Charts A-2 To A-4: Main Relay CKT

WARNING: This page is about a different car, the 1988 Pontiac Bonneville. However, it is still accessible from the selected car via links, so may be relevant.

Main relay circuit provides battery voltage to ECBM to power main valve, solenoid valves, logic circuit and some self- diagnosis circuits. Main relay coil receives power from ECBM pin No. 8.
ECBM does not apply power to main relay coil until after ECBM receives ignition enable circuit information. Relay is grounded at ABS ground junction, located on left fender rail. Power for main relay comes through a fusible link from battery junction box.

Fig 1: Chart A-2 Main Relay Ground Circuit

Fig 2: Chart A-3 Main Relay Coil Circuit

Fig 3: Chart A-4 Main Relay Power Circuit