C0049

C0049-7B-BRAKE FLUID - LOW FLUID LEVEL

For a complete wiring diagram, refer to the Wiring Information.








- When Monitored:
With the ignition on.

- Set Condition:
When the Body Control Module (BCM) indicates that the Brake Fluid Level Circuit is less then 0.68 volt. The BCM has a 15 sec debounce, except at power-up when it is two seconds if the fluid was low on the previous ignition cycle.





Diagnostic Test

1. CHECK BRAKE FLUID LEVEL

NOTE: This DTC must be active for the results of this test to be valid.

1. Check the brake fluid level.

Was the brake fluid level low?

Yes

- Repair as needed.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

No

- Go To 2

2. BRAKE FLUID LEVEL SWITCH SIGNAL VOLTAGE BELOW 0.68 OF A VOLT
1. Ignition on, engine not running.
2. With the scan tool, read Brake Fluid Level Switch Sense voltage in the BCM.

Is the voltage below 0.68 of a volt?

Yes

- Go To 3

No

- Perform the ABS INTERMITTENT CONDITION diagnostic procedure. Initial Inspection and Diagnostic Overview.

3. BRAKE FLUID LEVEL SWITCH INTERNAL FAILURE
1. Turn the ignition off to the lock position.
2. Disconnect the Brake Fluid Level Switch harness connector.
3. Ignition on, engine not running.
4. With the scan tool, read the Brake Fluid Level Switch voltage in the BCM.

Is the voltage approximately 5 volts?

Yes

- Replace the Brake Fluid Level Switch. Brake Fluid Level Switch - Removal.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

No

- Go To 4

4. CHECK THE (B20) BRAKE FLUID LEVEL SWITCH SENSE CIRCUIT FOR A SHORT TO VOLTAGE IN THE HARNESS
1. Turn the ignition off.
2. Disconnect the Brake Fluid Level Switch harness connector.
3. Disconnect the BCM harness connector.
4. Turn the ignition on.
5. Measure the voltage between ground and the (B20) Brake Fluid Level Switch Sense circuit.

Is there any voltage present?

Yes

- Repair the short to voltage in the (B20) Brake Fluid Level Switch Sense circuit.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

No

- Go To 5

5. CHECK THE (B20) BRAKE FLUID LEVEL SWITCH SENSE CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition off to the lock position.
2. Measure the resistance of the (B20) Brake Fluid Level Switch Sense circuit in the Brake Fluid Level Switch harness connector to ground.

Is the resistance below 100 Ohms?

Yes

- Repair the (B20) Brake Fluid Level Switch Sense circuit for a short to ground.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

No

- Go To 6

6. CHECK THE (B20) BRAKE FLUID LEVEL SWITCH SENSE CIRCUIT FOR AN OPEN
1. Turn the ignition off.
2. Measure the resistance of the (B20) Brake Fluid Level Switch Sense circuit between the Brake Fluid Level Switch harness connector and the BCM harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 7

No

- Repair the open in the (B20) Brake Fluid Level Switch Sense circuit.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

7. CHECK THE (Z420) BRAKE FLUID LEVEL SWITCH GROUND CIRCUIT FOR AN OPEN
1. Turn the ignition off.
2. Measure the resistance of the (B20) Brake Fluid Level Switch Ground circuit between the Brake Fluid Level Switch harness connector and the BCM harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 8

No

- Repair the open in the (B20) Brake Fluid Level Switch Ground circuit.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

8. CHECK THE BCM FOR CORRECT OPERATION
1. Connect a jumper wire between the (B20) Brake Fluid Level Switch Sense circuit and the (Z901) Ground circuit in the Brake Fluid Level Switch harness connector.
2. Turn the ignition on.
3. With the scan tool, read the Brake Fluid Level Voltage.

Is the voltage below 1.0 volt?

Yes

- Replace the Brake Fluid Level Switch. Brake Fluid Level Switch - Removal.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

No

- Replace the Body Control Module (BCM).
- Perform the ABS VERIFICATION TEST. ABS Verification Test.