For 1990-2009 cars

### Circuit Description

The body control module (BCM) monitors the brake fluid level in the master cylinder reservoir via the brake fluid level switch.

### Conditions for Running the DTC

The ignition switch is in the ON position for 60 seconds or more.

### Conditions for Setting the DTC

• | The BCM detects a low brake fluid level condition for more then 60 seconds.

• | The BCM detects a short to voltage in the brake fluid level signal circuit.

• | The BCM detects an open in the brake fluid level signal circuit.

### Action Taken When the DTC Sets

The red brake warning indicator turns ON.

### Conditions for Clearing the DTC

The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.

### Diagnostic Aids

A lower than normal brake fluid level in the master cylinder may cause the brake fluid level switch to close when the vehicle makes sharp turns or sudden stops. Low brake fluid level may be caused by a brake fluid leak or worn disc brake pads.

Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Brake Warning System Schematics Connector End View Reference: Body Control System Connector End Views in Body Control System
1 | Did you perform the hydraulic brake Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Hydraulic Brakes
2 |

1. Use a scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC C0129 or C0267 set as current?

Go to Step 3

Go to Diagnostic Aids

3 | Inspect the brake fluid level in the master cylinder reservoir. Refer to Master Cylinder Reservoir Filling . Did you find and correct the condition? | Go to Step 8 | Go to Step 4
4 |

1. Disconnect the brake fluid level switch harness connector.
2. Use the scan tool to observe the Brake Fluid Level status.

Does the scan tool display Low?

Go to Step 6

Go to Step 5

5 | Replace the brake fluid level switch. Refer to Brake Fluid Level Indicator Switch Replacement . Did you complete the replacement? | Go to Step 8 | --
6 |

1. Turn OFF the ignition.
2. Disconnect the BCM harness connector.
3. Test the brake warning indicator supply voltage circuit for a short to ground, short to voltage, or open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 7

7 | Replace the BCM. Refer to Body Control Module Replacement in Antilock Brake System. Did you complete the replacement? | Go to Step 8 | --
8 |

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 3

System OK