1970 911t tach wire

[911Tfan]

Hi,
Does anyone know where the tach wire is hooked up to get it's signal. In working on the ignition I somehow removed the wire and can't remember which wire it was and where it attaches. After the work done the tach no longer works.
Thanks

[timmy2]

Purple/black wire comes out of engine harness with the black oil temp wire. It attaches to the points at the distributor together with the black wire from the CDI harness.
It goes to pin 9 in the female 14 pin connector and from there into the rear fuse panel harness and devices that work their signal conditioning magic, then out the other 14 pin connector to the dash area.

[Trackrash]

On a '70 if you have the "intermediate" unit, which most '70s have , the wire is hooked to the coil terminal 15.

[Trackrash]

My early '71 had this set up. It was used from '69 to early '71.

BTW, on my car the wire that runs from the coil to the intermediate unit is blue/yellow and not the red/white as shown in this diagram.

[timmy2]

Here is the factory 70 diagram showing exactly what I posted.
https://www.dropbox.com/s/32266dstkfqnwrx/SL35-Master.pdf?dl=0

[Trackrash]

Interesting, on your diagram there are TWO black with purple wires. The one from the points goes to the speed switch and is not the tach wire. Probably only on the E and S for the FI.

[timmy2]

Yes, the ‘69 T’s were different like your posted diagram shows. as I have that diagram for the ‘69T.

I don’t have, nor have I seen a factory diagram for the ‘70 T that is different, the one I do have from my factory manuals, indicates it is for all 3 models.
But, knowing Porsche’s lack of attention to wiring details in the manuals, I’m not surprised. They are full of small mistakes in the wire colors actually used.