Pinpoint Test Y: DTC B1921 - Air Bag Diagnostic Monitor Circuit Open
NOTE:
Most faults are due to connector and/or wiring concerns. Carry out a thorough Inspection and Verification before proceeding with the Pinpoint Test.
- Y1 CHECK FOR CONTINUOUS AND ON-DEMAND DTCs WARNING: Restraint system diagnostic tools are for service only. Tools must be removed prior to operating the vehicle over the road. Failure to remove restraint system diagnostic tools could result in injury and possible violation of vehicle safety standards.WARNING: Never probe the connectors on the air bag module. Doing so can result in air bag deployment, which can result in personal injury.WARNING: The safety belt pretensioner is a pyrotechnic device. Always wear safety glasses when repairing an air bag equipped vehicle and when handling a safety belt buckle pretensioner or safety belt retractor pretensioner. Never probe a pretensioner electrical connector. Doing so could result in pretensioner or air bag deployment and could result in personal injury.NOTE: After diagnosing or repairing an SRS, the restraint system diagnostic tools must be removed before operating the vehicle over the road.NOTE: The SRS must be fully operational and free of faults before releasing the vehicle to the customer.
- Enter the following diagnostic mode on the scan tool: On-Demand Self Test.
- Enter the following diagnostic mode on the scan tool: Retrieve/Record Continuous DTCs.
- Was DTC B1921 retrieved during the on-demand self test?
- Y2 INSPECT THE RCM MOUNTING, MOUNTING BRACKET AND MOUNTING SURFACE
- Key in OFF position.
- Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
- Inspect the RCM mounting and make sure that the retaining bolts are fully seated and tightened correctly.
- Remove the RCM. Refer to RESTRAINTS CONTROL MODULE (RCM) .
- Visually inspect the RCM, mounting bracket and mounting surface for damage, corrosion or dirt.
- Was a significant amount of corrosion or dirt found, the RCM mounting bracket attached to the mounting surface incorrectly or were the RCM bolts not fully seated and tightened correctly?
- Y3 INSTALL THE RCM AND CARRY OUT THE ON-DEMAND SELF TEST
- Clean the RCM mounting surfaces and bolts.
- Install the RCM. Refer to RESTRAINTS CONTROL MODULE (RCM) .
- Repower the system. Do not prove out the system at this time. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
- Enter the following diagnostic mode on the scan tool: On-Demand Self Test.
- Was DTC B1921 retrieved during the on-demand self test?
- Y4 CHECK THE RCM CASE GROUND FOR HIGH RESISTANCE
- Key in OFF position.
- Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
- Measure the resistance between the RCM case and a good sheet metal ground.
- Is the resistance less than 25 ohms?
- Yes : INSTALL and CONFIGURE a new RCM. Refer to RESTRAINTS CONTROL MODULE (RCM) . GO to Y6.
- No : REPAIR as necessary. GO to Y6.
- Y5 CHECK FOR AN INTERMITTENT FAULT
- Key in OFF position.
- Enter the following diagnostic mode on the scan tool: On-Demand Self Test.
- Was DTC B1921 retrieved during the on-demand self test?
- Yes
: This is a hard fault. The fault condition is now present. This fault cannot be cleared until it is corrected and the DTC is no longer retrieved during the on-demand self test.
GO to Y2.
- No : CHECK for causes of intermittent high resistance on the chassis ground. ATTEMPT to recreate the hard fault by flexing the wire harness and cycling the ignition key frequently. REPAIR any intermittent concerns found. GO to Y6.
- Y6 CHECK FOR ADDITIONAL DTCs
- Refer to the continuous DTCs recorded during Step Y1.
- Were any continuous DTCs retrieved during Step Y1?
- Yes : Do not clear any DTCs until all DTCs have been resolved. GO to the RESTRAINTS CONTROL MODULE (RCM) DIAGNOSTIC TROUBLE CODE (DTC) Table for pinpoint test direction.
- No : RECONNECT the system. If previously directed to deactivate the system, REACTIVATE the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEACTIVATION AND REACTIVATION . REPOWER the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING . PROVE OUT the system. CLEAR all DTCs.