Quadcammer

Howdy all,
trying to get my wiring harness down to something manageable. i've found my 99 is a bit different from some of the other posts I've seen and i want to make sure I'm not screwing the pooch.

Questions:

1. My 99 never had anything going into terminal 12 on the blue immobilizer plug. I've retained the following:

II/1, Brown ground (the big brown wire that bolts beside the box)

Blue
I/2 Orange/Black, Diagnosis (the OBD plug)
I/3 Black/Red, Signal transformer box (nearsteering column)
I/4 Black Signal transformer box
I/14 Gray/Pink Speed Signal
I/16 Orange , Fuse E1 (fuse box)
I/23 Orange/White, ECU term 88 "w" lead - diagnosis
I/36 Black/Brown, Fuse B6 (fuse box)

For the black immobilizer plug, I've also retained the following wires. Would like to know if I can remove them?

Turn Signals: Black/White
Turn Signals: Black/green
Door Contact: Brown/Green/White
Extrnl Consumer Terminal 30: Red/Brown
Consumer Switched off: Red/Black
Red/Green: Terminal 30 and horn

I'm assuming these things can go.

2. Wires to relay for terminal XE. What do these go to and can I ditch it?

3. Did you all ditch any wires going to the power distribution unit on the firewall?

I'm sure I'll have more, but will start here.

Thanks all, really appreciate it.

C4 Pazzo

Regarding #3, yes, tons. Follow these steps:
1. First, disconnect the positive lead from the battery
2. Identify unneeded wires connected to removed components (e.g., door locks, windows, A/C compressor, spoiler, soft top, etc). Remove them back to the fuse block.
3. For any fuse no longer connected to any component wires, remove the wire between the fuse block and the power distribution block (there will be lots if you were aggressive in removing unnecessary components.

That should get rid of a bunch of heavy wire.

mjj0000

Quadcammer,

I have done this exact weight reduction project several times. I would caution you that messing up the immobilizer is to be avoided at all costs. I highly recommend that you disconnect the starter solenoid, wire in a test light in its place, and test the immobilizer periodically to make sure the engine will start. If you wait until the end you might find that the problem is only solvable by pulling out your wallet.

I recommend that you identify and keep some of the fused power circuits. There is a host of track car specific items that will need to be powered. You can't do better that to reuse some of the fantastic Porsche engineering.

Finally, I recommend that you search on my user name. I have commented on many similar threads. It would be a lot of work to replicate all that advice here, but it's all still buried in there.

Cheers,

Michael

Quadcammer

Thanks Michael, thats good advice. I spent quite a bit of time with the wiring diagrams before I started this, so I'm reasonably comfortable with whats been done thus far. The slight differences between 1997-1998 and 1999 make it a bit tricky. Will do some searching. As to your point about power, I've left a few power wires ready to go. That said, I'm actually keeping two cigar lighters to power my solo and garmin video. Hence I will be keeping my XE terminal, which is a relay that includes the cigar lighter.

BillC3

A few more questions on wire thinning:

I'm in the process of thinning my wiring harness, and there are several large cast-rubber "grommets" where wires pass to/from the front of the car. There are a number of wires I'd like to remove (those to/from the amplifier, the windshield washer, etc).

How do y'all handle the wires in those rubber castings? Slice open the rubber to pull the wires out? Clip the wires off at the ends of each casting and just leave the short pieces inside the rubber? Just leave the wires alone? I have tried pulling the wires out, but they are too well-adhered to come out without breaking.

Thanks!

Nickshu

I cut open the grommet in the frunk area to remove the unwanted wires. This is tedious and the grommet is adhered to the wires throughout. It's a pain. In retrospect I would have just cut them off against the grommet and left it like that.

Quadcammer

This is what I did as I saw ahead of time that the wires were adhered in there. Just chop them as close to the rubber as you can on both sides and move on.

mjj0000

Once the wire has been identified as extraneous, I cut it off close to the grommet and continue.

mjj0000

Once the wire has been identified as extraneous, I cut it off close to the grommet and continue.

Quadcammer

well I decided to be a bit conservative and leave most of the wires i had left. starts, runs, all good, so no harm no foul.

tgsmith4845

I’ve got a wiring harness from a ‘97 parts car that I’m going to thin out for an SPB. Does anyone know where I can get a full size wiring schematic on one page? I’ve got the manual and can piece all those pages together if necessary but thought I’d see if I can find one complete schematic first.