Pinpoint Test S: LFC 19/DTC B1936 - Driver Air Bag Circuit Shorted To Ground

WARNING: This page is about a different car, the 2005 Ford RV Cutaway, 2005 Ford Econoline, 2005 Ford E450 Super Duty, and 2005 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Most faults are due to connector and/or wiring concerns. Carry out thorough Inspection and Verification before proceeding with the Pinpoint Test.

S1 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.

CAUTION: To avoid potential damage to the restraints control module (RCM), make sure the RCM and bracket assembly is secured to the floor pan and the SRS is depowered before either disconnecting or reconnecting the RCM electrical connectors.

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: Retrieve/Record Continuous DTCs.
- Enter the following diagnostic mode on the scan tool: On-Demand Self Test.
- Was DTC B1936 retrieved during the on-demand self test?
- Yes : This is a hard fault. The fault condition is still 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 S2.
- No : This is an intermittent fault. The fault condition is not present at this time. GO to S6.
S2 CHECK THE DRIVER AIR BAG MODULE
- Key in OFF position.
- Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
- Remove the driver air bag module. Refer to DRIVER AIR BAG MODULE .
- Attach restraint system diagnostic tool 418-F395 to the clockspring side of the driver air bag module electrical connector.
- 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 B1936 retrieved during the on-demand self test?
- Yes : GO to S3.
- No : INSTALL a new driver air bag module. REFER to DRIVER AIR BAG MODULE . GO to S7.
S3 CHECK THE DRIVER AIR BAG MODULE CIRCUIT
- Key in OFF position.
- Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
- Disconnect: RCM C310a.
- Disconnect: Driver Air Bag Module Restraint System Diagnostic Tool.
- Measure the resistance between RCM C310a pin 1, circuit 614 (GY/OG), harness side and ground; and between RCM C310a pin 2, circuit 615 (GY/WH), harness side and ground.
  
  Fig 1: Measuring Resistance Between RCM Pin 1 And Ground
  Courtesy of FORD MOTOR CO.
- Are the resistances greater than 10,000 ohms?
- Yes : GO to S5.
- No : GO to S4.
S4 CHECK THE DRIVER AIR BAG MODULE WIRING AND THE CLOCKSPRING
- Disconnect: Clockspring C218a.
- Measure the resistance between RCM C310a pin 1, circuit 614 (GY/OG), harness side and ground; and between RCM C310a pin 2, circuit 615 (GY/WH), harness side and ground.
  
  Fig 2: Measuring Resistance Between RCM Pin 1 And Ground
  Courtesy of FORD MOTOR CO.
- Are the resistances greater than 10,000 ohms?
- Yes : INSTALL a new clockspring. REFER to CLOCKSPRING . GO to S7.
- No : Due to the shorting bar feature in the electrical connector, the fault can exist in either circuit. Do not remove or defeat the shorting bar.
REPAIR circuit 614 (GY/OG) or circuit 615 (GY/WH). GO to S7.
S5 CONFIRM THE RCM FAULT
NOTE: Make sure all restraint system diagnostic tools, sensor electrical connectors and the RCM electrical connector are connected before carrying out the on-demand self test. If not, erroneous DTCs will be recorded.
- Connect: RCM C310a.
- Connect: Driver Air Bag Module Restraints Diagnostic System Tool.
- 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 B1936 retrieved during the on-demand self test?
- Yes : INSTALL a new RCM. REFER to RESTRAINTS CONTROL MODULE (RCM) . GO to S7.
- No : CHECK for causes of intermittent short to ground on circuit 614 (GY/OG), circuit 615 (GY/WH), and the clockspring assembly. ATTEMPT to recreate the hard fault by flexing the wire harness and cycling the ignition key frequently. REPAIR any intermittent concerns found. GO to S7.
S6 CHECK FOR AN INTERMITTENT FAULT
- Key in OFF position.
- Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
- Remove the driver air bag module. Refer to DRIVER AIR BAG MODULE .
- Attach restraint system diagnostic tool 418-F395 to the clockspring side of the driver air bag module electrical connector.
- 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 B1936 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.
  CHECK for causes of the intermittent fault at or near the affected air bag module connector. REPAIR any intermittent concerns found.
  
  If an intermittent concern was found and repaired, GO to S7.
  
  If an intermittent concern was not found and repaired, GO to S3.
- No : CHECK for causes of intermittent short to ground on circuit 614 (GY/OG), circuit 615 (GY/WH), and the clockspring assembly. ATTEMPT to recreate the hard fault by flexing the wire harness and cycling the ignition key frequently. REPAIR any intermittent concerns found. GO to S7.
S7 CHECK FOR ADDITIONAL DTCs
- Refer to the continuous DTCs recorded during Step S1.
- Were any continuous DTCs retrieved during Step S1 ?
- Yes : Do not clear any DTCs until all DTCs have been resolved. GO to the RESTRAINTS CONTROL MODULE (RCM) DIAGNOSTIC TROUBLE CODE (DTC) PRIORITY 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.