Antilock Brake System (ABS): 1212

1212-CAB SYSTEM OVER VOLTAGE





When Monitored and Set Condition
^ When Monitored: Ignition on. The Controller Antilock Brake (CAB) monitors the Fused B(+) circuit at all times for proper system voltage.
^ Set Condition: If the voltage is above 16 volts for greater than 500 milliseconds (ms), the Diagnostic Trouble Code (DTC) is set.

POSSIBLE CAUSES
SYSTEM VOLTAGE HIGH
GROUND CIRCUIT OPEN
CONTROLLER ANTILOCK BRAKE (CAB)
For a complete Antilock Brake System (ABS) Circuit Diagram, (Refer to - BRAKES/ELECTRICAL - SCHEMATICS AND DIAGRAMS).

Diagnostic Test
1. WITH THE DRBIII READ DTCs





Turn the ignition on. With the DRBIII, erase DTCs. Turn the ignition off. Turn the ignition on. Start the engine. With the DRBIII, read DTCs.
Does the DRBIII display a System Over voltage DTC?
Yes >> Go to 2
No >> The condition that caused this DTC to set is currently not present. Inspect the related wiring harness for a possible intermittent condition.

2. MEASURE THE BATTERY VOLTAGE





Start the engine. Raise engine speed above 1,800 RPM. Measure the battery voltage.
Is the voltage above 16 volts?
Yes >> Refer to the appropriate service information for charging system testing and repair. Perform ABS VERIFICATION TEST. ABS Verification Test
No >> Go to 3

3. MEASURE THE RESISTANCE OF THE GROUND CIRCUIT





Turn the ignition off.
Disconnect the CAB connector.

Note: Check connector - Clean/repair as necessary.

Measure the resistance between ground and the Ground circuit at the CAB harness connector.
Is the resistance below 5.0 ohms?
Yes >> Go to 4
No >> Repair the Ground circuit for an open. Perform ABS VERIFICATION TEST. ABS Verification Test

4. MEASURE THE RESISTANCE OF THE GROUND CIRCUIT





With the ignition off. Measure the resistance between ground and the Ground circuit at of the CAB harness connector.
Is the resistance below 5.0 ohms?
Yes >> Replace the Controller Antilock Brake (CAB) Module. Perform ABS VERIFICATION TEST. ABS Verification Test
No >> Repair the Ground circuit for an open. Perform ABS VERIFICATION TEST. ABS Verification Test