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67 BJ8 3000 Tach Wiring

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R

R&M

Senior Member
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Have a 67 BJ8 3000 MkIII. New wireing harness was put in but tach does not work & does not look to be wired properly.

At the back are the 2 male spade posts for the white wires. Should the tach be wired with the from the white coil wire to the tach & then out of the tach through the ignition switch? or ?????????

Any insite would be appreciated.

Thanks,
R&M /ubbthreads/images/graemlins/confused.gif
 
On my BJ8 the white wire loops through a tiny "current transformer" inductively coupling the ignition primary circuit. The loop goes round a plastic former with metal tabs that completes the magnetic circuit of the transformer and is held in by a knurled nut.
 
Here's how my tach was wired when I got my car. Can't remember which direction the white wire loops. [image]https://www.britishcarforum.com/ubbthreads/download.php?Number=100497[/image]
 
The tach will not work if the loop goes the wrong way. If the car is positive ground it goes one way, if negative, it goes the other. On my 64 BJ8, positive ground, the wire from the ignition switch starts through the pickup from the outside edge of the tach, loops around, and then comes out toward the inside of the tach (center) and goes to the wire harness and on to the coil. Mind you, this was determined looking under the dash with a small flashlight into a mase of wires. I think I am correct. If your tach does not work, just reverse the loop. From your picture I can not tell where the wire comes from or is headed.
 
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