Pinpoint Test D: LFC 33/DTC B1877/B1885 - Driver PRETENSIONER Circuit Resistance High Or Low

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.

D1 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 B1877 or B1885 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 D2.
- No : This is an intermittent fault. The fault condition is not present at this time. GO to D5.
D2 CHECK DRIVER SAFETY BELT PRETENSIONER RESISTANCE
- Key in OFF position.
- Enter the following diagnostic mode on the scan tool: PID/Data Monitor and Record.
- Select PID D_PRTNR.
- Is the resistance greater than 3.2 or less than 1.7 ohms?
- Yes : If the PID D_PRTNR is greater than 3.2 ohms, GO to D3.
  If the PID D_PRTNR is less than 1.7 ohms, GO to D4.
- No : INSTALL a new RCM. REFER to RESTRAINTS CONTROL MODULE (RCM) . GO to D6.
D3 CHECK THE DRIVER SAFETY BELT PRETENSIONER CIRCUITS FOR HIGH RESISTANCE
- Key in OFF position.
- Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
- Disconnect: Driver Safety Belt Pretensioner C323.
- Disconnect: RCM C310b.
- Measure the resistance between RCM C310b pin 17, circuit 1079 (LG/RD), harness side and the driver safety belt pretensioner C323 pin 1, circuit 1079 (LG/RD), harness side; and between RCM C310b pin 18, circuit 1080 (LG/BK), harness side and the driver safety belt pretensioner C323 pin 2, circuit 1080 (LG/BK), harness side.
  
  Fig 1: Measuring Resistance Between RCM Pin 17 Harness Side And Driver Safety Belt Pretensioner Pin 1 Harness Side
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 0.5 ohm?
- Yes : INSTALL a new driver safety belt pretensioner. REFER to SAFETY BELT SYSTEM . GO to D6.
- No : REPAIR circuit 1079 (LG/RD) or circuit 1080 (LG/BK). GO to D6.
D4 CHECK THE DRIVER SAFETY BELT PRETENSIONER CIRCUITS FOR LOW RESISTANCE
- Key in OFF position.
- Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
- Disconnect: Driver Safety Belt Pretensioner C323.
- Disconnect: RCM C310b.
- Measure the resistance between C323 pin 1, circuit 1079 (LG/RD), and pin 2, circuit 1080 (LG/BK), harness side.
  
  Fig 2: Measuring Resistance Between Pins 1 And 2
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
- Yes : INSTALL a new driver safety belt pretensioner. REFER to SAFETY BELT SYSTEM . GO to D6.
- No : REPAIR circuit 1079 (LG/RD) and circuit 1080 (LG/BK). GO to D6.
D5 CHECK FOR AN INTERMITTENT FAULT
- Key in OFF position.
- Enter the following diagnostic mode on the scan tool: On-Demand Self Test.
- Was DTC B1885 or B1877 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 faults on circuits 1080 (LG/BK) and 1079 (LG/RD). REPAIR any intermittent concerns found.
  
  If an intermittent concern was found and repaired, GO to D6.
  
  If an intermittent concern was not found and repaired, GO to D2.
- No : CHECK for causes of the intermittent fault. ATTEMPT to recreate the hard fault by flexing the wire harness and cycling the ignition key frequently. REPAIR any intermittent concerns found. GO to D6.
D6 CHECK FOR ADDITIONAL DTCs
- Refer to the continuous DTCs recorded during Step D1.
- Were any continuous DTCs retrieved during Step D1 ?
- 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.