BAS Travel Sensor Circuit

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 Brake Assist System (BAS) Circuit Diagram refer to Diagrams; Electrical
Diagnostic Test
1. MEASURE THE VOLTAGE OF THE BAS TRAVEL SENSOR SIGNAL CIRCUIT
Turn the ignition off.
Disconnect the BAS Brake Booster 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 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 harness connector.
Is the resistance below 5.0 ohms?
Yes >> Repair the BAS Travel Sensor Signal circuit for a short to the 5-Volt Supply circuit. Perform ABS VERIFICATION TEST.
No >> Go to 3

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 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.

4. MEASURE THE RESISTANCE BETWEEN GROUND AND THE BAS TRAVEL SENSOR GROUND CIRCUIT
With the ignition off.





Measure the resistance between ground and the BAS Travel Sensor Ground circuit.
Is the resistance below 100 ohms?
Yes >> Repair the BAS Travel Sensor Ground circuit for a short to ground. Perform ABS VERIFICATION TEST.
No >> Go to 5

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 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 below 100 ohms?
Yes >> Repair the BAS Travel Sensor Signal circuit for a short to ground. Perform ABS VERIFICATION TEST.
No >> Go to 7

7. MEASURE THE RESISTANCE BETWEEN THE BAS TRAVEL SENSOR SIGNAL CIRCUIT AND THE GROUND CIRCUIT
With the ignition off.





Measure the resistance between the BAS Travel Sensor Signal circuit and the BAS Travel Sensor Ground circuit in the BAS Brake Booster harness connector.
Is the resistance below 100 ohms?
Yes >> Repair the BAS Travel Sensor Signal circuit for a short to the BAS Travel Sensor Ground circuit. Perform ABS VERIFICATION TEST.
No >> Replace the BAS Brake Booster. Perform ABS VERIFICATION TEST.

8. 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 below 100 ohms?
Yes >> Repair the 5-Volt Supply circuit for a short to ground. Perform ABS VERIFICATION TEST.
No >> Go to 9

9. 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 harness connector to the CAB harness connector.
Is the resistance below 5.0 ohms?
Yes >> Replace the Controller Antilock Brake. Perform ABS VERIFICATION TEST.
No >> Repair the BAS Travel Sensor 5-Volt Supply circuit for an open. Perform ABS VERIFICATION TEST.