Cis to pmo no tach?

[xjoegtix]

Hey guys!!
So I'm finally finish with my engine rebuild its all together and running! I still can't believe it.

I have some questions for you though. I'm sure they're deep in the forums but I can't seem to find them.

My tach isn't working and hasn't since I bought the car. I bought it with basically everything broken and crappy old cis. So I assume it could just be the tach is just junk. I was told when i was done with the engine id have to figure out some weird way to make my stock tach work. I just can't seem to figure it out.

I Havant taken any of the old cis wires out of the bay yet because I wasn't 100% sure if I'd need them or not.

Am I missing something?








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[brianlay]

What year engine/chassis?
What ignition system?

[Charles Freeborn]

Generally CIS and tach circuits are unrelated. Tach will be part of the CDI system, or ignition circuits.

[timmy2]

Originally Posted by brianlay

What year engine/chassis?
What ignition system?

^^^^^this???

[SoyRacer]

Originally Posted by timmy2

^^^^^this???

x2

[xjoegtix]

Oh yes! Sorry it's a 1980 euro sc. Has a 6 pin cdi box


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[xjoegtix]

I'm not sure if that helps


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['76 911S 3.0]

Black wire with a purple tracer should be your tach lead from the CDI

[timmy2]

Black/violet wire runs from CDI 6 pin connector back over to female 14 pin engine harness connector, then directly to the back of tach terminal TD.
Test for continuity with an ohmmeter (very low if not zero ohms). If you have continuity from tach to 6 pin on the black/violet wire, then suspect power to the tach on red/black wire at tach, a ground, or the tach itself.

[xjoegtix]

Thank you so much! I'm going to go home and try all that today. I'll let you guys know how it goes


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[xjoegtix]

So I finally got around to doing this. Been busy like crazy.

I check continuity and I didn't have any so I ran a wire around from the tach to the back of the cdi just to check and the tach worked!

I found that someone cut the wire and took the pin out of the 14 pin connector. I made my own pin and connected it to the old black and purple wire and plugged the 14 pin connected in and everything works great now.



Thanks so much guys!


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[timmy2]

Good job finding and repairing your harness.
PO's hacks are one of the reasons I am so busy building harnesses.

[xjoegtix]

I wonder why they cut the wire. So weird.


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[obscene]

Originally Posted by xjoegtix

I wonder why they cut the wire. So weird.


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to install one of these bad boys!