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Posted by: Geezer914 Jun 4 2011, 02:55 PM

Throw the wiring diagram out the window! Can anyone tell me how these wires are attatched to the coil? All three are black, but the single wire has a blueish cast. I can not find the black and purple wire for the tach. Both wires are hot when the key is in the run position. What is with the small and large wires attached together? Stumped!!! Car is a 1975 914 L Jet injection.

Posted by: Jeff Bowlsby Jun 4 2011, 03:09 PM

http://bowlsby.net/914/WiringHarnesses/HarnDia_IGN_74-75L-Jet.pdf

Your welcome!

The paired wires at the coil are a single circuit that connects to the double relay.

Posted by: jim_hoyland Jun 4 2011, 03:21 PM

The 12 pin connecter at the rear of the relay board ihas slots numbered like:
1 2

3 4

5 6

7 8

9 10

11 12

I have a '75 LJet too:

The black wire originates from pin seven and goes to the +coil AND to 86C of the dual relay. The dual relay has a left and right side: 86C is on the left side toward the rear of the car and to the right ( see Jeff's diagram, it's # 9 )

The tach wire originates from pin 5 ( corrected) and goes to the -coil. The purple trace may have faded.

There is also a white or grey trigger wire that goes to the - coil

I don't have points, someone else may chime in here

Posted by: Geezer914 Jun 4 2011, 03:47 PM

So the two wires connect together go to the + side of the coil. If the single wire is the tach wire, and connects to the - side, why is it hot with the key on? Thanks for the quick replys

Posted by: jim_hoyland Jun 4 2011, 03:59 PM

Tach wire must go to - coil. The hot blacks to to the + coil and to 86C of dual relay

Posted by: Geezer914 Jun 4 2011, 04:23 PM

Why is the tach wire hot with the key on? We had it hooked up to the - side of the coil and it was shorting the coil and not sending spark to the plug wires.

Posted by: jim_hoyland Jun 4 2011, 05:56 PM

You verified it is the tach wire ?

Posted by: Geezer914 Jun 4 2011, 07:50 PM

That's all the wires in that harness. The single black wire should be the tach wire. But like I said it's hot with the key on. How can I check to be shure its the tach wire?

Posted by: jim_hoyland Jun 4 2011, 08:39 PM

Disconnect the 12 pin connector at the rear of the relay board; disconnect all wires from the coil; then, do a continuity test from pin 5 ( not seven) on the 12 pin connector to each of your suspected tach wires.

*** Corrections: Pin 5 is Tach

Posted by: Geezer914 Jun 5 2011, 03:26 AM

Thanks every one for all your help!