the inertia switch in my 87 has gone bad. I have one from a 92 but it has a 3 wire connection where the 87 only has 2. What is the third wire and can I splice the connector from the 92 onto my 87 harness?
Take you meter and measure the resistance across the terminals. When you find 2 terminals that have less than 1 ohm resistance, mark them. Press the reset button on the inertia switch and repeat the measurements using the 2 marked terminals. The reading should not change. If no change, those are the two terminals you need to connect to.