Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC C0129: Low Brake Fluid Circuit HighDTC C0267: Low Brake Fluid Indicated
Diagnostic Fault Information
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Low Brake Fluid Circuit | -- | C0129 | C0129 | -- |
Low Brake Fluid Circuit | C0267¹ | C0267¹ | -- | -- |
¹Low brake fluid level | ||||
Circuit/System Description
The body control module (BCM) monitors the brake fluid level in the master cylinder reservoir via the brake fluid level switch. When the BCM sees the brake fluid level switch input grounded, it sends a class 2 message to the instrument panel cluster (IPC) to turn ON the Red Brake Warning indicator.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
| • | The BCM detects low brake fluid. |
| • | The BCM detects a short to voltage, or an open in the brake fluid level circuit.. |
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. |
| • | The BCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles. |
Diagnostic Aids
The brake fluid level switch has an internal resistor between the fluid level sensor signal circuit and the ground circuit. Even though the switch is open, a resistance value will appear across both terminals of the brake fluid level switch.
Reference Information
Schematic Reference
Connector End View Reference
Hydraulic Brake Connector End Views
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Verify the brake fluid reservoir is up to the proper level.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the brake fluid level switch.
- Test for less than 4 ohms of resistance between the ground circuit terminal 2 and ground.
- Ignition ON, test for 9.6 - 11 volts between the signal circuit terminal 1 and the ground circuit terminal 2.
- If all circuits test normal, test or replace the brake fluid level switch.
| ⇒ | If greater than the specified value, test the ground circuit for an open /high resistance. |
| ⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit test normal replace the BCM. |
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM |
Component Testing
- Ignition OFF, disconnect the harness connector at the brake fluid level switch.
- Test for less than 2300 ohms between the signal terminal 1 and the ground terminal 2.
| ⇒ | If greater than specified value, replace the brake fluid level switch. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM replacement, setup, and programming |
