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Pinpoint Test As: DTC B272B

WARNING: This page is about a different car, the 2010 Lincoln MKX and 2010 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: When taking measurements at Dual Climate Controlled Seat Module (DCSM) harness connectors, do not insert the electrical probes into the female connector pins. Inserting the probes into connector pins can cause intermittent or open electrical connections after reassembly resulting in Diagnostic Trouble Codes (DTCs) and system failure. Touching the tip of these connector pins is recommended instead.
NOTE: The air bag warning indicator illuminates when the correct Restraints Control Module (RCM) fuse is removed and the ignition is ON.
NOTE: The Supplemental Restraint System (SRS) must be fully operational and free of faults before releasing the vehicle to the customer.
  1. AS1 CHECK THE DCSM FOR DTCs 
    • Enter the following diagnostic mode on the scan tool: Self Test - DCSM  .
    • Was DTC B272B retrieved during the self-test? 
    • Yes:  GO to AS2  .
    • No:  GO to  AS4.
  2. AS2 CHECK THE TED THERMISTOR CIRCUITS FOR A SHORT TO GROUND 
    • Ignition OFF.
    • Depower the SRS  . Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
    • Disconnect: Passenger Seat Side Air Bag C327.
    • Disconnect: DCSM  C3036b.
    • Disconnect: Backrest TED  C3326.
    • Measure the resistance between:
      • DCSM  C3036b-4, circuit VHS36 (YE/BU), harness side and ground.
      • DCSM  C3036b-5, circuit RHS20 (GN/BU), harness side and ground.
        Fig 1: Measuring Resistance Between DCSM C3036b-4, Circuit VHS36 (YE/BU), Harness Side And Ground
        G06134455Courtesy of FORD MOTOR CO.
    • Are the resistances greater than 10,000 ohms? 
  3. AS3 CHECK THE TED THERMISTOR 
    • Measure the resistance between backrest TED  C3326 pin 5 and pin 8, component side. Note the ambient temperature and refer to the following table.
      TEMPERATURE AND RESISTANCE REFERENCE CHART

      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
      Fig 2: Measuring Resistance Between Cushion TED C3328 Pin 5 And Pin 8, Component Side
      G06076995Courtesy of FORD MOTOR CO.
    • Is the resistance within the limits indicated? 
  4. AS4 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? 
    • Yes:  GO to AS5  .
    • 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. AS5 CHECK OPERATION OF THE SEAT 
    • Ignition ON.
    • 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? 
    • Yes:  GO to  AS14.
    • No:  GO to AS6  .
  6. AS6 CHECK THE BACKREST BLOWER FOR AN OBSTRUCTION OR RESTRICTED FILTER 
    • Ignition OFF.
    • Inspect the blower of the backrest TED  assembly for an obstruction or for a restricted filter.
    • Is the blower obstructed or the filter restricted? 
    • Yes:  REMOVE the obstruction or INSTALL a new filter. REPEAT the self-test. CLEAR the DTCs.
    • No:  GO to AS7  .
  7. AS7 CHECK THE BACKREST FAN OPERATION 
    • Ignition ON.
    • 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? 
    • Yes:  GO to  AS14.
    • No:  GO to AS8  .
  8. AS8 CHECK THE BLOWER SPEED CONTROL CIRCUIT FOR AN OPEN 
    • Ignition OFF.
    • Depower the SRS  . Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
    • Disconnect: Passenger Seat Side Air Bag C327.
    • Disconnect: DCSM  C3036c.
    • Disconnect: Backrest TED  C3326.
      • 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 .
    • Measure the resistance between DCSM  C3036c-4, circuit VHS21 (BU/WH), harness side and backrest TED  C3326-7, circuit VHS21 (BU/WH), harness side.
      Fig 3: Measuring Resistance Between DCSM C3036c-4 And Backrest TED C3326-7
      G06076962Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
  9. AS9 CHECK THE BLOWER CIRCUIT RHS08 (VT/WH) FOR A SHORT TO VOLTAGE 
    • Ignition ON.
    • Measure the voltage between DCSM  C3036c-7, circuit RHS08 (VT/WH), harness side and ground.
      Fig 4: Measuring Voltage Between DCSM C3036c-7, Circuit RHS08 (VT/WH), Harness Side And Ground
      G06134450Courtesy of FORD MOTOR CO.
    • Is any voltage present? 
  10. AS10 CHECK THE BLOWER CIRCUIT CHS08 (BN/YE) FOR A SHORT TO GROUND 
    • Ignition OFF.
    • Measure the resistance between DCSM  C3036c-8, circuit CHS08 (BN/YE), harness side and ground.
      Fig 5: Measuring Resistance Between DCSM C3036c-8, Circuit CHS08 (BN/YE), Harness Side And Ground
      G06134407Courtesy of FORD MOTOR CO.
    • Is the resistance greater than 10,000 ohms? 
  11. AS11 CHECK THE BLOWER CIRCUITS RHS08 (VT/WH) AND CHS08 (BN/YE) FOR AN OPEN 
    • Measure the resistance between:
      • DCSM  C3036c-8, circuit CHS08 (BN/YE), harness side and backrest TED  C3326-2, circuit CHS08 (BN/YE), harness side.
      • DCSM  C3036c-7, circuit RHS08 (VT/WH), harness side and backrest TED  C3326-4, circuit RHS08 (VT/WH), harness side.
        Fig 6: Measuring Resistance Between DCSM C3036c-8, Circuit CHS08 (BN/YE) And Cushion TED C3328-2, Circuit CHS08 (BN/YE)
        G06077029Courtesy of FORD MOTOR CO.
    • Are the resistances less than 5 ohms? 
  12. AS12 CHECK THE BLOWER RESISTANCE 
      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  C3326 pin 2 and pin 4, component side.
      Fig 7: Measuring Resistance Between Cushion TED C3327 Pin 2 And Pin 4, Component Side
      G06077017Courtesy of FORD MOTOR CO.
    • Is the resistance between 4,000 ohms and 10,000 ohms? 
  13. AS13 CHECK THE BLOWER SPEED CONTROL RESISTANCE 
      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  C3326 pin 7 and pin 4, component side.
      Fig 8: Measuring Resistance Between Cushion TED C3328 Pin 7 And Pin 4, Component Side
      G06076991Courtesy of FORD MOTOR CO.
    • Is the resistance between 240,000 ohms and 420,000 ohms? 
  14. AS14 CHECK THE TED INSTALLATION AND FOR CRUSHED SEAT BACKREST 
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