For 1990-2009 cars

### Circuit Description

The brake fluid level switch monitors the level of brake fluid in the master cylinder. When the instrument panel cluster (IPC) detects the brake fluid level switch input grounded, it will illuminate the red Brake indicator and send a serial data message to the electronic brake control module (EBCM) that tells the EBCM that the brake fluid level is low.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0126 Low Brake Fluid Level Indicated

### Conditions for Running the DTC

The ignition switch is turned ON.

### Conditions for Setting the DTC

Low brake fluid is detected for 2 seconds.

### Action Taken When the DTC Sets

The red BRAKE warning indicator turns ON.

### Conditions for Clearing the DTC

• | The condition for setting the DTC is no longer present and the DTC is cleared with a scan tool.

• | The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

### Diagnostic Aids

Inspect the master cylinder reservoir for the proper brake fluid level.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: DTC C0126 Connector End View Reference: Antilock Brake System Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Inspect the brake fluid level. Is the brake fluid level OK? | Go to Step 3 | Go to Hydraulic Brake System Bleeding
3 |

1. Install the scan tool.
2. Key on, engine off.
3. With a scan tool, observe the Brake Fluid Switch parameter in the Instrument Panel Cluster data list.

Does the scan tool indicate that the Brake Fluid Switch parameter is Low?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 4

4 |

1. Turn OFF the ignition.
2. Disconnect the brake fluid switch.
3. Key on, engine off.
4. With a scan tool, observe the Brake Fluid Switch parameter.

Does the scan tool indicate that the Brake Fluid Switch parameter is Low?

Go to Step 5

Go to Step 6

5 | Test the signal circuit of the brake fluid level switch for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 10 | Go to Step 7
6 | Inspect for poor connections at the harness connector of the brake fluid level switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 10 | Go to Step 8
7 | Inspect for poor connections at the harness connector of the instrument panel cluster (IPC). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 10 | Go to Step 9
8 | Replace the brake fluid level switch. Refer to Brake Fluid Level Indicator Switch Replacement . Did you complete the replacement? | Go to Step 10 | --
9 | Replace the IPC. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 10 | --
10 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2