1990 chevy lumina tach wire

Hello, I have a 1990 Chevy Lumina car and am looking for the tach wire. I know it's a white or WHITE/ purple wire that comes to the coil but when i look at my coil i have only a purple and PURPLE / white wire. Both of these wires don't work. Does anybody have any other suggestions or where the wire comes from or where else i can look? Thanks in advance, Mike

Is this a single coil? If so have you tested? One should read 12volts+ with the ignition, it's the other one you want.

The wire should be PURPLE / white. Is your r/s unit set to tach sensing? Have you tested the PURPLE / white to confirm that the voltage rises and falls with the increase and decrease of engine rpm, respectively?This information is provided only as a reference.

All circuits should be verified with a digital multi-meter prior to making any connections.

To test tach, set your DMM to 20VAC. Black probe to ground, red to suspect wire with the engine running. You should get between 3-5VAC with it increasing slightly as you rev up.