1000 - 1999: 1212

1212 - CAB SYSTEM OVERVOLTAGE

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.

For a complete Antilock Brake System (ABS) Circuit Diagram Brakes - ABS Electrical Diagnostics.

Diagnostic Test

1. WITH THE SCAN TOOL, READ DTCs
Turn the ignition on.
With the scan tool, erase DTCs.
Turn the ignition off.
Turn the ignition on.
Start the engine.
With the scan tool, read DTCs.
Does the scan tool display a System Overvoltage 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.
- Refer to the ABS-INTERMITTENT CONDITION TEST. ABS Intermittent Condition Test

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 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. Removal.
- Perform ABS VERIFICATION TEST. ABS Verification Test

No

- Repair the Ground circuit for an open.
- Perform ABS VERIFICATION TEST. ABS Verification Test