gf261

I was driving my 89' at normal highway speed, 65-70 mph. Smoke began to seep out from under the passenger footwell and the engine lost power, so I shifted to neutral, shut it off and coasted to the shoulder. I had the car towed home so I could explore the problem. Obviously electrical due to the smell, I removed the floorboard electrical panel and flipped it forward. One of the wire looms that runs from one of the 14 or so pin terminals along the bottom had shorted. The corresponding wires on the back of the panel had shorted two other wires with the sheathing being burned through. I traced the culprit wires through the firewall, finding that they run over the passenger side fender, down between the fender and cooling fans, where I think they terminate at the cooling fan. Any suggestions on finding a replacement harness, and/or causation? The damage seems to be confined just to that one harness.
Thanks in advance for any insight.

Lizard928

I will warn you now that harness is a real bear to have to try and replace with the engine in the car.

so good luck with it.

Alan

Did the fuseholders melt for the fans?

Alan

gf261

They didn't actually melt Alan. This is a generic photo that I had, but I believe that it is the same position that mine melted at. It didn't seem to damage the terminal plug itself, just the wires behind the fuse panel. Inside the wiring harness itself, it was obvious how hot it had gotten since it bubbled the rubber sheathing that the entire bundle of wires was in.

gf261

Okay. Further investigation has found the cause. The upper radiator hose was resting on the wires running to one terminal of the passenger side ignition coil. Once it rubbed through, the wires grounded against the metal rim of the coil causing the short. (pic 068 and 065) This fried the top right-wire as viewed as it would be plugged into the bottom portion of the fuse panel in position "Q". (pic 070 and 071) I am in the process of stripping away all of the sheathing to see if it damaged any wires other than itself, but so far they look okay. There is a thick (10 or 12 ga.) wire that runs to a plug in the second picture. On the male side of the same plug, the top wire is exposed and the sheathing on it dry-rotted to the point that you can roll it between your fingers and it powders up. (pic 064) This wire runs in front of the block along with several others, and I believe to the ignition coil on the driver's side, but patience and light were failing me. I am guessing that the ones running downward go to the cooling fans? (pic 063)Any and all suggestions are welcome.

SharkSkin

I suggest that you not connect that wire to your left nut -- could be painful.

SwayBar

I do not think there is a reason to replace the entire wiring harness; just run/replace new wires for the affected ones.

gf261

I must be a glutton for it Dave, the other is labeled for the right one! Tell you what though, if doing so would get my baby running again, I'd gladly make the sacrifice. I am planning on just replacing the burnt wires, it's just that the problem child made such a mess when it went. Any suggestions on how to get to the portion of the looms between the firewall and where they emerge into the engine compartment area?

Lizard928

I have pulled these harnesses out of cars, and put them back in. I dont see how replacing these one or two wires with the engine in the car is feasible.

But you could solder a new wire and do alittle wrapping with electrical tape adn try to pull a new wire through.

Alan

Hah! you had me confused there - your earlier picture is of a pre- 85 panel that you don't actually have right?

Pulling any wires through that boot (without damaging things) is virtually impossible on a GTS - I'm sure its much the same on any S4. Pulling them through the full loom sheath...even less feasible..

Routing some new wires may be possible but you need a new way through... there is a grommet under the pod - that feeds through the the bulkhead area behind the wiper motor - its not packed - but its not very big either. Much easier to use than the CE loom though - longer though...

There are some other options you can consider... Feed the fans supplies direct from the starter connection via local fuses (don't use the jump post for this). Test the loom to see whats shorted to what... there is still some risk in this over time... maybe there is enough still good & usable that you only need to eliminate a few connections and route those seperately...

Some of you have heard me talk before about the lack of correct fusing on the feeders for the Cooling Fans, ABS, ECU's... they come direct from the battery - this is the result... no protection = melted wires....

Alan

Kevin in Atlanta

This might be a good time to suggest improvements that might help others avoid this nightmare.

Alan

Well the best bet is to fuse them at the battery (I have done this). Skinny little lines with no fuses from the battery is a horrible idea - but Porsche does it extensively... All these should have a fuse as close to the battery as possible.

Also the whole CE panel should be fused (but isnt) - not so easy to do - I am working on this part still.

Alan

gf261

Alan I think that I will take the under pod route. As aggravating as it will be to replace all the wires in that entire plug, I just don't want to take the chance of there being a little scarred place somewhere along the line that will become a problem later on. My main concern is getting the harness sheathing opened up as far down as I can to see if it burned anything by running next to another loom.

Alan

BTW - to the left Nut Right / Nut thing... don't worry about it they both connect together on the panel (and at the other end at the jump post) - with the panel out this is quite obvious... so just bolt them back on the top however you feel like...

Garrett - good luck - lots of work! I would consider not doing this on the fan supplies (wire direct to alternator or starter via local fuses). I think Porsche's approach here is quite odd - to me its much better not to run these throughout the car. But don't use the jump post because it will add noise/voltage drop to the CE panel (the jump post wiring is really just too small). These are the heaviest duty wires and better if they aren't any longer than needed - they will also be the hardest to route through that grommet (and around the pedal hardware etc - its busy up there...

Alan