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Home >> Ford >> 1997 >> Taurus G, AX4N >> Repair and Diagnosis (Single Page) >> Restraints >> Air Bag, SRS >> Supplemental Inflatable Restraint System >> Diagnostic Tests >> DTC B1939 - Passenger-Side Air Bag Pressure Switch Low Resistance Or Shorted To Ground >> Test Procedure

Test Procedure

  1. Verify Condition

    Connect NGS tester to DLC. Perform RETRIEVING FAULT CODES  . If DTC B1939 is retrieved, go to next step. If DTC B1939 is not retrieved, service remaining DTCs.

  2. Perform On-Demand Self Test

    Connect NGS to DLC. Perform ON-DEMAND SELF-TEST  . If DTC B1937 is retrieved, go to next step. If DTC B1939 is not retrieved, fault is intermittent and not present at this time. Go to step 5).

  3. Measure Resistance

    Deactivate SRS. See DISABLING & ACTIVATING AIR BAG SYSTEM  . Disconnect air bag diagnostic monitor. Set ohmmeter to 200 ohm scale or AUTO. Zero ohmmeter by touching leads together and record resistance reading. Measure resistance between air bag diagnostic monitor harness connector terminals C277-7, circuit 626 (Purple wire) and C276-18, circuit 57 (Black wire). If resistance is 235-265 ohms, replace air bag diagnostic monitor. See DIAGNOSTIC MONITOR  under REMOVAL & INSTALLATION. Reconnect and verify system. Go to step 8). If resistance is not as specified, go to next step.

  4. Check Passenger-Side Air Bag Module

    Disconnect passenger-side air bag module switch connector. Using ohmmeter with less than 10MA short circuit current, measure resistance between pressure switch terminals on passenger-side air bag pressure switch connector. If resistance is 235-265 ohms, service short to ground in circuit 626 (Purple wire). Reconnect system and go to step 8). If resistance is not as specified, replace passenger-side air bag module. See PASSENGER-SIDE AIR BAG MODULE  under REMOVAL & INSTALLATION. Go to step 8).

  5. Check For Serviced DTC

    Deactivate SRS. See DISABLING & ACTIVATING AIR BAG SYSTEM  . If DTC B1939 has just been serviced, go to step 8). If DTC B1939 has not just been serviced, go to next step.

  6. Check Connector

    Check passenger-side air bag pressure switch wiring where air bag connects to harness, for signs of chafed wires or wire-to-wire shorts. If no problems are found, go to next step. If problems are found, service as necessary and go to step 8).

  7. Check Circuits 626 And 57

    Inspect wiring and connections in circuit 626 (Purple wire) and 57 (Black wire) feeding passenger-side air bag pressure switch. Look for pinches or areas of potential intermittent shorts between these circuits. If problems are found, service as necessary and replace passenger-side air bag module. See PASSENGER-SIDE AIR BAG MODULE  under REMOVAL & INSTALLATION. Go to next step. If no problems are found, look for causes of intermittent shorts in appropriate circuits. Attempt to recreate hard faults by driving vehicle, flexing wire harnesses, etc. Repair intermittent problems. Go to next step.

  8. Check For Other DTCs

    Connect NGS to DLC. If other DTCs are retrieved go to proper DTC test. If no other DTCs are retrieved, reactivate system and clear all DTCs. See DISABLING & ACTIVATING AIR BAG SYSTEM  .
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