Pinpoint Test BB: DTC B2856 - Front Crash Sensor Id Fault

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

BB1 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 B2856 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 BB2.
- No : This is an intermittent fault. The fault condition is not present at this time. GO to BB5.
BB2 CHECK THE FRONT IMPACT SEVERITY SENSOR PART NUMBER
- Key in OFF position.
- Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
- Check the part number on the front impact severity sensor against the part number listed in the master parts catalog.
- Did the part number on the front impact severity sensor match the part number listed in the master parts catalog?
- Yes : GO to BB3.
- No : INSTALL a new front impact severity sensor. Refer to FRONT IMPACT SEVERITY SENSOR . GO to BB6.
BB3 CHECK THE FRONT IMPACT SEVERITY SENSOR
- Install a known good front impact severity sensor. Refer to FRONT IMPACT SEVERITY SENSOR .
- 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 B2856 retrieved during the on-demand self test?
- Yes : GO to BB4.
- No : Fault corrected. GO to BB6.
BB4 CONFIRM THE RCM FAULT
NOTE: Make sure all restraint system diagnostic tools, sensor electrical connectors, and the RCM electrical connectors 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 front impact severity sensor. Refer to FRONT IMPACT SEVERITY SENSOR .
- 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 B2856 retrieved during the on-demand self test?
- Yes : INSTALL and CONFIGURE a new RCM. Refer to RESTRAINTS CONTROL MODULE (RCM) . GO to BB6.
- 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 BB6.
BB5 CHECK FOR AN INTERMITTENT FAULT
- Key in OFF position.
- Enter the following diagnostic mode on the scan tool: On-Demand Self Test.
- Was DTC B2856 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 BB2.
- 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 BB6.
BB6 CHECK FOR ADDITIONAL DTCs
- refer to the continuous DTCs recorded during Step BB1.
- Were any continuous DTCs retrieved during Step BB1?
- Yes : Do not clear any DTCs until all DTCs have been resolved. GO to the RESTRAINTS CONTROL MODULE (RCM) DIAGNOSTIC TROUBLE CODE (DTC) INDEX 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.