Help: Electrtician needed

[adam911]

Was just out cruising in my 69 911E. All of a sudden plumes of smoke came into the car and it lost power. I pulled over rather quickly and killed the ignition. I then determined the fuel pump was no longer working. Got the car home ($250 tow) and set to investigating. Checked the wiring to the pump and found no power. Took the pump off and tested and it's working. I then checked the wiring to the pump and have continuity. I then started tracing via the wiring diagram. Fuel pump is poll number 6 on fuse box number 1. It is located on the left side (in the diagram) along with 2 red wires one which goes to the rear fusebox and the starter via terminal connector 62. The second red wire goes to the ignition switch. The other side of the fuse on terminal 6 has 3 wires, one red wire which goes to "emergency blinkers" which I believe to be the emergency blinker switch. A black with yellow wire which goes to the stoplight switch. The third wire is grey with brown, which goes to the backup light switch. Interestingly the emergency blinkers are only currently working with the ignition on and I believe they should work with the ignition off. Also neither the backup lights are working (they always seemed to work intermittently). And the stop lights are not working either. I then had a look at the loom and where the majority of the wires are bundled together just below the fuel tank neck I notice some burning, stripped the tape off and see that the red wire which is the emergency blinker wire is burnt and also the casing looks melted where it joins into the fusebox. I'm just about to jack the car up and check continuity to the fusebox and same with the stoplight switch, but thought I would post here to get some pointers first.

Any help would be most appreciated.

Adam

[E Sully]

I have found that loose or corroded terminations, switches with worn contacts, and bad grounds will cause overheating of wires. A continuity tester will not neccesarily show this. The continuity tester operates with a lot less amperage than the circuit will draw under full load.

[adam911]

Well, I wasn't actually using a continuity tester, but an ohm meter, but I guess your point stands either way ED.

I've done some more fault finding and here's what I've found....

One of the wires on the brake light switch had come off and was badly melted, which made me think it had shorted to ground and that was the smoke inside the car. I stripped it back some and fitted new connectors. With my ohm meter set to 2000 I have a reading of 003 between both wires and the pole on the fuse box. I would have thought I'd only get continuity on one wire though, as the other goes to the brake lights. That's a bit confusing! Also, the brake lights still don't work. I turn my attention to the back up light switch, I get a reading of 001 ohm on one wire and 007 on the other between the wires and pole 6 on the fuse box. Again confusing as one of these should be going to the backup lights and I wouldn't expect continuity on that wire. These don't work either. So I turn my attention to the emergency blinker switch. Pop it out and it has attached all the wires from the diagram except for red wire number 15, which should go to pole 6 on the fuse box and red wire 49, which should go to the blinker flasher (labeled 34 on the wiring diagram). Now the really odd thing is this all worked fine before my problem today. I checked up behind the dash and they're not there.

I came to the conclusion I've missed something fundamental and not checked for voltage at pole 6 on the fuse box. I turn the ignition on and I get no voltage reading either side of pole 6, 7 or 8. However I do have voltage at poles 1 through 5. So I checked the fuses in the engine bay and they're fine. But, I now realize why the backup lights and brake lights don't work also.

So what am I missing here? As you've no doubt realized my understanding of electrics is fairly rudimentary, but I think I've worked through this in a fairly logical manner.

I should also add that I have good continuity between the melted red wire in the loom by the gas tank neck and pole 6 on the fuse box, which suggests to me they are the same wire (this is the wire I was expecting to find attached to the emergency blinker switch).

Any thoughts?

Adam

[adam911]

I just thought of something else. The black and red wire on pole 30 of the emergency blinker switch goes to pole 5 of the fuse box. Pole 5 is live even with the ignition off, yet the emergency blinker lights don't work with the ignition off, only with it on (currently). This would make me think the emergency blinker switch was faulty and that was the root of my problem if it wasn't for the fact neither red wire 15 or red wire 49 were present.

So, at this point I can only assume that the red wire that has melted in the loom by the filler neck, that according to the diagram should go to pole 15 on the emergency blinker switch is what is supposed to be supplying power. But where does it go?

[adam911]

Just been studying the wiring diagram some more. I see that on pole 6 of fuse box 1, on the left hand side I have my wire to the fuel pump and 2 red wires. The one red wire goes to the rear fuse box and the second red wire goes to a 6 pole "terminal connector" (labeled 65 on the diagram). A wire then loops over 3 poles and a red wire runs from there to the ignition switch (coincidentally labeled pole 15 on the ignition switch, the same number as the missing wire from the emergency blinker switch). So, I'm thinking the red wire from pole six which has melted in the loom below the filler neck is the wire that runs to terminal connector 65. So my next question is: does anyone know where terminal connector 65 is located, as it's very hard to trace due to it being bound up in the wiring loom?

Any help appreciated.

Adam

[adam911]

Bump

[adam911]

Bump

[E Sully]

I don't have a wiring diagram for your year, but now that I am home from work I will see what I can find.

[adam911]

Thanks Ed,

I've actually got it sorted. I took the ignition switch out and couldn't get continuity between the red wire on pole 15 of the ignition switch and the red wire that goes to pole 6 of the fusebox, so I ran a new wire and taped it to the loom. Everything seems to be working, though I am mindful of the fact that I've now circumvented the terminal connector labeled 65 on the wiring diagram.
I have the correct wiring diagram in PDF format that I could email to you if you want to take a look.

Adam

[donporfi]

Adam
Also while you are at it, clean the terminals where the fuses rest at the fuse panel. I had a problem, blowing the fuel pump fuse. I solved it by cleaning the the fuse panel. I used a mototool with a small wire brush, that solved the problem.

[adam911]

Yes I gave the whole fuse-box a good clean, terminals etc....fiddly job