The brake shut-off valve is supplied ground to Pin 1 from the battery through Pin 4 of the 12-pin connector and then through Pin A of the valve cover gasket. The ECM controls the engine brake by supplying 12 volts through Pin C of the valve cover gasket to Pin 2 of the brake shut-off valve.
Fault Detection / Management
An open or short to ground in the brake shut-off valve control circuit can be detected by an on demand
Output Circuit Check (OCC) during KOEO Standard Test. If there is a circuit fault detected a DTC will be set.
When the engine is running, the ECM compares engine brake control pressure to injection control pressure and BCP desired. When the brake is activated, brake control pressure will equal injection control pressure.
If the brake control pressure does not match injection control pressure, the ECM will disable the engine brake, a DTC will be set, and the amber ENGINE lamp will be illuminated.
When the engine brake is not active and the ECM detects an undesired value, the ECM will set a DTC and the amber ENGINE lamp will be illuminated.
A bias BCP sensor can also cause the fault. The brake shut-off valve and the BCP sensor circuit should both be diagnosed.
Brake Shut-off Valve Diagnostic Trouble Codes (DTCs)
DTCs are read using the EST or by counting the flashes from the amber and red ENGINE lamp.
DTC 247
Engine brake enable OCC self-test failed
• DTC 247 is set by the ECM when the OCC test has failed after the KOEO Standard Test has been run.
• DTC 247 can be set when a poor connection, an open or short to ground in the brake shut-off valve control circuit, or a failed brake shut-off valve solenoid exists.
• When DTC 247 is active the amber ENGINE lamp will be illuminated.
DTC 546
Engine brake control pressure below expected range
• DTC 546 is set by the ECM when the brake control pressure is less than injection control pressure 4 MPa (580 psi) for more than 3 seconds.
• DTC 546 can be set due to a bias low BCP sensor or a failed BCP sensor. See “Brake Control Pressure (BCP) Sensor – Section 7.
• DTC 546 can be set due to an open control circuit (power or ground), a failed brake shut-off valve, or a failed brake shut-off valve solenoid.
• When DTC 546 is active the amber ENGINE lamp is illuminated.
DTC 547
Engine brake control pressure above expected range
• DTC 547 is set by the ECM when the brake control pressure is greater than desired brake control pressure by 4.5 MPa (653 psi) for more than 3 seconds.
• DTC 547 can be set due to an open signal ground, VREF shorted to a voltage source higher than 5.5 V, or a failed BCP sensor. See “Brake Control Pressure (BCP) Sensor – Section 7.
• DTC 547 can be set due to a control circuit short to B+ or a brake shut-off valve stuck open.
• When DTC 547 is active the amber ENGINE lamp is illuminated.
Tools
• EST with MasterDiagnostics® software
• EZ-Tech® interface cable
• Digital Multimeter (DMM)
• VC Gasket Breakout Harness
• 12-Pin Breakout Harness
• 500 Ohm Resistor Harness
• Breakout Box
• Terminal Test Adapter Kit
