Circuit Operation
System power is provided through the Over-Voltage Protection Relay (OVPR). This relay includes a special diode arrangement which will interrupt power to the Anti-Lock Brake System in the event of excessively high system voltage. This relay will cause the 20 amp brake fuse (fuse No. 1 in the maxi fuse panel) to blow if high system voltages are encountered. Should an over-voltage situation occur, the relay will not be damaged and can be used again.
The OVPR coil is powered through the 7.5 amp in-line brake fuse, located under the dash near the EBCM connector. The relay coil is provided both power and ground whenever the ignition is in the run position, meaning that the system should be receiving power anytime the ignition is ON. See Fig 1 .
CKT 850 distributes power to the ABS when the relay contacts are closed. Components which receive power from this circuit include:
- EBCM - Pin 1
- Sensor Block - Pins 3 and 4
- Pump Relay Connector (for relay coil) - Pin 4
CKT 850 is provided battery voltage through the 20 amp Brake fuse in the maxi fuse panel.
CKT 2 (EBCM pin 11) is used to keep power to the EBCM after the ignition is turned off. This allows the EBCM to store any diagnostic codes which may be set.