DTC B10B4 or B120C

Diagnostic Instructions Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach. Diagnostic Procedure Instructions provides an overview of each diagnostic category. DTC Descriptors DTC B10B4 Left Front Discriminating Sensor Signal DTC B120C Right Front Discriminating Sensor Signal Diagnostic Fault Information

Circuit	Circuit Function	Short to Ground	Open/Sho to Voltage	rt Invalid Serial Data	Signal Performan
354	Signal	B10B4 11	B10B4 15	B10B4 81	-
5045	Low Reference	B10B4 11	B10B4 15	B10B4 81	-
1409	Signal	B120C 11	B120C 15	B120C 81	-
5600	Low Refrence	B120C 11	B120C 15	B120C 81	-

Circuit/System Description For an overview of the component/system, refer to: Supplemental Inflatable Restraint System Description and Operation The B58L Airbag Front End Discriminating Sensor - Left, and B58R Airbag Front End Discriminating Sensor - Right, are sensors that detect acceleration and provide input to the K36  Restraints Control Module. The K36 Restraints Control Module monitors the inputs given by several sensors and when a collision is detected, the control module will trigger certain airbags and seat belt pretensioners, depending on the angle and severity of the impact. The B58 Front Impact Sensors are generally located on the radiator core support. The B58L Airbag Front End Discriminating Sensor - Left, uses circuit 354 as the signal circuit and circuit 5045 as the low reference circuit. B58R Airbag Front End Discriminating Sensor - Right, uses circuit 1409 as the signal circuit and circuit 5600 as the low reference circuit. The signal circuit on both impact sensors is the control module input and has an internal resistance connected to 5 V. The low reference circuit is grounded through the control module. Conditions for Running the DTC Ignition voltage is between 9–16 V. Conditions for Setting the DTC Any of the following conditions exist for 10 seconds: B10B4 11 The sensor has been shorted to ground. The sensor current is greater than 23 mA for greater than 5 ms. B120C 11 The sensor has been shorted to ground. The sensor current is greater than 23 mA for greater than 5 ms. B10B4 15 The sensor circuit is open or short to voltage. The Restraints Control Module has not received a message from the sensor for greater than 375 milliseconds. B120C 15 The sensor circuit is open or short to voltage. The Restraints Control Module has not received a message from the sensor for greater than 375 milliseconds. B10B4 81 The Restraints Control Module has received invalid serial data from the sensor. B120C 81 The Restraints Control Module has received invalid serial data from the sensor. Action Taken When the DTC Sets The Restraints Control Module requests the instrument cluster to illuminate the airbag indicator. Conditions for Clearing the DTC The condition for setting the DTC no longer exists. A history DTC will clear once 100 malfunction-free ignition cycles have occurred. An ignition cycle is required for the DTC to go from current to history. 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. Check the circuit terminals for fretting or incorrectly seated connector if a DTC with symptom byte 1B is set. Reference Information Schematic Reference SIR Schematics Connector End View Reference Master Electrical Component List Description and Operation Supplemental Inflatable Restraint System Description and Operation Electrical Information Reference Circuit Testing Testing for Intermittent Conditions and Poor Connections Connector Repairs Wiring Repairs Scan Tool Reference Control Module References for scan tool information Circuit/System Verification

Note

The condition may be intermittent and require driving the vehicle, then reviewing the snapshot to verify resistance parameters do not drop out or spike. Refer to Testing for Intermittent Conditions and Poor Connections

1. Ignition ON.
2. Verify that DTC B10B4 or B120C symptom byte 81 is not set as current. ⇒ If DTC B10B4 or B120C symptom byte 81 is set as current Replace the appropriate B58 Front Impact Sensor. ⇓ If DTC B10B4 or B120C symptom byte 81 is not set as current
3. Verify that DTC B10B4 or B120C symptom byte 11 or 15 is not set as current. ⇒ If DTC B10B4 or B120C symptom byte 11 or 15 is set as current Refer to Circuit/System Testing. ⇓ If DTC B10B4 or B120C symptom byte 11 or 15 is not set as current
4. 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 all terminals for damage or corrosion when disconnecting connectors. Damage or corrosion in the following requires repair or replacement of the affected component/connector. – Impact sensor – Restraints Control Module – Impact sensor wiring harness connector – Restraints Control Module wiring 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 OFF. It may take up to 2 min for all vehicle systems to power down.
2. Verify the SIR system is disabled.
3. Disconnect the harness connector at the appropriate B58 Front Impact Sensor.
4. Test for less than 10 Ω between the low reference circuit terminal 2 and ground. ⇒ If 10 Ω or greater 4.1. Disconnect the appropriate harness connector at the K36 Restraints Control Module. 4.2. Test for less than 2 Ω in the low reference circuit end to end. ⇒ If 2 Ω or greater, repair the open/high resistance in the circuit. ⇒ If less than 2 Ω, replace the K36 Restraints Control Module. ⇓ If less than 10 Ω
5. Test for greater than 50k Ω between the signal circuit terminal 1 and ground. ⇒ If 50k Ω or less 5.1. Test the following circuits for a short to ground. DTC B10B4 = Circuit 354 DTC B120C = Circuit 1409 ⇒ If less than infinite resistance, repair the short to ground on the circuit. ⇒ If infinite resistance, replace the K36 Restraints Control Module. ⇓ If greater than 50k Ω
6. Ignition ON,
7. Verify the SIR system is disabled.
8. Test for less than 1 V between the signal circuit terminal 1 and ground. ⇒ If 1 V or greater 8.1. Ignition OFF, disconnect the harness connector at the K36 Restraints Control Module, ignition ON. 8.2. Test between the following circuits for short to voltage: DTC B10B4 = Circuit 354, and Circuit 5045 DTC B120C = Circuit 1409, and Circuit 5600 ⇒ If greater than 1 V, repair the short to voltage on the circuit. ⇒ If less than 1 V, replace the K36 Restraints Control Module. ⇓ If less than 1 V

Note

When using the MIN MAX function, autorange on the DMM may not function properly. To ensure accurate test results, turn off autorange and manually set the DMM range to 000.0 V.

9. Ignition OFF.
10. Verify the SIR system is disabled.
11. Install a DMM between the signal circuit terminal 1 and ground. Set the DMM to capture DC voltage using the MIN MAX function. Turn off autorange and manually set the DMM range to 000.0 V. Ignition ON.
12. Verify the MAX voltage captured by the DMM is between 4–9V. ⇒ If less than 4 V 12.1. Verify the SIR system is disabled. 12.2. Disconnect the appropriate harness connector at the K36 Restraints Control Module. 12.3. Test between the following circuits for short to ground: DTC B10B4 = Circuit 354, and Circuit 5045 DTC B120C = Circuit 1409, and Circuit 5600 ⇒ If less than infinite resistance, repair the short to ground on the circuit. ⇓ If infinite resistance 12.4. Test the following circuits for open/high resistance: DTC B10B4 = Circuit 354 DTC B120C = Circuit 1409 ⇒ If 2 Ω or greater, repair the open/high resistance in the circuit. ⇒ If less than 2 Ω, replace the Restraints Control Module. ⇒ If greater than 9V 12.1. Ignition OFF. Disconnect the appropriate harness connector at the K36 Restraints Control Module. Ignition ON. 12.2. Test for short to voltage between ground and the following circuits: DTC B10B4 = Circuit 354 DTC B120C = Circuit 1409 ⇒ If 1 V or greater, repair the short to voltage on the circuit. ⇒ If less than 1 V, replace the K36 Restraints Control Module. ⇓ If between 4–9V
13. Ignition OFF, connect all harness connectors, press in the CPA (if equipped) until an audible and/or tactile click is heard.
14. Ignition ON, clear DTCs. Operate the vehicle within the Conditions for Running the DTC.
15. Verify DTC B10B4 or B120C is not set. ⇒ If the DTC sets 15.1. Replace the B58 Front Impact Sensor. 15.2. Verify the DTC does not set. ⇒ If the DTC sets, replace the K36 Restraints Control Module. ⇓ If the DTC does not set. 15.3. All OK. ⇓ If the DTC does not set
16. A fault is not currently present and may be an intermittent condition. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Airbag Front End Discriminating Sensor Replacement Control Module References for Restraints Control Module control module replacement, programming and setup