System Relay Output Circuit

NAME OF CODE:
System Relay Output Circuit

WHEN MONITORED:
The test is conducted after the system relay is turned on and the vehicle speed is above approximately 6 MPH. The system relay output voltage is tested once each 5 ms.

SET CONDITION:
The system relay supplies the Controller, Anti-lock Brake (CAB) solenoid drivers with B(+) power at cavity 47 when it is commanded on by the CAB. It Is turned off by the CAB to shut off Anti-lock Brake System (ABS) functions in the event of a trouble code or a loss of B(+) to the system. The system relay is supplied B(+) through the relay box from the ignition switch (fuse protected). The trouble code is stored if the system relay output voltage at cavity 47 is below 9 volts or above 20 volts for 1 second while in ABS cycling or 20 seconds if not in ABS cycling.

POSSIBLE CAUSES:
- CAB malfunction trouble code
- System relay control circuit trouble code
- Open relay box ground circuit
- Open fused B(+) to the system relay
- Loose or corroded connector terminals
- System relay output circuit shorted to ground
- System relay output circuit shorted to B(+)
- Open system relay contacts
- Open system relay output circuit
- Failed relay box
- Open system relay control circuit