Pinpoint Test M: LFC 51/DTC B2434 - Driver Safety Belt Buckle Switch Circuit Short To Ground

WARNING: This page is about a different car, the 2005 Ford Pickup. 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 a thorough Inspection and Verification before proceeding with the pinpoint test.

M1 CHECK FOR A HARD OR INTERMITTENT DTC
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 diagnostic tool: On-Demand Self Test.
- Enter the following diagnostic mode on the diagnostic tool: Retrieve/Record Continuous DTCs.
- Was DTC B2434 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 DTC is no longer retrieved during the on-demand self test. GO to M2.
- No : This is an intermittent fault. The fault condition is not present at this time. GO to M5.
M2 CHECK CIRCUIT 85 (BN/LB) FOR A SHORT TO GROUND
- Key in OFF position.
- Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM SRS DEPOWERING AND REPOWERING .
- Disconnect: Driver Safety Belt Buckle Switch C3065.
- Disconnect: RCM C310a and C310b.
- Measure the resistance between RCM C310b pin 25, circuit 85 (BN/LB), harness side and ground.
  
  Fig 1: Measuring Resistance Between RCM C310b Pin 25, Circuit 85 (BN/LB), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 1,000,000 ohms?
- Yes : GO to M3.
- No : REPAIR circuit 85 (BN/LB). GO to M6.
M3 CHECK THE DRIVER SAFETY BELT BUCKLE SWITCH
- Install a known good safety belt buckle switch. REFER to SAFETY BELT SYSTEM .
- Connect: RCM C310a and C310b.
- 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 diagnostic tool: On-Demand Self Test.
- Was DTC B2434 retrieved during the on-demand self test?
- Yes : GO to M4.
- No : Fault corrected. GO to M6.
M4 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.
- Key in OFF position.
- Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM SRS DEPOWERING AND REPOWERING .
- Reinstall the original safety belt buckle switch.
- 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 diagnostic tool: On-Demand Self-Test.
- Was DTC B2434 retrieved during the on-demand self test?
- Yes : INSTALL a new RCM. REFER to RESTRAINTS CONTROL MODULE RCM . GO to M6.
- 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. ACTIVATE other systems in the same wire harness. REPAIR any intermittent concerns found. GO to M6.
M5 CHECK FOR AN INTERMITTENT FAULT
- Key in OFF position.
- Enter the following diagnostic mode on the diagnostic tool: On-Demand Self Test.
- Was DTC B2434 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 M2.
- 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. ACTIVATE other systems in the same wire harness. REPAIR any intermittent concerns found. GO to M6.
M6 CHECK FOR ADDITIONAL DTCs
- Refer to the continuous DTCs recorded during Step M1.
- Were any continuous DTCs retrieved during Step M1 ?
- 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.