LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> GMC >> 1974 >> Magnavan >> Repair and Diagnosis >> Engine Performance >> Theory and Operation >> Computer Command Control >> Operation >> Reversing Relay
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Reversing Relay

Reversing relay is a magnetically controlled two position switch. In its normally closed position lever makes contact with ground terminal and completes a circuit through CEC solenoid. Contact is broken when transmission mounted switch points are closed which completes a circuit from battery through ignition switch. This circuit sets up a magnetic field in relay which pulls points open and breaks circuit to CEC solenoid, de-energizing it and blocking vacuum to distributor advance unit. When transmission is in high gear, transmission switch points open, breaking circuit from battery through ignition switch and reversing relay. Reversing relay points close, thus providing a circuit through grounded relay to CEC solenoid, energizing solenoid and providing vacuum to distributor advance unit.

Fig 1: 1971 COMBINED EMISSION CONTROL (CEC) SYSTEM
G09325378Courtesy of GENERAL MOTORS COMPANY