rgs944

After reading Jim's post again he does refer to a small brown wire but I am not sure if he referring to the one that goes down towards the starter or back towards the fan at the 14 pin.

OK, maybe I figured it out. The wire I am refering to looks to go right to the ground point by headlight. I did tug on it a little and saw it move at the other end. At least now I think I have an end damage point going that direction. It is strange how that wire could have got burned bare but did not really effect the other wires in that loom section.

rgs944

Like in the great movie "Ferris Buelers Day Off". Anyone, Anyone,. I'll even take some moral support right now. I have to say i am feeling a little more positive as I go along though.

WallyP

Perhaps this will help...

https://rennlist.com/forums/928-foru...-out-list.html

Bill Ball

If you mean the large harness that goes from the 14 pin connector down across the front of the motor to the starter and alternator, yes, it can be done engine in. Well, sorta. There is one clamp on the top of the crossmember, and I don't know if it can be reached without dropping the crossmember (or alternatively loosening the motor mounts and lifting the motor a bit.). So, yes, technically engine in, but...

And Carl sells the engine harness. I have installed one of his harnesses (with the crossmember out). Very nicely made.

http://www.928motorsports.com/parts/wiringharness.php

But from your description of where the brown wire goes your issue may be elsewhere in one of the other harness sections.

To supplements the link Wally provided, here is the pin-out I came up with for various S3 and S4 model years.

87-88 are the same. 89+ has an additional wire (pin 7)

TOP (male pins)
PIN - WIRE COLOR/STRIPE - Function
1 - Blue - alternator exciter
2 - Blue/Black - oil pressure
3 - Blue/Yellow - coolant temp
4 - Blue/White - oil pressure
5 - Blue/Green - coolant temp
6 - Green/Blue - oil level
7 - EMPTY except 89+ Brown/Red - oil pressure
8 - EMPTY
9 - Black - AC compressor clutch coil
10 - Green - intake air temp switch for fans
11 - EMPTY
12 - EMPTY
13 - Brown - intake air temp switch for fans (ground)
14 - Yellow - starter solenoid

The BOTTOM (female pins) differs at:
7 - 89+ Brown/Green
10 - Brown/Blue

The 85/86 connector differs in:
7 - Red/White - auxiliary air valve
10 - EMPTY (in 12 instead)
12 - Green - intake air temp switch for auxiliary fan
13 - Red/Green - intake air temp switch for auxiliary fan
and top and bottom wire colors are the same.

victor25

Sorry to hear about your fried wires. I will be watching to see if it was actually the starter or something else that caused the meltdown. Sure seams like that would be it though. You will have to be sure to fix the problem before the wires though, I'd hate to see a total melt down or worse

GregBBRD

Yes, simple.

GregBBRD

Interesting approach.

You have a known starter problem and you screw around with it until the loom to it melts.....and that is the insurance company's responsibility.

I never can figure out why my insurance rates are so high......

rgs944

Greg I did not say it was anyones fault. I don't think insurance is just for fault. I guess you could use the same thinking if someone drives in the rain or snow and slides in the ditch. The insurance company should not pay them because they should have been smart enough to stay home in the first place. Plenty of people have tapped on starters before without shorting them out. We don't even know if that caused it in the first place. Maybe Porsche should be blamed for making a bad electrical system. The Germans do a lot of good things but electrical is clearly the weak point. Consumer reports have always ranked German cars very low for electrical problems. Sorry I have to ask for help and then get the third degree and blame from someone. Never hurts to kick a guy when he's down.

rgs944

Now back to the main problem. I did see Carl's engine harness but I do not think I have any damage in that loom. The damage is from the fuse block to the 14 pin. The rest of the damage is from the 14 pin going to the ground point by the head light. This week I will get the fuse panel out, starter out, and open the loom going to the fan area. That should give me a complete assesment of all damage.

j.kenzie@sbcglobal.net

I kind of doubt mechanical or electrical failure will be covered by your comprehensive auto insurance. It wouldn't matter the reason for the failure, I think. If you came out in the morning and it was burned to the ground, the insurance company would try to blame electrical failure to deny your claim. If they would cover it, I certainly agree that it should not matter if it is your fault or someone else's, except for future rate calculations.
Good luck with your problem, I hope when you pull the central panel, you will see something helpful. My understanding is the main power of the car goes from battery > starter > alternator > jump post > fuse panel. I am not sure at what point the 14 pin connector fit in that chain.
Dave

jcorenman

Rob, the brown wire I was referring to was on pin 13, which goes to the intake air temp sensor, part of the fan control. That's the only brown wire that I found on the engine (male/top) side connector of the 14-pin connector, that agrees with Bill's list.

But your more recent post said that the engine harness is OK, that the damage was on the lower (female) side of the 14-pin connector, right? The wire on pin-13 is brown on that side also, and goes to MP-II to provide a ground to the intake air-temp sensor. MP-II is on the engine-compartment sidewall, passenger's side, near where the headlight shaft goes through.

If that's the toasted wire, then it got tangled up with battery voltage, somewhere. If there is a short between a large wire connected to battery, and a small wire connected to ground, then the large wire is not going to be damaged. That is the nature of electricity, the little guy loses.

Now, here is where it gets interesting: If you look at the wiring diagram for an '87, page 5, zone K-38 (I'll wait, you need the wiring diagram to follow this), you see a section of the 14-pin connector (called T18, but it doesn't show that here). The wire to the "Thermoswitch Intake Pipe" is brown, 1.5mm. The wire on the other side, to MP-II, is also brown, but 0.5mm. It's only a sensor return, it doesn't need to be large.

But remember the "little guy loses" analogy... If you have a short from some large 12v wire to a small ground wire, to an even-smaller ground wire, who winds up getting toasted??

So what I think happened is that there is a short somewhere in the engine harness, between the yellow starter wire and the brown intake air-temp sensor ground wire. It didn't burn there, because there was an even-smaller wire on the other side of the 14-pin connector. So I would trace every inch of that harness, from the 14-pin across the front of the engine, through the driver-side cam-belt cover, over the lower crossbar to the alternator and starter. I am not sure where the intake air-temp sensor peals off of that, I think it is near the alternator and oil-pressure sensor.

I wouldn't be too hard on Porsche electrics. The basic design goes back to the mid-70's, and your '87 (and our '88) were done in the mid-late 80's. Having dug into some much more modern cars, I am not sure I would trade. Any time you have a short, something bad is going to happen. Sure, big fuses on the high-current loads is good practice, but I don't think that is the issue here-- somehow a high-current 12v wire got crossed with a small sensor-ground.

If you can, please post some pictures-- that will help a lot, I think.

Alan

I think you need to stop looking and guessing and start measuring.

If the section of interest is the 14 pin connector to the CE panel - disconnect both ends and start testing for:

1) Connectivity end to end on the connectors that are suppose to be connected

2) Non conductivity between connections that are supposed to be isolated

To do any thing else (short of complete replacement) just risks a complete issue repeat after you are completed with repairs -> pointless!

Similarly repairing this section without certainly to the cause risks an issue remaining elsewhere giving you a complete repeat - so you need to either:

A: Determine the exact cause from the symptoms and ensure its fixed

B: Evaluate connectivity & functionality down & up stream from whatever is damaged

Sorry - but for me visual inspection is a quite insufficient approach here.

Alan

GregBBRD

I'm just really sensitive about this particular subject.

I have customers that come in and want me to overbill insurance companies on a job, so they can satisfy their deductible.

I have to stop and ask them what the difference is between me screwing their insurance company or screwing them.....either one is immoral, in my mind.

I live my life "straight up and down". No one gets screwed.....ever.

Mrmerlin

funny how these words seem to catch up to each and every one of us

from my quote from another thread post 16 ( link below)

"Both of these fine gentlemen operate with integrity.

We are very fortunate to have them here sharing their talents with us,
For they are both excellent at their trades,
and they really do care that they do a great job!

Keep Em Flyin ! "


https://rennlist.com/forums/928-foru...ger-tyson.html

rgs944

Yes, I am kind of just guessing right now and that is why I am going through some different scenarios and options. I just have not had time to get in there and get good pics and further assesment. I will do more this week and get some good pics. I am sure there is a process to get it back in shape and I thank everyone who is helping. Greg, Stan, Allan, Jim, and I know I am leaving a few out.