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Home >> GMC >> 1974 >> Magnavan >> Repair and Diagnosis >> Engine Performance >> Ignition System >> Transmission Controlled Spark System >> Operation >> 1970 Relay Switch

1970 Relay Switch

Relay is an electrically operated on-off type switch. When coil is energized through temperature switch, it opens normally closed relay points thereby opening circuit to vacuum advance solenoid, which then de-energizes and opens vacuum port providing vacuum to distributor vacuum advance unit.