B1B79

B1B79-PASSENGER SEAT WEIGHT SENSOR 3 - LEFT FRONT INPUT CIRCUIT LOW

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

- When Monitored:
While the CAN bus ignition status is in IGN_RUN, the Occupant Classification Module (OCM) checks the sensor input ranges.

- Set Condition:
If the OCM detects that the sensor input is less than 3.4 ±.6% of the (R701) Seat Weight Sensor 5-volt circuit voltage. This DTC will also set if the (R701) Seat Weight Sensor 5-volt circuit is shorted to ground. However, this condition would prevent communication with the OCM and cause a Lost Communication With OCM DTC to set in other modules. Also, this DTC will remain active after the condition that set this fault is no longer present. This condition is referred to as latching the DTC for the ignition cycle. Cycling the ignition key will change the status from active to stored if the condition that set the fault is no longer present.

1. CHECK FOR ACTIVE INTERNAL FAULTS, IGNITION FAULTS, AND BATTERY FAULTS IN THE OCCUPANT CLASSIFICATION MODULE (OCM)

NOTE: Make sure that the battery is fully charged.

1. Turn the ignition on, then off, and then on again.
2. With the scan tool, read Occupant Classification Module (OCM) DTCs.

Does the scan tool display any active DTCs relating to internal faults, ignition faults, or battery faults?

Yes

- Diagnose and repair the DTC. Testing and Inspection for a complete list of DTCs.

No

- Go To 2

2. VERIFY THAT DTC B1B79-PASSENGER SEAT WEIGHT SENSOR 3 - LEFT FRONT INPUT CIRCUIT LOW IS ACTIVE
1. With the scan tool, read the OCM DTCs.

Does the scan tool display active B1B79-PASSENGER SEAT WEIGHT SENSOR 3 - LEFT FRONT INPUT CIRCUIT LOW DTC?

Yes

- Go To 3

No

- Perform the OCS INTERMITTENT TEST. . OCS Intermittent Test

3. VERIFY THAT B1B7A-PASSENGER SEAT WEIGHT SENSOR 3 - LEFT FRONT INPUT CIRCUIT HIGH DTC AND B1B79-PASSENGER SEAT WEIGHT SENSOR 3 - LEFT FRONT INPUT CIRCUIT LOW DTC ARE ACTIVE AT THE SAME TIME
1. With the scan tool, read the OCM DTCs.

Does the scan tool display active B1B7A-PASSENGER SEAT WEIGHT SENSOR 3 - LEFT FRONT INPUT CIRCUIT HIGH AND B1B79-PASSENGER SEAT WEIGHT SENSOR 3 - LEFT FRONT INPUT CIRCUIT LOW DTC AT THE SAME TIME?

Yes

- Perform the B1B79-PASSENGER SEAT WEIGHT SENSOR 3 - LEFT FRONT INPUT CIRCUIT HIGH diagnostic procedure.
No

- Go To 4

4. INSPECT PASSENGER SEAT HARNESS WIRES AND CONNECTORS

WARNING: Turn the ignition off, disconnect the 12-volt battery and wait two minutes before proceeding. Failure to follow these instructions may result in possible serious or fatal injury.

1. Using the wiring diagram / schematic as a guide, inspect the Passenger Seat Harness wiring and connectors. Look for chafed, pierced, pinched, or partially broken wires and broken, bent, pushed out, spread, corroded, or contaminated terminals.

NOTE: Do not attempt to repair the Seat Harness. Replace the Seat Harness if the condition inspecting or testing for is present in the Seat Harness.

Are any of these conditions present?

Yes

- Replace the Passenger Seat Harness.
- Perform the RE-ZERO OCM SEAT WEIGHT SENSORS diagnostic procedure. . Re-Zero OCM Seat Weight Sensors

No

- Go To 5

5. VERIFY THAT PASSENGER SEAT HARNESS IS ROUTED CORRECTLY
1. Verify that the Passenger Seat Harness is routed correctly.

Is the Passenger Seat Harness routed correctly?

Yes

- Go To 6

No

- Reroute the Passenger Seat Harness as necessary.
- Perform the RE-ZERO OCM SEAT WEIGHT SENSORS diagnostic procedure. . Re-Zero OCM Seat Weight Sensors

6. CHECK VOLTAGE OF (R701) SEAT WEIGHT SENSOR 5-VOLT CIRCUIT

1. Disconnect the Left-Front Seat Weight Sensor connector.

WARNING: Turn the ignition on, then reconnect the 12-volt battery. Wait two minutes before proceeding. Failure to follow these instructions may result in possible serious or fatal injury.

2. Measure the voltage of the (R701) Seat Weight Sensor 5-volt circuit.

Is the voltage above 4.8 volts?

Yes

- Go To 7

No

- Go To 9

7. CHECK (R717) LT-FT SEAT WEIGHT SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND

1. Measure the resistance of the (R717) LT-FT Seat Weight Sensor Signal circuit between the OCM C2 connector and the Left-Front Seat Weight Sensor connector.

NOTE: Do not attempt to repair the Seat Harness. Replace the Seat Harness if the condition inspecting or testing for is present in the Seat Harness.

Is the resistance below 5.0 Ohms?

Yes

- Replace the Left-Front Seat Weight Sensor.
- Perform the RE-ZERO OCM SEAT WEIGHT SENSORS diagnostic procedure. . Re-Zero OCM Seat Weight Sensors
- If DTC B1B79-PASSENGER SEAT WEIGHT SENSOR 3 - LEFT FRONT INPUT CIRCUIT LOW returns active, Go To 10

No

- Replace the Passenger Seat Harness.
- Perform the RE-ZERO OCM SEAT WEIGHT SENSORS diagnostic procedure. . Re-Zero OCM Seat Weight Sensors

9. CHECK (R701) SEAT WEIGHT SENSOR 5-VOLT CIRCUIT FOR AN OPEN

WARNING: Turn the ignition off disconnect the 12-volt battery and wait two minutes before proceeding. Failure to follow these instructions may result in possible serious or fatal injury.

1. Disconnect the OCM connectors.
2. Measure the resistance of the (R701) Seat Weight Sensor 5-volt circuit between the OCM C2 connector and the Left-Front Seat Weight Sensor connector.

NOTE: Do not attempt to repair the Seat Harness. Replace the Seat Harness if the condition inspecting or testing for is present in the Seat Harness.

Is the resistance below 5.0 Ohms?

Yes

- WARNING: Turn the ignition off, disconnect the 12-volt battery and wait two minutes before proceeding. Failure to follow these instructions may result in possible serious or fatal injury.

- Replace the OCM.
- Perform the RE-ZERO OCM SEAT WEIGHT SENSORS diagnostic procedure. . Re-Zero OCM Seat Weight Sensors

No

- Replace the Passenger Seat Harness.
- Perform the RE-ZERO OCM SEAT WEIGHT SENSORS diagnostic procedure. . Re-Zero OCM Seat Weight Sensors

10. REPLACE THE OCCUPANT CLASSIFICATION MODULE

WARNING: Turn the ignition off, disconnect the 12-volt battery and wait two minutes before proceeding. Failure to follow these instructions may result in possible serious or fatal injury.

View repair

Repair

- WARNING: If the Occupant Classification Module (OCM) is dropped at any time, it must be replaced. Failure to take the proper precautions could result in accidental airbag deployment and may result in possible serious or fatal injury.

- Replace the OCM.
- Perform the RE-ZERO OCM SEAT WEIGHT SENSORS diagnostic procedure. . Re-Zero OCM Seat Weight Sensors