Pinpoint Test C: The Restraints Control Module (RCM) Does Not Respond To The Diagnostic Tool

WARNING: This page is about a different car, the 2005 Mercury Mountaineer and 2005 Ford Explorer. 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.

NOTE: The ISO 9141 communications network diagnostics requires depower of the supplemental restraint system (SRS) when disconnecting the restraint control module (RCM) C310a. When Key ON occurs to carry out the data link diagnostic test, diagnostic trouble codes (DTCs) may be stored in the RCM. These DTCs should be cleared when network diagnostics are completed.

NOTE: The SRS must be fully operational and free of faults before releasing the vehicle to the customer.

C1 CHECK THE RCM CONNECTION
- Key in OFF position.
- Depower the SRS. Refer to SUPPLEMENTAL RESTRAINT SYSTEM .
- Connect: RCM C310a.
- Is RCM C310a fully connected and the connector locking tab engaged?
- Yes : GO to C2.
- No : CONNECT C310a and ENGAGE the locking tab.
  REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM . CARRY OUT the diagnostic tool data link test.
C2 CHECK THE RCM C310A FOR DAMAGE
- Disconnect: RCM C310a.
- Inspect the RCM C310a for damage.
- Is the RCM C310a OK?
- Yes : GO to C3.
- No : REPAIR the RCM C310a. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM . CARRY OUT the diagnostic tool data link test.
C3 CHECK THE RCM VOLTAGE CIRCUIT 1003 (GY/YE) FOR AN OPEN
- Repower the SRS. Refer to SUPPLEMENTAL RESTRAINT SYSTEM .
- Key in ON position.
- Measure the voltage between RCM C310a-12, circuit 1003 (GY/YE), harness side and ground.
  
  Fig 1: Measuring Voltage Between RCM Connector And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage between 9 and 16 volts?
- Yes : GO to C4.
- No : VERIFY the central junction box (CJB) fuse 19 (10A) is OK. If OK, REPAIR the circuit.
  REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM .
  
  CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.
C4 CHECK THE RCM GROUND CIRCUIT 649 (BK/OG) FOR AN OPEN
- Key in OFF position.
- Depower the SRS. Refer to SUPPLEMENTAL RESTRAINT SYSTEM .
- Measure the resistance between RCM C310a-16, circuit 649 (BK/OG), harness side and ground.
  
  Fig 2: Measuring Resistance Between RCM connector And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : GO to C5.
- No : REPAIR the circuit.
  REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM .
  
  CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.
C5 CHECK THE ISO 9141 CIRCUIT BETWEEN THE RCM AND THE DLC FOR AN OPEN
- Measure the resistance between the RCM C310a-11, circuit 70 (LB/WH), harness side and the DLC C251-7, circuit 70 (LB/WH), harness side.
  
  Fig 3: Measuring Resistance Between RCM C310a-11 And DLC C251-7
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : GO to C6.
- No : REPAIR the circuit.
  REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM .
  
  CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.
C6 CHECK FOR CORRECT RCM OPERATION
- Disconnect all the RCM connectors.
- Check for:
  - corrosion
  - push-out pins
- Connect all the RCM connectors and make sure they seat correctly.
- Repower the SRS. Refer to SUPPLEMENTAL RESTRAINT SYSTEM .
- Operate the system and verify the concern is still present.
- Is the concern still present?
- Yes : INSTALL a new RCM. REFER to SUPPLEMENTAL RESTRAINT SYSTEM . CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.
- 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 .
  
  CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.