shyamvenky

i noticed (after a few months probably) that my brake lights were not working at all (1986 3.2 carrera). Lights seemed ok, nothing wrong with the brake switch i suppose.

i opened up the fusebox to find that the leads that were supposed to go into fuse#7 (brake lights and cruise control) were missing. looks like they were snapped somehow (probably when i installed HID lights back in spring). the fuse looked good, but i replaced it anyways.

i am pretty sure that this is the reason why the lamps aren't working, and the cruise control as well (which i hardly use, but i did notice that it wasn't working a month ago)

where would i find the wiring that i can extend/attach to the fuse? this would require removal of the fusebox. would some wires have to be removed/cut in the process as well? i don't want a no-start car, at least it works now. the job seems straight-forward. do you think i might need to send the car over to powertech for this? (and if i send it over, i am planning to get a shortshifter kit installed too)

thanks
shyam

1986 Targa

Here's the CKT diagram.

shyamvenky

wow! that was quick. thanks a lot for the ckt diagram. there are no wires going into the fuse in the box. and thats the culprit behind my brake lights and cruise control not working. was just wondering where these lines come from (physically that is) are they through a harness or is it an independent wire?

i think i'll need a 10mm offset wrench to remove the fusebox. (10mm spanner seemed to fit fine, but i wasn't able to remove the bolt) i will need to disconnect the battery before meddling with any of the wiring.. correct? (removing the ground clamp from the battery should do it i suppose, or are there any other standard procedures?) please pardon my ignorance as i haven't meddled with the wiring a lot. i didn't have the need to do it when i was installing the HID lamps.

--shyam

Brett San Diego

Something doesn't compute. The wiring diagram says fuse #4 is the brake lamp circuit fuse, yet you say that fuse 7 is for brake lamps. You say the wires possibly "snapped," but if they broke away from the connection at the fuse, then the wires should still be sitting there. No? What makes you think the wires disappeared after becoming disconnected.

FWIW, brake light switch failure is common. And clean the contacts in the fuse box just to be sure.

Brett

shyamvenky

thanks for your response Brett.

As per the listing on my fusebox cover, its fuse#7 for the brake light and cruise control. Yes, you are right in that the wires must be lying around somewhere in there, possibly behind the fusebox or down below. I wanted to know if there's an easy way to identify the wire based on where it comes from (harness, location, colour etc) as I don't know what other connections might be snapped (bypassing the fuse) in there.

I did read quite a bit about the brake light switch failure here in the forum, but the lack of wires seems more likely to be the cause. There is a wire from the bottom end of the fuse, but no wire is going into the top. In any case, I don't want connections to bypass the fuse. If fixing this doesn't work, then its possible that the culprit could be the brake light switch.

--shyam

1986 Targa

Here's a little more help from my "Well Loved" factory manual.

As you can see fuse #4 on fuse block #2 is actually fuse #7 when all of the fuses are counted from left to right.

Also, the wiring color codes, the 4mm RT/GE is the feed for the fuse strap X,
which also services your mirror switch, and other functions.

If those items work, then, you have the 12V to the fuse.

You should be looking for the GN/BL and SW wires which are designated for the brake lights/cruise control.

If reconnecting the wire does not resolve your issue(s), then it is very likely the brake light switches.

Good luck,

Gerry

1986 Targa

Here's a picture of our '86 fuse panel.

Because we do not have CC, note the absence of the black wire at the bottom of the fuse.

Also, check my post on Pelican- "Added fuses and Relay".

For the 84-86 3.2 M/Y, the fusing was not Porsche's "finest hour".

Best,

Gerry

Brett San Diego

I was just going to say that some fuses are connected to neighbors by "bars" in the fuse box with one wire emanating from only one connection to a group of fuses. That looks to be the case with this fuse.

Nice help, Gerry.

Shyam, you can pull the connector on one of the brake light switches and check each pole for 12 V to ground (ignition on). One of them will be the power feed and will have 12 V. If not, there is a problem upstream of the brake lamp switch. Then you could jump the poles of the connector, and that should light the lights. If they do light, then there is no problem with the lights, and the problem is the switch.

Brett

1986 Targa

Thanks,

Also, the wires located on top of the fuses, which are not feed wires for the straps, are fused at the location of usage.

Fog light, P/W ect....

Best,

Gerry.

shyamvenky

I checked the thread this morning only. I was meddling around with fusebox yesterday late evening. I was just about to ask for a picture of a fusebox, and before I could eve do so, you have them posted

I am attaching pics of my fusebox. I'll compare em both, which should tell me if something's wrong with mine. As far as the quick inspection went on my fusebox, it never seemed as if something was connected to the top of fuse#4 (on panel 2). There is the BLUE/GREEN wire from the bottom. I did not see any free-hanging wire behind the fuse panels.

Also if you'd notice, there is a thick RED/WHITE connector lying free on the bottom-left. Wonder where that's supposed to go. There was another wire that came with a 1A glass-fuse (in the plastic capsule) that was lying freely. This wire came with a pair-wire that joined to a location on the body (through a bolt below the washer-fluid tank. A couple of other wires were joined here too (should be a grounding location, right?) The pair of wires seemed to come from the dash (right-top corner under the luggage compartment, not coiled/grouped with other wires)

I will look into the brake switches this evening. But if the issue is with the switches, then what about the cruise control? Both of them failing together was what led me to suspect the fuse-wiring.

Brett San Diego

Just to be sure, remove the fuse and clean the contacts on the fuse and the fuse box. Take some sand paper to the metal ends of the fuse and the metal clips that the fuse plugs into. Make sure you've got good electrical connections to start with, then begin further diagnostics. You need a volt meter.

Brett

shyamvenky

I had a closer look at the ckt diagram from Gerry's Pelican post "Added fuses & relays".
So if the brake switches fail, that disconnects the cruise control regulator also.. right?
If that is so, then it explains why the CC is also not working. Please correct me if I am wrong.
I'll jump the switches and test the lights this evening.

Vincent C.

check the switches on the master cylinder.....vinnie

1986 Targa

Here's a few ideas:

1986 Targa

According to the factory fuse block diagram, (see my previous post), there should be two wires at the bottom of fuse #4.

However, the CKT schematic only shows one?

If this is an error, It's first one I have found in this manual.

Now, the Bentley, that's another story.............