tachometer problems

[rjrandalls]

1974 2.0 L

Tach began having problems intermittently. For awhile it would not work after starting but within several minutes it would begin to oscillate wildly and then after another few minutes of driving it began to work normally.

Now it's completely weird! Interestingy it goes to 7000 and stays there when I turn the ignition key halfway, then goes to 600 or so and stays there after startup. It oscillates from 600 to 7000 with the signal activated.

Where is the problem likely to be? I checked and cleaned all connection at the back of the unit and at the coil. Any additional help would be greatly appreciated! I love my tach and I want it back!

[Dave at Pelican Parts]

Check your points and condensor. Check the connections in the black/purple wire that goes from the coil to the relay board to the tach.

If those don't turn up anything, see if you can find a known-good tach to try as a test.

--DD