DTC B1491

Diagnostic Instructions Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions DTC Descriptor Co-Driver Automatic Locking Retractor Switch Signal Symptom Byte Information: Symptom Byte List Diagnostic Fault Information

Circuit	Circuit Function	Short to Ground	Circuit Voltage Below Thresho	Circuit Voltage Above ldThreshol	Open Circuit d	Circuit Voltage Out of Range	Signal Perform
3947	Signal	B1491 11	B1491 16	B1491 17	B1491 13	B1491 1C	B1491 64
3946	Low Reference	B1491 11	B1491 16	B1491 17	B1491 13	B1491 1C	B1491 64

Circuit/System Description For an overview of the component/system, refer to: Supplemental Inflatable Restraint System Description and Operation The B61P Seat Belt Tension Sensor — Passenger is a 2–wire hall effect current sensor and mounted on the passenger seat belt retractor to measure the seat belt tension. If the shoulder portion of a passenger seat belt is fully extended, the infant car seat restraint locking feature may be engaged, disabling the passenger Airbag. The B61P Seat Belt Tension Sensor — Passenger uses circuit 3947 as the signal circuit, and circuit 3946 as the low reference circuit. The signal circuit has an internal resistance connected to 5 V and the low reference circuit is grounded through the K85P Restraint Occupant Classification System Module - Passenger. Conditions for Running the DTC Ignition ON Ignition Voltage = 9 to 16 V Conditions for Setting the DTC Passenger seat Belt tension Sensor — Signal circuit = Less than .5 V or Greater than 4.5 V Passenger Seat Belt Tension Sensor — Low Reference circuit = Greater than 25 mA The above condition(s) must occur for greater than 1 s Actions Taken When the DTC Sets System State may be disabled depending on certain conditions Conditions for Clearing the DTC A current DTC will clear when the diagnostic runs and passes. A history DTC will clear after 100 consecutive malfunction-free ignition cycles Diagnostic Aid

Note

The following diagnostic aids apply for both current and history DTCs. Refer to SIR Disabling and Enabling. Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in a misdiagnosis, causing a part replacement with a reappearance of the malfunction. If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections. An incorrectly seated connector can cause an open/high resistance condition. Reference Information Schematic Reference SIR Schematics Connector End View Reference Master Electrical Component List Description and Operation For an overview of the component/system, refer to: Supplemental Inflatable Restraint System Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Scan Tool Reference Control Module References Circuit/System Verification

Note

The condition may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections

1. Ignition ON / Vehicle In Service Mode.
2. Verify that DTC B1491 is not set as current. ⇒ If DTC B1491 is set as current Refer to Circuit/System Testing. ⇓ If DTC B1491 is not set as current
3. A fault is not currently present and may be an intermittent condition. Circuit/System Testing

Note

Refer to SIR Service Precautions. Refer to SIR Disabling and Enabling. inspect the terminals of the following components and connectors for damage or corrosion and repair or replace as necessary: B61P Seat Belt Tension Sensor - Passenger K85P Restraint Occupant Classification System Module - Passenger Inline Harness Connector The connector and connector position assurance (CPA) may seat independent of each other. Both the connector and CPA should seat with an audible and/or tactile click.

1. Ignition/Vehicle & All vehicle systems OFF
2. Disconnect the harness connector at the B61P Seat Belt Tension Sensor - Passenger
3. Test for less than 10 Ω between low reference circuit terminal 1 and ground ⇒ If 10 Ω or greater 3.1. Test circuit 3946 for an open. ⇒ If an open circuit is found, repair the fault on the circuit. ⇓ If an open circuit is not found 3.2. Replace the K85P Restraints Occupant Classification System Control Module ⇓ If less than 10 Ω
4. Ignition On / Vehicle In Service Mode
5. Test for less than 6 V between the test points: Signal circuit terminal 2 and Ground. ⇒ If 6 V or greater 5.1. Ignition/Vehicle & All vehicle systems OFF 5.2. Disconnect the electrical connector K85P Restraint Occupant Classification System Module - Passenger 5.3. Ignition ON / Vehicle In Service Mode 5.4. Test Circuit 3947 for short to voltage ⇒ If short to voltage is found, repair the fault on the circuit. ⇓ If short to voltage is not found 5.5. Replace K85P Restraint Occupant Classification System Module — Passenger ⇓ If less than 6 V
6. Ignition/Vehicle & All vehicle systems OFF
7. Test for greater than 5 kΩ between the test points: Signal circuit terminal 2 and Ground ⇒ If 5 kΩ or less 7.1. Disconnect the K85P Restraint Occupant Classification System Module — Passenger 7.2. Test circuit 3947 for short to ground ⇒ If short to ground found, repair the fault on the circuit ⇓ If infinite resistance 7.3. Replace the K85P Restraint Occupant Classification System Module - Passenger ⇓ If Greater than 5 kΩ
8. Disconnect the K85P Restraint Occupant Classification System Module - Passenger
9. Test for less than 2 Ω between the test points: Signal circuit terminal 2 at B61P Seat Belt Tension Sensor - Passenger and The other end of the circuit at Control module harness ⇒ If 2 Ω or greater Repair the open/high resistance in the circuit. ⇓ If less than 2 Ω
10. If all conditions test normal = Replace the B61P Seat Belt Tension Sensor - Passenger
11. Operate the vehicle within the Conditions for Running the DTC
12. Verify the DTC B1491 is not set. ⇒ If the DTC is set Replace the K85P Restraint Occupant Classification System Module - Passenger ⇓ If the DTC is not set
13. A fault is not currently present and may be an intermittent condition. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Front Seat Belt Retractor Replacement — B61P Seat Belt Tension Sensor - Passenger SIR/SRS Wiring Repairs For control module replacement, programming, and setup refer to Control Module References