1973.5T/CIS - that infamous "green wire" to the distributor?

[Sunroof]

I am trying once and for all to solve the "green wire" mystery connected to my distributor. I have looked at wire schematics, seen photos of wire harnesses and cannot figure out just why this wire has to be "green"!! In the wire schematic, one of the three - three pin wires coming off the CDI unit that attaches to the distributor is BLACK. Without taking apart the wire harness from the CDI to the coil and distributor I do not know if the green wire was a splice, add on or simply an OEM requirement for this model and ignition system. Do I need to replace with the same Green wire? I have heard Porsche no longer makes it available. I am thinking it has some mysterious voodoo electronic magic that drives my points.............

What's with it?

Bob
1973.5T

[timmy2]

Post a picture.
I haven't seen a green wire on any stock 73.5 CIS CDI harnesses yet.
Someone may have replaced the white shielded wire Porsche used from '73.5 to '77 in the CDI wiring with a piece from a '78-'83 electronic distributor at some time in the cars history.

[Pazuzu]

Originally Posted by Sunroof

I am trying once and for all to solve the "green wire" mystery connected to my distributor. I have looked at wire schematics, seen photos of wire harnesses and cannot figure out just why this wire has to be "green"!! In the wire schematic, one of the three - three pin wires coming off the CDI unit that attaches to the distributor is BLACK. Without taking apart the wire harness from the CDI to the coil and distributor I do not know if the green wire was a splice, add on or simply an OEM requirement for this model and ignition system. Do I need to replace with the same Green wire? I have heard Porsche no longer makes it available. I am thinking it has some mysterious voodoo electronic magic that drives my points.............

What's with it?

Bob
1973.5T

Yes, it has to be green.

It's not a wire. It's TWO wires, one of which is a shield around the other one. That single "cable" sends a signal out and back, and the shield keep the tiny tiny pulse from getting mushed by the high electromagnetic noise in the engine bay. The tiny tiny pulse is what tells the CDI box to fire a spark, and if it get mushed, then the spark will not fire or fire at the wrong time, and the engine won't run.

The big problem is that the connection at the distributor is proprietary and strange, and so getting a replacement green wire is by far the easiest way to deal with it. The rest of the cable can be replaced with any number of twisted pair wires, or core/shield wire combinations, which can be bought for pennies a foot.

[timmy2]

Mike, he has a '73.5 with points.
No electronic distributor, no reluctor and a 3 pin CDI. And unless the distributor was replaced with an SC one, no plug on the side for the '78-'83 proprietory Bosch green wire.

[timmy2]

Here is a photo of the replacement 73.5 CDI and engine harness I built for someone who sent me their original unmolested one.

Building SC and Mid Year Engine Harnesses

[Pazuzu]

Originally Posted by timmy2

Mike, he has a '73.5 with points.
No electronic distributor, no reluctor and a 3 pin CDI. And unless the distributor was replaced with an SC one, no plug on the side for the '78-'83 proprietory Bosch green wire.

I thought the green wire dated back to all CIS, my mistake. But, if he does have a green wire, then I stick to my story

And maybe my layman's explanation will help the next dude that searches "green wire" in titles and comes across this thread

[Sunroof]

Looks like a single wire to me connected to a right angle copper female fitting on the distributor. I do not see a green wire on the three pin connector so where does it come through, the coil?

I have two different answers on the subject so far. Perhaps that is why it makes this "green wire" so mysterious. If indeed it is a double shielded special set up, where you can get one to replace it. Porsche does not carry it, the replacement wire harnesses for the 73 CIS I have seen that are available do not have a green wire (only black).

???

[Pazuzu]

1973.5T "green ignition wire" trouble

You had troubles with it a few years ago, and it ain't stock.

[timmy2]

Like I said, post a photo of your distributor wiring and we can figure it out.
You have my email and my phone number in my first reply to your PM.
Give me a call.

[timmy2]

Originally Posted by Pazuzu

1973.5T "green ignition wire" trouble

You had troubles with it a few years ago, and it ain't stock.

Lol, I see I didn't pay attention to the model year either in that thread when I replied...

[Sunroof]

That's right, it was several years back and over the years the "green wire" has reared its head up now and then. I have heard from several others who drive the same cars. It might have been a dealer or shop replacement, but it has caused lots of headaches regarding its intended use and if it had any special secret sauce ! Before I invest $$$$$ in some more restoration, I wanted to put the "green wire " concern to its final conclusion. Why a green wire that appears OEM?

[timmy2]

Bob, what colors are the 3 wires at the CDI box 3 pin connector?
2 whites and a red? Or a black, a red and a blue/yellow?
Or something else?
Also what color wire to the coil from the CDI harness?

This should help determine what you have.

[Sunroof]

I will have to take a look Dennis and map those out. If this was re-fabricated harness (hence the green wire), it might be a hodge-bodge of different colors. I have the wire schematic for the 1973CIS version and it shows that coming off the 3-pin CDI unit is a blue/yellow , red and black wire. Nothing green shows up! I have yet to remove the tape shielding.

Bob

[timmy2]

Porsche never updated the prints until '74 to show the new white wire style CDI harness wiring when they changed 1/2 way through the year. I'm betting 1/2 of the CIS cars would have received the older style with the black and blue/yellow wires and seperate shields as they used up their stock.