Pinpoint Test U: The Air Bag Warning Indicator Is Never/Always On

WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: Use the correct probe adaptor(s) when making measurements. Failure to use the correct probe adaptor(s) may damage the connector.

U1 RETRIEVE THE RECORDED DIAGNOSTIC TROUBLE CODES (DTCs) FROM BOTH THE CONTINUOUS AND ON-DEMAND RCM SELF-TESTS
- Check for recorded RCM DTCs from the continuous and on-demand self-tests.
- Are any RCM DTCs recorded?
Yes : If DTC B1869 is present, GO to U3.

If DTC B1870 is present, GO to U4.

All other DTCs, REFER to SUPPLEMENTAL RESTRAINT SYSTEM to continue diagnosis of the DTCs.

No : GO to U2.
U2 CHECK THE RCM FOR CORRECT OPERATION
- Depower the supplemental restraint system (SRS). Refer to SUPPLEMENTAL RESTRAINT SYSTEM .
- Key in OFF position.
- Disconnect: RCM C310a.
- Connect the battery. Refer to BATTERY, MOUNTING AND CABLES .
- Connect a fused (10A) jumper wire between the RCM C310a-15, circuit 608 (BK/YE), harness side and ground.
  
  Fig 1: Connecting Fused (10A) Jumper Wire Between RCM C310A-15, Circuit 608 (BK/YE), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Key in ON position.
- Does the air bag indicator lamp illuminate after the instrument cluster proves out?
Yes : REMOVE the jumper wire. GO to U7.

No : REMOVE the jumper wire. GO to U3.
U3 CHECK CIRCUIT 608 (BK/YE) FOR AN OPEN
- Key in OFF position.
- Disconnect: RCM C310a.
- Disconnect: Instrument Cluster C220.
- Measure the resistance between the instrument cluster C2220-12, circuit 608 (BK/YE), harness side and the RCM C310a-15, circuit 608 (BK/YE), harness side.
  
  Fig 2: Measuring Resistance Between Instrument Cluster C2220-12 And RCM C310A-15, Circuit 608
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to U5.

No : REPAIR the circuit. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM . TEST the system for normal operation.
U4 CHECK CIRCUIT 608 (BK/YE) FOR A SHORT TO VOLTAGE
- Key in OFF position.
- Depower the SRS. Refer to SUPPLEMENTAL RESTRAINT SYSTEM .
- Disconnect: RCM C310a.
- Disconnect: Instrument Cluster C220.
- Connect the battery. Refer to BATTERY, MOUNTING AND CABLES .
- Key in ON position.
- Measure the voltage between instrument cluster C2220-12, circuit 608 (BK/YE), harness side and ground.
  
  Fig 3: Measuring Voltage Between Instrument Cluster C2220-12, Circuit 608 (BK/YE), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is any voltage present?
Yes : GO to U6.

No : REPAIR the circuit. CLEAR the DTCs REPEAT the self-test.
U5 CHECK CIRCUIT 608 (BK/YE) FOR A SHORT TO GROUND
- Measure the resistance between the instrument cluster C2220-12, circuit 608 (BK/YE), harness side and ground.
  
  Fig 4: Measuring Resistance Between Instrument Cluster C2220-12, Circuit 608 (BK/YE), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes : GO to U6.

No : REPAIR the circuit. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM . TEST the system for normal operation.
U6 CHECK FOR CORRECT INSTRUMENT CLUSTER OPERATION
- Disconnect the instrument cluster connector.
- Check for:
  - corrosion
  - pushed-out pins
- Connect the instrument cluster connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes : INSTALL a new instrument cluster. REFER to INSTRUMENT CLUSTER . REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM . TEST the system for normal operation.

No : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM .
U7 CHECK FOR CORRECT RCM OPERATION
- Disconnect all the RCM connectors.
- Check for:
  - corrosion
  - pushed-out pins
- Connect all the RCM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes : INSTALL a new RCM and REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM . TEST the system for normal operation.

No : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM .