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Pinpoint Test Ax: DTC B2729

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. AX1 CHECK THE DCSM FOR DTCs 
    • Enter the following diagnostic mode on the scan tool: Self Test - DCSM  .
    • Was DTC B2729 retrieved during the self-test? 
    • Yes:  GO to AX2  .
    • No:  GO to  AX4.
  2. AX2 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: Driver Seat Side Air Bag C328.
    • Disconnect: Passenger Seat Side Air Bag C327.
    • Disconnect: DCSM  C3036b.
    • Disconnect: Cushion TED  C3327.
      • 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  C3036b-7, circuit VHS26 (VT), harness side and ground.
      • DCSM  C3036b-8, circuit RHS05 (YE/VT), harness side and ground.
        Fig 1: Measuring Resistance Between DCSM C3036b-7, Circuit VHS26 (VT), Harness Side And Ground
        G06134439Courtesy of FORD MOTOR CO.
    • Are the resistances greater than 10,000 ohms? 
    • Yes:  GO to AX3  .
    • No:  REPAIR the affected circuit. REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable.

      CONNECT passenger seat side air bag module C327.

      CONNECT driver seat side air bag module C328.

      REPOWER the SRS  . REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .

  3. AX3 CHECK THE TED THERMISTOR 
    • Measure the resistance between cushion TED  C3327 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. AX4 CONFIRM THE FAULT 
    • Verify with the customer that the concern is the seat shuts OFF in heat mode.
      • NOTE: A crushed seat cushion 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 driver 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 AX5  .
    • 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. AX5 CHECK OPERATION OF THE SEAT 
    • With the engine running, set both front seats to HIGH cool (3 LEDs illuminated on HVAC module).
    • Compare the airflow from the driver seat cushion and compare it to the airflow from the passenger seat cushion.
    • Is the airflow exhausting from the driver seat cushion comparable to the airflow exhausting from the passenger seat cushion? 
    • Yes:  GO to  AX14.
    • No:  GO to AX6  .
  6. AX6 CHECK THE CUSHION BLOWER FOR AN OBSTRUCTION OR RESTRICTED FILTER 
    • Ignition OFF.
    • Inspect the blower of the cushion 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 AX7  .
  7. AX7 CHECK THE CUSHION FAN OPERATION 
    • Ignition ON.
    • With the engine running, set both front seats to HIGH cool (3 LEDs illuminated on HVAC module).
    • Inspect the cushion blower for operation.
    • Does the cushion blower operate? 
    • Yes:  GO to  AX14.
    • No:  GO to AX8  .
  8. AX8 CHECK THE BLOWER SPEED CONTROL CIRCUIT FOR AN OPEN 
    • Ignition OFF.
    • Depower the SRS  . Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
    • Disconnect: Driver Seat Side Air Bag C328.
    • Disconnect: Passenger Seat Side Air Bag C327.
    • Disconnect: DCSM  C3036c.
    • Disconnect: Cushion TED  C3327.
    • Measure the resistance between DCSM  C3265c-11, circuit VHS18 (BN/GN), harness side and cushion TED  C3327-7, circuit VHS18 (BN/GN), harness side.
      Fig 3: Measuring Resistance Between DCSM C3265c-11 And Cushion TED C3327-7
      G06077034Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    • Yes:  GO to AX9  .
    • No:  REPAIR the circuit. REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable.

      CONNECT passenger seat side air bag module C327.

      CONNECT driver seat side air bag module C328.

      REPOWER the SRS  . REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .

  9. AX9 CHECK BLOWER CIRCUIT RHS03 (GY/OG) FOR A SHORT TO VOLTAGE 
      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 .
    • Ignition ON.
    • Measure the voltage between DCSM  C3036c-15, circuit RHS03 (GY/OG), harness side and ground.
      Fig 4: Measuring Voltage Between DCSM C3036c-15, Circuit RHS03 (GY/OG), Harness Side And Ground
      G06077035Courtesy of FORD MOTOR CO.
    • Is any voltage present? 
    • Yes:  REPAIR the circuit. REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable.

      CONNECT passenger seat side air bag module C327.

      CONNECT driver seat side air bag module C328.

      REPOWER the SRS  . REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .

    • No:  GO to AX10  .
  10. AX10 CHECK BLOWER CIRCUIT CHS03 (GN/BN) FOR A SHORT TO GROUND 
    • Ignition OFF.
    • Measure the resistance between DCSM  C3036c-16, circuit CHS03 (GN/BN), harness side and ground.
      Fig 5: Measuring Resistance Between DCSM C3036c-16, Circuit CHS03 (GN/BN), Harness Side And Ground
      G06077036Courtesy of FORD MOTOR CO.
    • Is the resistance greater than 10,000 ohms? 
    • Yes:  GO to AX11  .
    • No:  REPAIR the circuit. REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable.

      CONNECT passenger seat side air bag module C327.

      CONNECT driver seat side air bag module C328.

      REPOWER the SRS  . REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .

  11. AX11 CHECK BLOWER CIRCUITS RHS03 (GY/OG) AND CHS03 (GN/BN) FOR AN OPEN 
    • Measure the resistance between:
      • DCSM  C3036c-16, circuit CHS03 (GN/BN), harness side and cushion TED  C3327-2, circuit CHS03 (GN/BN), harness side.
      • DCSM  C3036c-15, circuit RHS03 (GY/OG), harness side and cushion TED  C3327-4, circuit RHS03 (GY/OG), harness side.
        Fig 6: Measuring Resistance Between DCSM C3036c-16, Circuit CHS03 (GN/BN) And Cushion TED C3327-2, Circuit CHS03 (GN/BN)
        G06077025Courtesy of FORD MOTOR CO.
    • Are the resistances less than 5 ohms? 
    • Yes:  GO to AX12  .
    • No:  REPAIR the affected circuit. REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable.

      CONNECT passenger seat side air bag module C327.

      CONNECT driver seat side air bag module C328.

      REPOWER the SRS  . REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .

  12. AX12 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 cushion TED  C3327 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. AX13 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 cushion TED  C3327 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. AX14 CHECK THE TED INSTALLATION AND FOR CRUSHED SEAT CUSHION 
    • Ignition OFF.
    • Remove the seat. Refer to SEAT - FRONT .
    • Remove the seat cushion cover. Refer to SEAT CUSHION COVER - FRONT .
    • Inspect the seat cushion for the following:
      • Is the TED  correctly installed?
      • Is the seat cushion 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? 
    • Yes:  CONNECT the battery ground cable.

      INSTALL a new DCSM  . 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 C327.

      CONNECT driver seat side air bag module C328.

      REPOWER the SRS  . REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .

    • No:  CORRECTLY install the cushion TED  or INSTALL a new seat cushion foam pad and/or climate controlled seat manifold. INSTALL the driver seat. CONNECT the battery ground cable. REPEAT the self-test. CLEAR the DTCs.

      DISCONNECT the battery ground cable.

      CONNECT passenger seat side air bag module C327.

      CONNECT driver seat side air bag module C328.

      REPOWER the SRS  . REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .

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