1000 - 1999: 1185

1185 - BAS TRAVEL SENSOR CIRCUIT





When Monitored and Set Condition

- When Monitored: Ignition on.
- Set Condition: The Controller Antilock Brake (CAB) detects a Brake Assist System (BAS) Travel Sensor malfunction.





For a complete Antilock Brake System (ABS) Circuit Diagram Brakes - ABS Electrical Diagnostics.

Diagnostic Test

1. MEASURE THE VOLTAGE OF THE BAS TRAVEL SENSOR SIGNAL CIRCUIT




Turn the ignition off.
Disconnect the BAS Brake Booster C1 harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Turn the ignition on.
Measure the voltage of the BAS Travel Sensor Signal circuit at the BAS Brake Booster C1 harness connector.
Is the voltage above 5.0 volts?

Yes

- Repair the BAS Travel Sensor Signal circuit for a short to voltage.
- Perform ABS VERIFICATION TEST. ABS Verification Test

No

- Go to 2

2. MEASURE THE RESISTANCE BETWEEN THE BAS TRAVEL SENSOR SIGNAL CIRCUIT AND THE 5-VOLT SUPPLY CIRCUIT




With the ignition off.
Disconnect the CAB harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between the BAS Travel Sensor Signal circuit and the 5-Volt supply circuit in the BAS Brake Booster C1 harness connector.
Is the resistance above 100k ohms?

Yes

- Go to 3

No

- Repair the BAS Travel Sensor Signal circuit for a short to the 5-Volt Supply circuit.
- Perform ABS VERIFICATION TEST. ABS Verification Test

3. MEASURE THE RESISTANCE OF THE BAS TRAVEL SENSOR SIGNAL CIRCUIT




With the ignition off.
Measure the resistance of the BAS Travel Sensor Signal circuit from the CAB harness connector to the BAS Brake Booster C1 harness connector.
Is the resistance below 5.0 ohms?

Yes

- Go to 4

No

- Repair the BAS Travel Sensor Signal circuit for an open.
- Perform ABS VERIFICATION TEST. ABS Verification Test

4. MEASURE THE RESISTANCE OF THE BAS TRAVEL SENSOR GROUND CIRCUIT




With the ignition off.
Measure the resistance of the BAS Travel Sensor Ground circuit from the CAB harness connector to the BAS Brake Booster C1 harness connector.
Is the resistance below 5.0 ohms?

Yes

- Go to 5

No

- Repair the BAS Travel Sensor Ground circuit for an open.
- Perform ABS VERIFICATION TEST. ABS Verification Test

5. MEASURE THE VOLTAGE OF THE 5-VOLT SUPPLY CIRCUIT




With the ignition off.
Reconnect the CAB harness connector.
Turn the ignition on.
Measure the voltage of the BAS Travel Sensor 5-Volt Supply circuit at the BAS Brake Booster C1 harness connector.
Is the voltage between 4.5 and 5.0 volts?

Yes

- Go to 6

No

- Go to 8

6. MEASURE THE RESISTANCE BETWEEN GROUND AND THE BAS TRAVEL SENSOR SIGNAL CIRCUIT




Turn the ignition off.
Disconnect the CAB harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between ground and the BAS Travel Sensor Signal circuit.
Is the resistance above 100k ohms?

Yes

- Go to 7

No

- Repair the BAS Travel Sensor Signal circuit for a short to ground.
- Perform ABS VERIFICATION TEST. ABS Verification Test

7. MEASURE THE RESISTANCE BETWEEN THE BAS TRAVEL SENSOR SIGNAL CIRCUIT AND THE SENSOR GROUND CIRCUIT




With the ignition off.
Measure the resistance between the BAS Travel Sensor Signal circuit and the BAS Travel Sensor Ground circuit at the BAS Brake Booster C1 harness connector.
Is the resistance above 100k ohms?

Yes

- Replace the BAS Brake Booster. Power Brake Booster - Removal.
- Perform ABS VERIFICATION TEST. ABS Verification Test

No

- Repair the BAS Travel Sensor Signal circuit for a short to the BAS Travel Sensor Ground circuit.
- Perform ABS VERIFICATION TEST. ABS Verification Test

8. CHECK THE BAS TRAVEL SENSOR 5-VOLT SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE




Turn the ignition off.
Disconnect the CAB harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Turn the ignition on.
Measure the voltage of the 5-Volt Supply circuit at the BAS Brake Booster C1 harness connector.
Is the voltage below 1.0 volt?

Yes

- Go to 9

No

- Repair the 5-Volt Supply circuit for a short to voltage.
- Perform ABS VERIFICATION TEST. ABS Verification Test

9. MEASURE THE RESISTANCE BETWEEN THE BAS TRAVEL SENSOR 5-VOLT SUPPLY CIRCUIT AND THE SENSOR GROUND CIRCUIT




Turn the ignition off.
Measure the resistance between the 5-Volt Supply circuit and the Sensor Ground circuit.
Is the resistance above 100k ohms?

Yes

- Go to 10

No

- Repair the 5-Volt Supply circuit for a short to the Sensor Ground circuit.
- Perform ABS VERIFICATION TEST. ABS Verification Test

10. MEASURE THE RESISTANCE BETWEEN GROUND AND THE BAS TRAVEL SENSOR 5-VOLT SUPPLY CIRCUIT




Turn the ignition off.
Disconnect the CAB harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between ground and the 5-Volt Supply circuit.
Is the resistance above 100k ohms?

Yes

- Go to 11

No

- Repair the 5-Volt Supply circuit for a short to ground.
- Perform ABS VERIFICATION TEST. ABS Verification Test

11. MEASURE THE RESISTANCE OF THE BAS TRAVEL SENSOR 5-VOLT SUPPLY CIRCUIT




With the ignition off.
Measure the resistance of the 5-Volt Supply circuit from the BAS Brake Booster C1 harness connector to the CAB harness connector.
Is the resistance below 5.0 ohms?

Yes

- Replace the Controller Antilock Brake (CAB) Module. Removal.
- Perform ABS VERIFICATION TEST. ABS Verification Test

No

- Repair the BAS Travel Sensor 5-Volt Supply circuit for an open.
- Perform ABS VERIFICATION TEST. ABS Verification Test