Yea, another electrical ?

[ian s]

1986 911 Cab
OK here we go. I've searched the posts and couldnt find what i needed.
No driver side rear running lights. just blows fuses.
for a while the license plate light was blinking with the left turn signal but now just no plate lights or L/R running???

At the fuse box if I disconnect the small guage gry/blk wire going out the bottom i have running lights everywhere but no driver rear running and license plate lights and the fuse no longer blows. I have looked everywhere and cant find a break, a short, nothing???
the blinking license plate lights threw me and after fooling around it stopped happening (I dont know what changed) I was convinced these issues were related but it stills blows the fuse every time that wire is connected even though they no longer blink with the left signal?
it still blows fuses even after I have done the following:
I have disconnected the harness at the taillight assy.
disconnected the gry/blk wire at the headlight switch
disconnected the license plate lights
i would chase it with a continuity tester if it didnt split off everywhere.
im generally pretty good at this stuff but im stumped!
Please help before I drive this thing off a cliff with myself in it!

Thanks: Ian:

[kidrock]

Ian, try bypassing the engine deck lid light. Sometimes the fixture gets old and crispy and will short out....the wires leading in and out of the fixture will get old and burnt as well. This particular issue will lead to the problem you've described. Just speaking from personal experience.

[ian s]

Thanks Kidrock. I went out to try the eng compart fix based on your and others advise. Nothin! I went so far as to take the harness all the way back to where it meets the right side tailight harness thinking there might be a break. Heres what I dont undersatnd. its the left side thats not working yet the engine comp. light is wired to the right side tailight harness? not to mention I have no power to it which i would expect being that the power wire for the left side runners is disconnected because it just blows the fuse.
here is another puzzler, when i use a test lamp I get a good ground from both wires leading to the eng comp. lamp? why would that be?

[ian s]

One more idea! could this be related to an interior light issue? I saw the schematic says to interior lights and ends. I did have a short issue years ago with the under dash rocker light?

[James Brown]

because the ground is flowing through the lamp, you have to check ground on one side of the switch, power should be on the other side of the switch. when closed, power on one side + ground on the other - the "resister" is the lamp = light

[E Sully]

[ian s]

Hi Thanks Ed, do you have the remainder or upper section of that schematic as well? I keep noticing discrepancies between wiring schematics on the forum. trying to find one for the 86 cab with all options. I notice the one you posted had a three pin connector to the tail light assy. mine has a five pin?
Mine is also a grey market euro car and i'm wondering if that accounts for some of the differences?

Thanks: Ian

[kodioneill]

Doe's this car have drivers side rear fog light?

[E Sully]

This does not show the reverse lights. Add the brown ground wire and it should add up. The reverse lights are on a separate diagram. These are Grn/Yel off the fuse 8, and Gry/Brn after the switch. The directional lights are also a separate fuse 7 feed.
The Gry/Blk wire goes directly from the fuse panel to the running lights of the left rear light housing where it changes to Gry/Rd in the housing. The license plate lights are separaetly fused and would be a totaly separate issue. From the diagram, fuse 5 feeds the left running lights and fuse 7 feeds the license plate lights. The one thing they have in common is the ground.


What confuses me is you wrote the fuse still blows with the Gry/Bk wire removed from the light switch, which would kill the power to the fuse that feeds the left running lights. No feed means no power to blow the fuse.

[ian s]

Thanks Ed. To be clear there are two wires leaving the bottom of the fuse. If I remove the small aug. one leaving the bottom the fuse does not blow.
This is the story of my life. Last night I took the harness apart all the way past the oil reservoir on the right side. The wiring in there was totally degraded and melted into the harnessing jacket from filter changes. Peeled all the wires apart there were basically melted together and wiped em down. It was late and I decided I would get to it today after work. I went and got a fuse-able link (tired of blowing the hard to find and expensive porsche type fuses) jumpered the new fuse and whala!!! no short! didnt even need the fuse link!
It looks to have been the deterioration of the jackets being bathed in oil and laying on the chassis. I think it was just coincidence that it happened to be a wire that is part of the harness wiring for the left side running.
Thanks a million for the help the schematic at least got me to right area.

Ian

[James Brown]

get some of this, works on german cars

[ian s]

NOW THATS FUNNY! as a past multiple triumph owner.
I have to tell ya guys, the Porsches have proven to be much worse and far more complicated electrically compared to my British cars.
although in all fairness the lucas stuff was total Capt. caveman from an engineering standpoint.

I equate it to the difference between an enfield and a luger, just cause it sexy don't make it better--- well?----with the exception of women----and at that, only english women---
no offense Fraulein

Thanks to all!
Cheers: Ian