2007 Liberty KJ Factory Service Manual 8 - ELECTRICAL

*BELT TENSION SENSOR / PRESSURE SENSOR FAULTS

For a complete wiring diagram Refer to Section 8W.



Possible Causes
 
OCS WIRING CHAFED, PIERCED, PINCHED, OR BROKEN
 
OCS WIRING CONNECTOR TERMINAL(S) BROKEN, BENT, PUSHED OUT, CORRODED, OR CONTAMINATED
 
PASSENGER BLADDER PRESSURE SENSOR POWER, SIGNAL, OR GROUND CIRCUIT OPEN
 
PASSENGER BLADDER PRESSURE SENSOR POWER, SIGNAL, OR GROUND CIRCUIT SHORTED TO VOLTAGE
 
PASSENGER BLADDER PRESSURE SENSOR POWER, SIGNAL, OR GROUND CIRCUIT SHORTED TO GROUND
 
SEAT BELT TENSION SENSOR POWER, SIGNAL, OR GROUND CIRCUIT OPEN
 
SEAT BELT TENSION SENSOR POWER, SIGNAL, OR GROUND CIRCUIT SHORTED TO VOLTAGE
 
SEAT BELT TENSION SENSOR POWER, SIGNAL, OR GROUND CIRCUIT SHORTED TO GROUND
 
BELT TENSION SENSOR
 
PASSENGER SEAT WEIGHT SENSOR
 
OCM
 




Diagnostic Test

1. INSPECT THE OCCUPANT CLASSIFICATION SYSTEM (OCS) WIRING AND CONNECTORS FOR CONDITIONS THAT CAUSED THE DTC(s) TO SET

Turn the ignition on.
With the scan tool, record and erase Occupant Classification Module (OCM) DTCs.

WARNING: To avoid personal injury or death, turn the ignition off, disconnect the battery and wait two minutes before proceeding.


Using the wiring diagram/schematic as a guide, inspect Occupant Classification System (OCS) wiring and connectors for chafed, pierced, pinched, and partially broken wires, and for broken, bent, pushed out, corroded, and contaminated terminals.

Are any of these conditions present?

Yes


No

2. CHECK FOR ACTIVE OCM DTCs

Reconnect all disconnected OCS harness connectors.

WARNING: To avoid personal injury or death, turn the ignition on, then reconnect the battery.


With the scan tool, select OCM. Wait two minutes before proceeding.
With the scan tool, read active OCM DTCs.

Does the scan tool display any active Belt Tension Sensor or Pressure Sensor Related DTCs?

Yes


No, But Other DTCs Active


No DTCs Active

3. CHECK THE VOLTAGE OF THE PASSENGER BLADDER PRESSURE SENSOR POWER, SIGNAL, AND GROUND CIRCUIT

WARNING: To avoid personal injury or death, turn the ignition off, disconnect the battery and wait two minutes before proceeding.


Disconnect the Passenger Seat Weight Sensor.
Disconnect the Belt Tension Sensor.

WARNING: To avoid personal injury or death, turn the ignition on, then reconnect the battery.


Measure the voltage of the Passenger Bladder Pressure Sensor Power circuit. The voltage should be approximately 4.9 volts.
Measure the voltage of the Passenger Bladder Pressure Sensor Signal circuit. The voltage should be approximately 2.5 volts.
Measure the voltage of the Passenger Bladder Pressure Sensor Ground circuit. The voltage should be 0.0 volts.

Is the voltage correct on all three circuits?

Yes


No

4. CHECK THE VOLTAGE BETWEEN THE PASSENGER BLADDER PRESSURE SENSOR POWER AND GROUND CIRCUIT

Measure the voltage between the Passenger Bladder Pressure Sensor Power circuit and the Passenger Bladder Pressure Sensor Ground circuit. The voltage should be approximately 4.9 volts.

Is the voltage correct?

Yes


No

5. CHECK THE VOLTAGE OF THE SEAT BELT TENSION SENSOR POWER, SIGNAL, AND GROUND CIRCUIT

Measure the voltage of the Seat Belt Tension Sensor Power circuit. The voltage should be approximately 4.9 volts.
Measure the voltage of the Seat Belt Tension Sensor Signal circuit. The voltage should be approximately 2.5 volts.
Measure the voltage of the Seat Belt Tension Sensor Ground circuit. The voltage should be 0.0 volts.

Is the voltage correct on all three circuits?

Yes


No

6. CHECK THE VOLTAGE BETWEEN THE SEAT BELT TENSION SENSOR POWER AND GROUND CIRCUIT

Measure the voltage between the Seat Belt Tension Sensor Power circuit and the Seat Belt Tension Sensor Ground circuit. The voltage should be approximately 4.9 volts.

Is the voltage correct?

Yes


No

7. CHECK THE VOLTAGE OF THE PASSENGER BLADDER PRESSURE SENSOR POWER, SIGNAL, AND GROUND CIRCUIT WITH THE BELT TENSION SENSOR CONNECTED

WARNING: To avoid personal injury or death, turn the ignition off, disconnect the battery and wait two minutes before proceeding.


Connect the Belt Tension Sensor.

WARNING: To avoid personal injury or death, turn the ignition on, then reconnect the battery.


Measure the voltage of the Passenger Bladder Pressure Sensor Power circuit. The voltage should be approximately 4.9 volts.
Measure the voltage of the Passenger Bladder Pressure Sensor Signal circuit. The voltage should be approximately 2.5 volts.
Measure the voltage of the Passenger Bladder Pressure Sensor Ground circuit. The voltage should be 0.0 volts.

Is the voltage correct on all three circuits?

Yes


No

8. CHECK THE VOLTAGE OF THE SEAT BELT TENSION SENSOR POWER, SIGNAL, AND GROUND CIRCUIT WITH THE PASSENGER SEAT WEIGHT SENSOR CONNECTED

WARNING: To avoid personal injury or death, turn the ignition off, disconnect the battery and wait two minutes before proceeding.


Disconnect the Belt Tension Sensor.
Connect the Passenger Seat Weight Sensor.

WARNING: To avoid personal injury or death, turn the ignition on, then reconnect the battery.


Measure the voltage of the Seat Belt Tension Sensor Power circuit. The voltage should be approximately 4.9 volts.
Measure the voltage of the Seat Belt Tension Sensor Signal circuit. The voltage should be approximately 2.5 volts.
Measure the voltage of the Seat Belt Tension Sensor Ground circuit. The voltage should be 0.0 volts.

Is the voltage correct on all three circuits?

Yes


No

9. CHECK FOR AN OPEN PASSENGER SEAT WEIGHT SENSOR

WARNING: To avoid personal injury or death, turn the ignition off, disconnect the battery and wait two minutes before proceeding.


Disconnect the OCM harness connector.
Measure the resistance between the Passenger Bladder Pressure Sensor Power circuit and the Passenger Bladder Pressure Sensor Ground circuit in the OCM harness connector.

NOTE: Verify that the DVOM is connected with the positive lead to the Power circuit and the negative lead to the Ground circuit.



Is the resistance approximately 3.25k ohms?

Yes


No

10. CHECK FOR AN OPEN PASSENGER SEAT WEIGHT SENSOR

Measure the resistance between the Passenger Bladder Pressure Sensor Signal circuit and the Passenger Bladder Pressure Sensor Ground circuit in the OCM harness connector.

NOTE: Verify that the DVOM is connected with the positive lead to the Signal circuit and the negative lead to the Ground circuit.



Is the resistance approximately 106k ohms?

Yes


No

11. CHECK FOR AN OPEN SEAT BELT TENSION SENSOR

Connect the Belt Tension Sensor.
Measure the resistance between the Seat Belt Tension Sensor Power circuit and the Seat Belt Tension Sensor Ground circuit in the OCM harness connector.

NOTE: Verify that the DVOM is connected with the positive lead to the Power circuit and the negative lead to the Ground circuit.



Is the resistance approximately 7.5k ohms?

Yes


No

12. CHECK FOR AN OPEN SEAT BELT TENSION SENSOR

Measure the resistance between the Seat Belt Tension Sensor Signal circuit and the Seat Belt Tension Sensor Ground circuit in the OCM harness connector.

NOTE: Verify that the DVOM is connected with the positive lead to the Signal circuit and the negative lead to the Ground circuit.



Is the resistance approximately 19.5m ohms?

Yes


No

13. CHECK THE PASSENGER BLADDER PRESSURE SENSOR AND THE SEAT BELT TENSION SENSOR POWER, SIGNAL, AND GROUND CIRCUIT FOR A SHORT TO VOLTAGE

WARNING: To avoid personal injury or death, turn the ignition off, disconnect the battery and wait two minutes before proceeding.


Disconnect the OCM harness connector.

WARNING: To avoid personal injury or death, turn the ignition on, then reconnect the battery.


Measure the voltage of the Passenger Bladder Pressure Sensor Power circuit.
Measure the voltage of the Passenger Bladder Pressure Sensor Signal circuit.
Measure the voltage of the Passenger Bladder Pressure Sensor Ground circuit.
Measure the voltage of the Seat Belt Tension Sensor Power circuit.
Measure the voltage of the Seat Belt Tension Sensor Signal circuit.
Measure the voltage of the Seat Belt Tension Sensor Ground circuit.

Is there any voltage present on any of the circuits?

Yes


No

14. CHECK THE PASSENGER BLADDER PRESSURE SENSOR POWER CIRCUIT FOR AN OPEN

WARNING: To avoid personal injury or death, turn the ignition off, disconnect the battery and wait two minutes before proceeding.


Measure the resistance of the Passenger Bladder Pressure Sensor Power circuit between the OCM connector and the Passenger Seat Weight Sensor connector.

Is the resistance below 5.0 ohms?

Yes


No

15. CHECK THE PASSENGER BLADDER PRESSURE SENSOR SIGNAL CIRCUIT FOR AN OPEN

Measure the resistance of the Passenger Bladder Pressure Sensor Signal circuit between the OCM connector and the Passenger Seat Weight Sensor connector.

Is the resistance below 5.0 ohms?

Yes


No

16. CHECK THE SEAT BELT TENSION SENSOR POWER CIRCUIT FOR AN OPEN

Measure the resistance of the Seat Belt Tension Sensor Power circuit between the OCM connector and the Belt Tension Sensor connector.

Is the resistance below 5.0 ohms?

Yes


No

17. CHECK THE SEAT BELT TENSION SENSOR SIGNAL CIRCUIT FOR AN OPEN

Measure the resistance of the Seat Belt Tension Sensor Signal circuit between the OCM connector and the Belt Tension Sensor connector.

Is the resistance below 5.0 ohms?

Yes


No

18. CHECK THE PASSENGER BLADDER PRESSURE SENSOR AND THE SEAT BELT TENSION SENSOR POWER, SIGNAL, AND GROUND CIRCUIT FOR A SHORT TO GROUND

Measure the resistance between ground and the Passenger Bladder Pressure Sensor Power circuit.
Measure the resistance between ground and the Passenger Bladder Pressure Sensor Signal circuit.
Measure the resistance between ground and the Passenger Bladder Pressure Sensor Ground circuit.
Measure the resistance between ground and the Seat Belt Tension Sensor Power circuit.
Measure the resistance between ground and the Seat Belt Tension Sensor Signal circuit.
Measure the resistance between ground and the Seat Belt Tension Sensor Ground circuit.

Is the resistance below 10k ohms on any of the circuits?

Yes


No

19. CHECK THE PASSENGER BLADDER PRESSURE SENSOR POWER CIRCUIT FOR A SHORT TO THE OTHER SENSOR CIRCUITS

Measure the resistance between the Passenger Bladder Pressure Sensor Power circuit and the Passenger Bladder Pressure Sensor Signal circuit.
Measure the resistance between the Passenger Bladder Pressure Sensor Power circuit and the Passenger Bladder Pressure Sensor Ground circuit.
Measure the resistance between the Passenger Bladder Pressure Sensor Power circuit and the Seat Belt Tension Sensor Power circuit.
Measure the resistance between the Passenger Bladder Pressure Sensor Power circuit and the Seat Belt Tension Sensor Signal circuit.
Measure the resistance between the Passenger Bladder Pressure Sensor Power circuit and the Seat Belt Tension Sensor Ground circuit.

Is the resistance below 10k ohms on any of the circuits?

Yes


No

20. CHECK THE PASSENGER BLADDER PRESSURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO THE OTHER SENSOR CIRCUITS

Measure the resistance between the Passenger Bladder Pressure Sensor Signal circuit and the Passenger Bladder Pressure Sensor Ground circuit.
Measure the resistance between the Passenger Bladder Pressure Sensor Signal circuit and the Seat Belt Tension Sensor Power circuit.
Measure the resistance between the Passenger Bladder Pressure Sensor Signal circuit and the Seat Belt Tension Sensor Signal circuit.
Measure the resistance between the Passenger Bladder Pressure Sensor Signal circuit and the Seat Belt Tension Sensor Ground circuit.

Is the resistance below 10k ohms on any of the circuits?

Yes


No

21. CHECK THE PASSENGER BLADDER PRESSURE SENSOR GROUND CIRCUIT FOR A SHORT TO THE OTHER SENSOR CIRCUITS

Measure the resistance between the Passenger Bladder Pressure Sensor Ground circuit and the Seat Belt Tension Sensor Power circuit.
Measure the resistance between the Passenger Bladder Pressure Sensor Ground circuit and the Seat Belt Tension Sensor Signal circuit.
Measure the resistance between the Passenger Bladder Pressure Sensor Ground circuit and the Seat Belt Tension Sensor Ground circuit.

Is the resistance below 10k ohms on any of the circuits?

Yes


No

22. CHECK THE SEAT BELT TENSION SENSOR POWER CIRCUIT FOR A SHORT TO THE OTHER SENSOR CIRCUITS

Measure the resistance between the Seat Belt Tension Sensor Power circuit and the Seat Belt Tension Sensor Signal circuit.
Measure the resistance between the Seat Belt Tension Sensor Power circuit and the Seat Belt Tension Sensor Ground circuit.

Is the resistance below 10k ohms on any of the circuits?

Yes


No

23. CHECK THE SEAT BELT TENSION SENSOR SIGNAL CIRCUIT FOR A SHORT TO THE SEAT BELT TENSION SENSOR GROUND CIRCUIT

Measure the resistance between the Seat Belt Tension Sensor Signal circuit and the Seat Belt Tension Sensor Ground circuit.

Is the resistance below 10k ohms?

Yes


No

24. CHECK FOR AN OPEN PASSENGER BLADDER PRESSURE SENSOR GROUND CIRCUIT

WARNING: To avoid personal injury or death, turn the ignition off, disconnect the battery and wait two minutes before proceeding.


Disconnect the OCM harness connector.
Measure the resistance of the Passenger Bladder Pressure Sensor Ground circuit between the Passenger Seat Weight Sensor harness connector and the OCM harness connector.

Is the resistance below 5.0 ohms?

Yes


No

25. CHECK FOR AN OPEN SEAT BELT TENSION SENSOR GROUND CIRCUIT

WARNING: To avoid personal injury or death, turn the ignition off, disconnect the battery and wait two minutes before proceeding.


Disconnect the OCM harness connector.
Measure the resistance of the Seat Belt Tension Sensor Ground circuit between the Belt Tension Sensor harness connector and the OCM harness connector.

Is the resistance below 5.0 ohms?

Yes


No

26. DETERMINE THE CORRECT REPAIR

NOTE: The Occupant Classification Module (OCM) and the Passenger Seat Bladder and Cushion Kit are the only serviceable OCS components.


Determine the correct repair by verifying if the front passenger seat has a Bladder and Cushion Service Kit as follows:

Does the seat have a Bladder and Cushion Service Kit?

Yes


No