Tachometer wiring differences 2.7 and 3.0

[NeedSpace]

Problem resolved.

So, this is what I did. While I am not exactly sure where my wiring is astray, I found a solution that worked.

First, someone suggested that I connect the silver wire exposed here to the distributor point. While this made NO sense to me, I gave it a shot. All this did was keep the engine from starting.


Then I did the other suggestion which was connect the #12 pin of the 14 pin connector to the distributor point. Here is how I wrapped the wire around pin 12.


Then I wrapped this wire around the wiring harness and then crimped it with the wire at the distributor.



And now officially, I have a working tach! Thanks for all your help!

[tonykara]

This is the same problem I face now. I have a 'newer' 3.0 liter engine in my '75 (which had a 2.7 liter) and the tach doesn't work. The wire on the side of the distributor is green and goes into some sealed connector as shown in this picture. It looks different than the cream colored wire with the lug shown in your picture. Is there some other good spot to run that black wire you ran from the 14 pin connector? What is this actually connecting?

[julahti]

I have a 77 2.7 and all electronics from it, on a 78 SC, and I am not able to get the tach working. Is this a compatibility issue and is there a solution to it? I have the black/purple wire now hooked into points as in 1977 wiring diagram, but what I am reading here is that 78 SC tach is getting the signal straight from CDI box.

[timmy2]

Tach wire on a '78 body harness runs to pin 12 of the male 14 pin connector.
On the '77 body harness it runs to the white 2 wire connector below the CDI.

The '77 engine harness needs to be changed to get the tach signal wire out of the white 2 wire connector and over to pin 12 of the 14 pin female connector.

If you want the CIS safety switch for the fuel pump to work, you need to run the single brown/black engine harness wire to the white 2 wire connector below the CDI where you removed the tach signal wire.

[julahti]

Originally Posted by timmy2

Tach wire on a '78 body harness runs to pin 12 of the male 14 pin connector.
On the '77 body harness it runs to the white 2 wire connector below the CDI.

The '77 engine harness needs to be changed to get the tach signal wire out of the white 2 wire connector and over to pin 12 of the 14 pin female connector.

If you want the CIS safety switch for the fuel pump to work, you need to run the single brown/black engine harness wire to the white 2 wire connector below the CDI where you removed the tach signal wire.

Thanks.

Yes, on SC 14 pin connector the black/purple tach wire is on pin 12. I don't have the 14-pin plug at the moment, just a wire screw block. My black/purple is connected to points/C-terminal of CDI so I believe that is how it is done in pre-sc according to the wiring diagram. The SC tach is not doing anything though....a voltage compatibility issue or shot tach?

CIS safety switch: isn't the safety switch connected to the D- of Alternator/Voltage regulator? Just a ground, right? That's how I have it connected but I still have the fuel pump running all the time. I tried to ground the 85 of the fuel relay, but that didn't cut off the pump either...? Am I wrong here?

[timmy2]

Here is the '77 schematics.
Print and compare to the '78 and you will see the changes to make as I described.

https://www.dropbox.com/sh/jxno8o6qae3roun/AADW1qBcRc53LoEG0TPbRwFva?dl=0