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Home >> Mercury >> 2009 >> Mariner Base, 2.5 7, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 142 (Supplemental Restraint System) >> Diagnostic Tests >> Air Bag And Safety Belt PRETENSIONER Supplemental Restraint System (SRS) >> Pinpoint Tests >> Pinpoint Test H: B1921 - Air Bag Diagnostic Monitor Ground Circuit Open >> Pinpoint Test H: DTC B1921 - Air Bag Diagnostic Monitor Ground Circuit Open

Pinpoint Test H: DTC B1921 - Air Bag Diagnostic Monitor Ground Circuit Open

WARNING: This page is about a different car, the 2009 Mercury Grand Marquis and 2009 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.
WARNING: Remove restraint system diagnostic tools from the vehicle prior to road testing. If tools are not removed, the supplemental restraint system (SRS) device may not deploy in a crash. Failure to follow this instruction may result in serious personal injury or death in a crash and possibly violate vehicle safety standards.
WARNING: Never probe the electrical connectors on air bag, safety canopy or side air curtain modules. Failure to follow this instruction may result in the accidental deployment of these modules, which increases the risk of serious personal injury or death.
NOTE: Use the correct probe adapter(s) when taking measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: The Supplemental Restraint System (SRS) must be fully operational and free of faults before releasing the vehicle to the customer.
NOTE: SRS components should only be disconnected or reconnected when instructed to do so within a pinpoint test step. Failure to follow this instruction may result in incorrect diagnosis of the SRS. 
NOTE: Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the Pinpoint Test.
  1. H1 CHECK FOR ON-DEMAND AND CONTINUOUS DTCs 
    • Enter the following diagnostic mode on the diagnostic tool: Self Test - RCM
    • Was on-demand DTC B1921 retrieved? 
    1. 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  H2.
    2. NO  : This is an intermittent fault when present as a continuous memory DTC only (DTC not retrieved on demand). The fault condition is not present at this time. Go to  H6.
  2. H2 INSPECT THE RCM MOUNTING, MOUNTING BRACKET AND MOUNTING SURFACE 
    • Key in OFF position.
    • Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering .
    • Inspect the RCM retainers and RCM bracket mounting bolts and make sure they 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, or was the RCM mounting bracket attached to the mounting surface incorrectly or were the RCM retainers not fully seated and tightened correctly? 
    1. YES  : CLEAN and TIGHTEN the retainers. REPAIR the mounting surface as necessary. REINSTALL the RCM and mounting bracket to the mounting surface. Go to  H7.
    2. NO  : Go to  H3.
  3. H3 INSTALL THE RCM AND CARRY OUT THE ON-DEMAND SELF TEST 
    1. YES  : Go to  H4.
    2. NO  : CHECK for causes of intermittent high resistance on circuit 676 (PK/OG) or the chassis ground. 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 wiring, terminal or connector concerns found. Go to  H7.
  4. H4 CHECK GROUND CIRCUIT 676 (PK/OG) FOR HIGH RESISTANCE 
    1. YES  : Go to  H5.
    2. NO  : REPAIR circuit 676 (PK/OG). Go to  H7.
  5. H5 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.
    1. YES  : INSTALL a new RCM. REFER to Restraints Control Module (RCM) . Go to  H7.
    2. 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. Do not install any new SRS components at this time. SRS components should only be installed when directed to do so in the pinpoint test.  REPAIR any intermittent wiring, terminal or connector concerns found. Go to  H7.
  6. H6 CHECK FOR AN INTERMITTENT FAULT 
    • Enter the following diagnostic mode on the diagnostic tool: Self Test - RCM
    • Was on-demand DTC B1921 retrieved? 
    1. 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  H2.
    2. NO  :
    3. CHECK for causes of intermittent high resistance on circuit 676 (PK/OG) or the chassis ground. 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. Do not install any new SRS components at this time. SRS components should only be installed when directed to do so in the pinpoint test.  REPAIR any intermittent wiring, terminal or connector concerns found. Go to  H7.
  7. H7 CHECK FOR ADDITIONAL SRS DTCs 
    • Key in OFF position.
      WARNING: Turn the ignition OFF and wait one minute to deplete the backup power supply. Failure to follow this instruction may result in serious personal injury or death in the event of an accidental deployment.
    • Reconnect all SRS components (if previously disconnected).
    • Key in ON position.
    • Enter the following diagnostic mode on the diagnostic tool: Self Test - RCM
    • Are any on-demand DTCs retrieved? 
    1. YES  : Do not clear any DTCs until all DTCs have been resolved. Go to the SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DIAGNOSTIC TROUBLE CODE INDEX  for pinpoint test direction.
    2. NO  : CLEAR all RCM continuous memory DTCs. PROVE OUT the SRS. REPAIR is complete. RETURN the vehicle to the customer.
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