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Pinpoint Test Aa: DTC B272B - Passenger Back Over-Temp Detected

WARNING: This page is about a different car, the 2009 Mercury Milan, 2009 Lincoln MKZ, and 2009 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: The air bag warning indicator illuminates when the correct restraints control module (RCM) fuse is removed and the ignition switch is ON.
NOTE: The supplemental restraint system (SRS) must be fully operational and free of faults before releasing the vehicle to the customer.
  1. AA1 CHECK THE DCSM FOR DTCs 
    • Connect the diagnostic tool.
    • Enter the following diagnostic mode on the diagnostic tool: Self-Test/DCSM Retrieve DTCs
    • Was DTC B2730 retrieved during the self-test? 
    1. YES  : Go to  AA2.
    2. NO  : Go to  AA4.
  2. AA2 CHECK THE TED THERMISTOR CIRCUITS FOR A SHORT TO GROUND 
    • Key in OFF position.
    • Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of SUPPLEMENTAL RESTRAINT SYSTEM article.
    • Disconnect the passenger seat side air bag C313.
    • Disconnect: DCSM C3305b
    • Disconnect: Backrest TED C3311
      • WARNING: Make sure no one is in the vehicle and there is nothing blocking or placed in front of any air bag module when the battery is connected. Failure to follow these instructions may result in serious personal injury in the event of an accidental deployment.
    • Connect the battery ground cable. Refer to BATTERY, MOUNTING AND CABLES article.
      • Fig 1: Checking TED Thermistor Circuits For A Short To Ground
      GF0021407Courtesy of FORD MOTOR CO.
    • Measure the resistance between DCSM C3305b-4, circuit VHS36 (YE/BU), harness side and ground and between DCSM C3305b-5, circuit RHS20 (GN/BU), harness side and ground.
    • Are the resistances greater than 10,000 ohms? 
    1. YES  : Go to  AA3.
    2. NO  : REPAIR the affected circuit. REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article.

  3. AA3 CHECK THE TED THERMISTOR 
      Fig 2: Checking Blower Speed Control
      GF0021397Courtesy of FORD MOTOR CO.
    • Measure the resistance between backrest TED C3311 pin 5 and pin 8, component side. Note the ambient temperature and refer to the following table.
      Temperature Resistance
      0-10°C (32-50°F) 2,782-1,663 ohms
      10-20°C (50-68°F) 1,837-1,140 ohms
      20-30°C (68-86°F) 1,260-806 ohms
      30-40°C (86-104°F) 893-570 ohms
      40-50°C (104-122°F) 630-428 ohms
    • Is the resistance within the limits indicated? 
    1. YES  : REPAIR the affected open circuit. REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article.

    2. NO  : INSTALL a new backrest TED. REFER to Seat Backrest Thermo-Electric Device . REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article.

  4. AA4 CONFIRM THE FAULT 
    • Verify with the customer that the concern is the seat shuts OFF in heat mode.
      • NOTE: A crushed seat backrest foam pad or a crushed climate controlled seat manifold may be the cause of the fault. It may be necessary to sit on the seat or place something of reasonable size and weight on the seat to recreate the fault.
    • Attempt to recreate the fault. Start the vehicle and set the front passenger seat to high heat for at least 15 minutes.
    • Is the customer concern with the seat shutting OFF in heat mode or was the fault recreated? 
    1. YES  : Go to  AA5.
    2. NO  : Fault not present. Fault may have been set due to a past failure or incorrect use of the climate controlled seat system by repeated switching between HEAT and COOL modes. REPEAT the self-test. CLEAR the DTCs.
  5. AA5 CHECK OPERATION OF THE SEAT 
    • Key in ON position.
    • With the engine running, set both front seats to high cool (3 LEDs illuminated on HVAC module).
    • Compare the airflow from the front passenger seat backrest and compare it to the airflow from the driver seat backrest.
    • Is the airflow exhausting from the front passenger seat backrest comparable to the airflow exhausting from the driver seat backrest? 
    1. YES  : Go to  AA14.
    2. NO  : Go to  AA6.
  6. AA6 CHECK THE BACKREST BLOWER FOR AN OBSTRUCTION OR RESTRICTED FILTER 
    • Key in OFF position.
    • Inspect the blower of the backrest TED assembly for an obstruction or for a restricted filter.
    • Is the blower obstructed or the filter restricted? 
    1. YES  : REMOVE the obstruction or INSTALL a new filter. REPEAT the self-test. CLEAR the DTCs.
    2. NO  : Go to  AA7.
  7. AA7 CHECK THE BACKREST FAN OPERATION 
    • Key in ON position.
    • With the engine running, set both front seats to high cool (3 LEDs illuminated on HVAC module).
    • Inspect the backrest blower for operation.
    • Does the backrest blower operate? 
    1. YES  : Go to  AA14.
    2. NO  : Go to  AA8.
  8. AA8 CHECK THE BLOWER SPEED CONTROL CIRCUIT FOR AN OPEN 
    • Key in OFF position.
    • Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of SUPPLEMENTAL RESTRAINT SYSTEM article.
    • Disconnect the passenger seat side air bag C313.
    • Disconnect: DCSM C3305c
    • Disconnect: Backrest TED C3311
      • WARNING: Make sure no one is in the vehicle and there is nothing blocking or placed in front of any air bag module when the battery is connected. Failure to follow these instructions may result in serious personal injury in the event of an accidental deployment.
    • Connect the battery ground cable. Refer to BATTERY, MOUNTING AND CABLES article.
      • Fig 3: Checking Blower Speed Control Circuit For Open
      GF0028302Courtesy of FORD MOTOR CO.
    • Measure the resistance between DCSM C3305c-4, circuit VHS21 (BU/WH), harness side and backrest TED C3310-7, circuit VHS21 (BU/WH), harness side.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  AA9.
    2. NO  : REPAIR the circuit. REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article.

  9. AA9 CHECK BLOWER CIRCUIT RHS08 (VT/WH) FOR A SHORT TO VOLTAGE 
    • Key in ON position.
      • Fig 4: Measuring Voltage
      GF0021405Courtesy of FORD MOTOR CO.
    • Measure the voltage between DCSM C3305c-7, circuit RHS08 (VT/WH), harness side and ground.
    • Is voltage greater than 1 volt? 
    1. YES  : REPAIR the circuit. REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article.

    2. NO  : Go to  AA10.
  10. AA10 CHECK BLOWER CIRCUIT CHS08 (BN/YE) FOR A SHORT TO GROUND 
    • Key in OFF position.
      • Fig 5: Measuring Resistance
      GF0021394Courtesy of FORD MOTOR CO.
    • Measure the resistance between DCSM C3305c-8, circuit CHS08 (BN/YE), harness side and ground.
    • Is the resistance greater than 10,000 ohms? 
    1. YES  : Go to  AA11.
    2. NO  : REPAIR the circuit. REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article.

  11. AA11 CHECK BLOWER CIRCUITS CHS08 (BN/YE) AND RHS08 (VT/WH) FOR AN OPEN 
      Fig 6: Checking Circuit For Open
      GF0021406Courtesy of FORD MOTOR CO.
    • Measure the resistance between DCSM C3305c-8, circuit CHS08 (BN/YE), harness side and backrest TED C3311-2, circuit CHS08 (GY/RD), harness side; and between DCSM C3305c-7, circuit RHS08 (VT/WH), harness side and backrest TED C3311-4, circuit RHS08 (VT/WH), harness side.
    • Are the resistances less than 5 ohms? 
    1. YES  : Go to  AA12.
    2. NO  : REPAIR the affected circuit. REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article.

  12. AA12 CHECK THE BLOWER RESISTANCE 
      Fig 7: Checking Blower Resistance
      GF0021401Courtesy of FORD MOTOR CO.
      NOTE: The ohmmeter must be connected with the positive lead to pin 2 and the negative lead to pin 4 when measuring. Ohmmeter leads incorrectly connected will result in false readings and lead to incorrect identification of components that are not faulty.
    • Measure the resistance between backrest TED C3311 pin 2 and pin 4, component side.
    • Is the resistance between 6K ohms and 9K ohms? 
    1. YES  : Go to  AA13.
    2. NO  : INSTALL a new backrest TED. REFER to Seat Backrest Thermo-Electric Device . REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article.

  13. AA13 CHECK THE BLOWER SPEED CONTROL RESISTANCE 
      Fig 8: Checking Blower Speed Control
      GF0021397Courtesy of FORD MOTOR CO.
      NOTE: The ohmmeter must be connected with the positive lead to pin 7 and the negative lead to pin 4 when measuring. Ohmmeter leads incorrectly connected will result in false readings and lead to incorrect identification of components that are not faulty.
    • Measure the resistance between backrest TED C3311 pin 7 and pin 4, component side.
    • Is the resistance between 290K ohms and 420K ohms? 
    1. YES  : Go to  AA14.
    2. NO  : INSTALL a new backrest TED. REFER to Seat Backrest Thermo-Electric Device . REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article.

  14. AA14 CHECK THE TED INSTALLATION AND FOR CRUSHED SEAT BACKREST 
    • Key in OFF position.
    • Remove the seat. Refer to Seat - Front .
    • Remove the seat backrest trim cover. Refer to Seat Backrest Cover - Front, Without Fold Flat .
    • Inspect the seat backrest for the following:
      • Is the TED correctly installed?
      • Is the seat backrest foam pad crushed or restricted?
      • Is the climate controlled seat manifold crushed or restricted?
    • Is the TED correctly installed and are there no signs of damage to the foam pad and manifold? 
    1. YES  : INSTALL a new DCSM and CARRY OUT programmable module installation (PMI). REFER to Dual Climate Controlled Seat Module (DCSM) . REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article.

    2. NO  : CORRECTLY install the backrest TED or INSTALL a new seat backrest foam pad and/or climate controlled seat manifold. REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article.

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