Pinpoint Test Bn: Second Row Left Side Airbag: Notes

Refer to appropriate Supplemental Restraint System in OEM Wiring Diagrams article, for schematic and connector information.

Normal Operation and Fault Conditions

The RCM continuously monitors the second row left side airbag circuits for the following faults:

Resistance out of range
Unexpected voltage
Short to ground
Faulted second row left side airbag
If a fault is detected, the RCM stores DTC B140A:11, B140A:12, B140A:13 or B140A:1A in memory and sends a message to the IPC to illuminate the airbag warning indicator.

The RCM analyzes the deployment loop resistance to determine if a fault exists. The value displayed in the PID is the deployment loop resistance measured by the RCM. If the value displayed is lower or higher than the desired range (refer to diagram below in illustration), the RCM can set a DTC. As the deployment loop resistance drifts farther outside the desired range, the chance for a DTC increases. Small variations in resistance can occur due to the effect of road vibrations on terminal fit. Crimps and terminals can be affected by stress and harness movement and can cause an increase in resistance due to wire strain. These variables can result in an intermittent fault. For this reason, the test requires the PID value to be within the desired range before the fault is considered repaired, regardless if the module is reporting an on-demand DTC at the time of diagnosis. Following this direction helps make sure that minor changes in resistance do not create a repeat concern. This test uses process of elimination to diagnose each part of the deployment loop circuit including:
Wiring
Connections
Second row left side airbag

PPT BN RCM DTC FAULT TRIGGER CONDITIONS

DTC

Description

Fault Trigger Conditions

Possible Causes

Wiring, terminals or connectors
Second row left side airbag
RCM

Visual Inspection and Diagnostic Pre-checks

Inspect for damaged wiring harness(es).
Inspect for loose or damaged connectors.

WARNING: Incorrect repair techniques or actions can cause an accidental SRS deployment. Never compromise or depart from these instructions. Failure to precisely follow all instructions could result in serious personal injury from an accidental deployment.

CAUTION: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may cause damage to the connector.

NOTE: Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the pinpoint test.

NOTE: Only disconnect or reconnect SRS components when instructed to do so within a pinpoint test step. Failure to follow this instruction may result in incorrect diagnosis of the SRS.

NOTE: Always make sure the correct OCSM component is being installed. Parts released for other vehicles may not be compatible even if they appear physically similar. Check the part number listed in the Ford parts catalog to make sure the correct component is being installed. If an incorrect OCSM component is installed, DTCs may set.

NOTE: The SRS must be fully operational and free of faults before releasing the vehicle to the customer.

Restraint Control Module-B (RCM-B) Connector - C310B

Circuit