WRONG BULBS IN THE TAIL LIGHTS!!!

[theiceman]

Contrary to popular belief electrical shorts are easy to find if you have good sound troubleshooting skills and a multimeter. If you have these you will be fine. If you are shooting in the dark it could be a long day. Definitely start with the grounds although they will be fine. The fuse box is a great start. In fact I would disconnect the battery. and comnect an ohm meter between the brake lights and the fuel pump. when you press the pedlde it will go to 0 ohms if you have a short. There you go your first T/S step. Leave the meter connected until you find what is touching , once you do it will jum to infinity ..and solve a few of your other problems too I guess.

[defcon65]

Check all the connections in the fuse block and then all the ground connections. Isolate the circuits one by one and check components from one end to another. Look for damaged insulation on wires that may be contacting the body and grounding out. Wayne's 101 book explains this more fully than I am able to. In short, it is a long process of elimination with the hope you will happen upon the real problem somewhere in the middle. Electrical problems can have very weird symptoms but often are caused by very basic faults. Always approach this kind of troubleshooting with the 'Simple Solutions First' mindset. Hopefully you will uncover the problem before you have to start pulling out wiring and replacing it. On a car that age, corrosion and hardening of the copper wires, insulation becoming dried and brittle and vibration working connections loose can all be suspect.

[afterburn 549]

I am still thinkin some one omited a GRD somewhere