so i should be able to take a wire from one of my ignition knobs on the instrument panel to the single BW wire looping through the tacho?

Under the dash, there is only one BW wire. It is 12V coil feed. Wire it through the tacho loop.

The 12V coil feed goes directly to the ballast resistor, from there to the coil. When key is to START, another wire bypasses the resistor.

Thanks Dattodude and others, you guys are the ducksnuts !!
Great help and advice much appreciated. Saved me dollars at the sparky's

Cheers

Adam

I can only find one black white tracer in the wiring harness and both sides of my ballast resistor are single terminal.
How do i know which side of my ballast resistor is 12 volts?

Quote:

If it is ignition 12v you can use it. But you should not connect the other end to the coil positive (if you have points ignition) you need to connect it to the ballast resistor 12v side. ( it will work if you connect it to the coil but your points will burn out quicker )

ddgonzal's pics and link explian it simply;


* B - ground - to back of Instrument Cluster
* YR - IG power - to back of Instrument Cluster
* RG - lights (two lights, two wires. Not shown in photo above) to back of Instrument Cluster
* BW - signal loop - to BW wires in dash harness


The BW loop of wire is the current induction coil. The ends, logically speaking, go in between the IG terminal of the ignition switch and the single-terminal (non-coil) side of the Ballast Resistor.

I have two ignition knobs on the back of my speedo. can i take the loop off one of them through the tacho to the black white trace wire?

thanks for the help so far my car is running again.

AS SAID A THOUSANDS TIMES BEFORE
POWER GOES TO + SIDE OF COIL
FROM SWITCH THRU LOOP WIRE ON TACO THEN TO COIL
AS A TRAIL TAKE + LEAD OF COIL
TAKE A WIRE AND CONNECT TO + BATTERY TERNIMAL
CONNECT TO ONE END OF LOOP WIRE(TACO MITE GO RONG WAY IF SO SWOP POWER WIRES ON LOOP OVER)
CONNECT THE OTHER END OF LOOP WIRE TO + COIL TERMINAL
CHECK THAT U HAVE POWER AT TACO WIRES BLACK AND YELLOW
IF CONNECTED AS SAID TACO WILL WORK UNLESS TACO F@!@KED
THIS IS VERY EASY IF U FOLLOW INSTRUCTIONS
IF NOT RING SOMEONE ITS EASYER TO ASK THAN CHANGE LOOMS/PUT OUT A FLAMING CAR
TOMMO 0411797234

Sounds like you have run 12v to your coil. Do you have points? Check them cause they are likely fried.
Sounds like you wired it correctly except you needed to connect it to the 12v side of the ballast resistor and not the coil side. (that is if you have points)

thanks for the replys.

its definately a loop type tacho and the cable that they ran was straight off the coil to the tacho not from the ballast resistor. is it possible ive wrecked the coil or the capacitor on the dizzy or something?

newer 1200 tachometers take a voltage signal
older 1200 tachometers take a current signal

Loop Type (current signal)



Voltage Type



You can use either kind but the wiring is different. 1200 coupes and sedans have a dash wiring for the Loop.

Wiring diagrams are at Tech: Tacho Wiring