Diagnostic Routine L
Diagnostic Routine L
Diagnostic Overview
The Brake Warning Indicator is Always On
Refer to Wiring Diagram Set 60 for schematic and connector information Electrical Diagrams.
Normal Operation and Fault Conditions
REFER to Brake Warning Indicator , REFER to Park Position Detect Switch and REFER to Brake Fluid Level Switch .
NOTE: The ABS (Anti-Lock Brake System) warning indicator, stability-traction control indicator (sliding car icon), stability-traction control disabled (sliding car OFF icon) and the brake warning indicator illuminate if the input to illuminate the brake warning indicator is sent by the ABS (Anti-Lock Brake System) module.
If the brake warning request message is missing from the BCM (Body Control Module) for more than a programmed length of time, the BCM (Body Control Module) and the IPC (Instrument Panel Cluster) set DTC (Diagnostic Trouble Code) U0121:00 and defaults the brake warning indicator on.
If the parking brake warning request or brake fluid level low message are missing from the BCM (Body Control Module) for more than the programmed preset time, the IPC (Instrument Panel Cluster) sets DTC (Diagnostic Trouble Code) U0140:00 and defaults the brake warning indicator on.
BCM (Body Control Module) DTC Fault Trigger Conditions
Visual Inspection and Diagnostic Pre-checks
- Inspect the base brake system and the parking brake system for correct operation.
- Check for signs of connector terminal damage, corrosion, bent or damaged pins. Inspect the brake fluid level switch for signs of any external damage.
- Verify the parking brake is fully released and the brake fluid is not low prior to carrying out the diagnostics.
Pinpoint Test
1. RETRIEVE THE RECORDED DTCs (Diagnostic Trouble Codes) FROM THE IPC (Instrument Panel Cluster) SELF-TEST
1. Ignition ON.
2. Using a scan tool, perform the IPC (Instrument Panel Cluster) self-test.
Are any DTCs (Diagnostic Trouble Codes) recorded?
2. RETRIEVE THE RECORDED DTCs (Diagnostic Trouble Codes) FROM THE BCM (Body Control Module) SELF-TEST
1. Using a scan tool, perform the BCM (Body Control Module) self-test.
Are any DTCs (Diagnostic Trouble Codes) recorded?
3. RETRIEVE THE RECORDED DTCs (Diagnostic Trouble Codes) FROM THE ABS (Anti-Lock Brake System) MODULE SELF-TEST
1. Using a scan tool, perform the ABS (Anti-Lock Brake System) module self-test.
Are any DTCs (Diagnostic Trouble Codes) recorded?
4. CHECK THE PARKING BRAKE WARNING INDICATOR SWITCH PID (Parameter Identification)
1. Using a scan tool, view the BCM (Body Control Module) parking brake position switch PIDs (Parameter Identifications).
2. Monitor the parking brake PID (Parameter Identification) (PARK_BRK_SW) with the parking brake released.
Does the PID (Parameter Identification) agree with the parking brake position?
5. CHECK THE PARKING BRAKE WARNING INDICATOR SWITCH
1. Ignition OFF.
2. Disconnect: Parking Brake Switch.
3. Ignition ON.
4. Using a scan tool, view the BCM (Body Control Module) parking brake position switch PIDs (Parameter Identifications).
5. Monitor the parking brake PID (Parameter Identification) (PARK_BRK_SW) with the parking brake released.
Does the PID (Parameter Identification) indicate the parking brake is released?
6. CHECK THE PARKING BRAKE WARNING INDICATOR SWITCH INPUT CIRCUIT FOR A SHORT TO GROUND
1. Ignition OFF.
2. Disconnect: BCM (Body Control Module) C2280C.
3. Measure:
Is the resistance greater than 10,000 ohms?
7. CHECK THE BRAKE WARNING INDICATOR USING THE BRAKE FLUID LEVEL SWITCH
1. Ignition OFF.
2. Connect a fused jumper wire:
3. Ignition ON.
4. Wait 1 minute.
Does the brake warning indicator turn off?
8. CHECK THE BRAKE FLUID LEVEL SWITCH GROUND CIRCUIT FOR AN OPEN
1. Ignition OFF.
2. Measure:
Is the resistance less than 3 ohms?
9. CHECK THE BRAKE FLUID LEVEL SWITCH INPUT CIRCUIT FOR AN OPEN
1. Disconnect: BCM (Body Control Module) C2280A.
2. Measure:
Is the resistance less than 3 ohms?
10. CHECK FOR CORRECT BCM (Body Control Module) OPERATION
1. Ignition OFF.
2. Disconnect and inspect all BCM (Body Control Module) connectors.
3. Repair:
- corrosion (install new connector or terminals- clean module pins)
- damaged or bent pins- install new terminals/pins
- pushed-out pins- install new pins as necessary
4. Reconnect the BCM (Body Control Module) connectors. Make sure they seat and latch correctly.
5. Operate the system and determine if the concern is still present.
Is the concern still present?
