New wiring harness. Ignition wiring help!

Mr.Puff · 02-23-2009, 10:08 PM

Alright, I have another wiring question. My new wiring harness has the following circuits:

Alt power.
Alt exciter.
Solenoid power.
Choke power.
Coil pos.

Then two ignition connectors with a bunch of spaces for attaching wires. All of the wires except "Ignition switch start" go to the fuse box. Ignition switch start is a free wire that leaves the connectors:

Ignition switch acc.
Ignition switch coil.
Ignition switch ign.
Ignition switch power.
Ignition switch start.

Here is a picture of the DME wiring bundle.

I figure that numbers 1 and 4 go to the coil pos. Number 6 I assume is fused and then connected to the fuel pump circuit. That means I will have a Y with the bottom going to the fuel pump and the top 2 going to the fuse box and number 6. The only wires I have free from this bundle are numbers 1, 3, 4, and 7. Then I have a giant black wire that goes to the positive on the battery, and another medium yellow from the main harness in the tunnel that I believe goes to the alternator.

The yellow wire is in this picture. I am referring to the yellow wire on the bottom right of the bundle.

(It is probably a no-brainer that the choke power is not used, but I included it in my list just in case.)

Mr.Puff · 02-24-2009, 05:23 PM

:P Bump.

rick-l · 02-24-2009, 07:25 PM

I have no idea what you are asking but I can tell you what 1-8 in your picture want to see.

The DME relay pin 86 wants to see 12 volts in Ignition switch pos run or start
12 v into DME pin 29 tells the DME the AC compressor is running
DME 4 is an input that runs the fuel pump when the key is in the start position
Same as 1 through the fuse
injector pulse width to CASIS
DME relay pin 87b runs the fuel pump and OXS heater (also yellow)
Goes directly to the battery
spark timing to tach

Where's the wires to the coil and injectors?

Mr.Puff · 03:44 AM

OK. I have a picture to help explain. I have purchased a pre-made fuse box with these circuits that I have identified as belonging to the engine or ignition switch.

The wires from the DME harness that I have to connect consist of 1, 3, 4, 6, and 7. Then I have the fuel pump power wire and a large yellow wire that I believe goes to the (Edit: I kept saying alternator when I meant starter). The ignition is completely disconnected at this point. The connectors are to plug the ignition back in.

The circuits are supposed to go directly to the corresponding components. I have complicated the matter by leaving the engine management system intact. Now I have to recognize the wires from the existing harness and plug them into the circuits from that new box. The fuel pump will plug in like pictured (maybe).

gsmith660 · 02-25-2009, 02:43 AM

You are using a non porsche wire harness or a non porsche fuse box?

Mr.Puff · 03:42 AM

Correct, it is a generic fuse box/harness with 21 circuits (including 2 headlight connectors). The headlights, turn signals, hazards, power windows, radio, gauges, etc... should be fine with the provided circuits. For those it is more of a signal wire (switch), ground, and power. The engine management system has me nervous.

I think 1 and 3 go right back onto the ignition switch where they were removed. 4 goes to the coil pos. circuit, which I assume is connected in some way to the ignition switch coil wire on the ignition connector. 6 is attached like I have described in my picture. 7 goes to the battery. That big yellow wire from the main tunnel harness actually belongs to the starter. It goes directly to the ignition, probably on the ignition switch start wire then to the ignition (50). Are these assumptions correct?

What do I do with solenoid power? It looks like the alternator is all taken care of in back, so the alternator wires aren't used. I don't have a choke (I'm pretty sure). So I will be using elec. fuel pump and coil start. Maybe "acc." stands for accessory. I do have a radio ignition circuit. Perhaps I connect the ignition acc wire directly to where the radio wire comes out of the ignition. That doesn't explain what ignition switch ignition is though :S.

This is based on my limited understanding. What do those numbers mean (like 30, 50, etc...)? I think they are on the wiring diagrams too.

gsmith660 · 02-25-2009, 03:36 AM

You are brave my friend, good luck.

Mr.Puff · 02-25-2009, 03:42 AM

Thanks. This stuff is getting really confusing.

Mr.Puff · 02-25-2009, 03:50 AM

"The alt power wire may be for a system that requires the key to provide a sense signal, usually a dash light, to the alternator to start charging. This type of system lights the dash alt lamp when the key is first turned on, then goes off when the engine is running and the alternator is up to speed. It will then light again if it stops charging.
The wires to the starter would be from the battery, constant battery power may be connected there. The other wire on the starter would be for the solenoid."

Looks like that battery light in the dash takes care of alt exciter for me, and I won't need alt. power either.

gsmith660 · 02-25-2009, 03:59 AM

The Porsche wire harness has so many vehicle specific sub harnesses in there that changing out the entire harness was never a consideration. When I did my fuse panel upgrade I followed the factory harness completely My interpretation of the fuse panel upgrade There is a company that sold the factory wire color codes eagleday I believe If I need to refurb a harness then I intended to get the factory colors and build a harness off the wiring diagram. Once again good luck.

Mr.Puff · 04:12 AM

I'll need it! I'll just keep telling myself it is about the experience

. Put some hair on my chest... make a man out of me... something like that.

That halfway pic of yours looks awfully familiar

. I had originally planned on doing the fuse box that way. Then I found some wires that looked burnt or tarnished in places with some missing insulation. Like they had been chewed on.

gsmith660 · 02-25-2009, 04:13 AM

Yep! LOL These are the things that give us character or kill us.