Simple 4 Pin Relay Diagram

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[1990TSIAWDTALON]

Update 9/26/2022: This is something that my son ran into this month so I am adding it to the relay description. He was running 2 Spal fans on his car (1986 Camaro Z28) and we were having issues with the car "running on" after he would switch the key to off. The car would continue to run for a few seconds and then finally die. It was not "dieseling", it was just continuing to run as if we had not turned off the ignition. I finally came to the conclusion that our big Spal fans were producing electrical current back to the ignition circuit, back feeding through the relays (one for each fan). I had NEVER thought of this before but my EE background came to the rescue. We installed one Schottky 20SQ050 Diode in line with the power feed to each fan, after the relay, and it resolved the issue of the car not shutting down as soon as we would kill the ignition.
The diagram would go like this if you are worried or are having this same issue. Spinning fans generate electricity while they are spinning, so this will contain that electricity.

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