tachometer not working

whizkidder wrote: The power from your resistance wire should go to the rear stud on the starter selenoid. The blue fron the tach harness goes there also. The yellow from the tach harness goes to the plus on the coil. The original jumper from the rear stud to coil plus is not connected. This way, juice from the switch goes thru the resistance wire, back through the tach, and to the coil. When you engage the starter, the selenoid sends full 12v thru the tack to the coil.

One thing. I believe the pink wire is supposed to be disconnected if you have the tach. That wire is the resistance wire from the wiring harness. In a car with the tach wired into the circuit you leave that disconnected because the tach itself provides the resistance function.  

ccowx wrote: One thing. I believe the pink wire is supposed to be disconnected if you have the tach. That wire is the resistance wire from the wiring harness. In a car with the tach wired into the circuit you leave that disconnected because the tach itself provides the resistance function.   I hope that helps, Chris

ga70amx wrote: ccowx wrote: One thing. I believe the pink wire is supposed to be disconnected if you have the tach. That wire is the resistance wire from the wiring harness. In a car with the tach wired into the circuit you leave that disconnected because the tach itself provides the resistance function.   I hope that helps, Chris    There was no pink wire hooked into my solenoid circuit when I changed alternators. The only pink wire in the engine compartment came off the voltage regulator and went straight to the alternator.

That "pink" was actually orange - faded most likely.
You don't see the resistance wire in most cases, it's up the line. What confuses things quite often is the fact that the yellow ignition is also tied to the regulator, so there's multiple yellow, and splices are up the line and it gets confusing.
The scan from the TSM actually "says it all" - to me, anyway.
Ignore text, look at the picture. That's all one needs to do. At least for me, the first time all those years ago when I SAW an example, it made perfect sense. The explanation from someone trying to "tell me" how it was wired didn't work out in my head. One look at a car, or the TSM and I had it down.

You'll have that L-shaped push-on connector hanging.
You will move the yellow wire that originally went to the coil + terminal and take it off the coil and put it on the I terminal on the starter relay.
No, you are not taking the resistance wire out of the picture, but instead of it supplying the coil directly, it now supplies the TACH, then through the tach, back out and to the coil.
The yellow you moved FROM the coil +  TO the starter relay I is what the "pink" or resistance wire FEEDS. So instead of feeding the coil, it's "feeding" the tach, THEN to the coil.
The resistance wire is still there in use.
That L shaped connector you have hanging now? That is from the ignition switch - switch through resistance to relay I, ties to yellow wire going to coil +. When you turn on the key, it feeds the coil through the resistance wire - and is actually ALSO connected to the I.
See where it says "leave this disconnected" or something like that? THAT is where the PINK resistance and YELLOW that feeds the coil are connected. They are STILL connected - inside the L connection you leave hanging.
Pink to the connector, then to the yellow, then to the coil +

In other words, if you follow that TSM scan -
all you have done is pull the yellow off the coil and instead connect it to the input of the tach using the relay I terminal as a simple junction block. Then the output of the tach goes to the coil.
Nothing else has changed.
The pink still feeds the yellow which fed the coil (because pink and yellow STILL join inside that connector you left hanging), but now the yellow feeds the tach,  THEN the coil through the tach.
You simply have put the tach in SERIES with the rest of the system - just ahead of the coil.





Edited by billd - Jan/10/2013 at 7:00am