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Pinpoint Test A: Seat Heater Mat

  1. A1: CHECK FOR DTC'S 
    1. Where possible use the manufacturer approved diagnostic system to review any logged seat heater mat DTC's

    Were any seat heater mat DTC's logged?

    • Yes  : Carry out the help text action for any logged DTC's. Clear the DTC and retest. If DTC's return follow the tests listed below GO to  A2.
    • No  : GO to  A2.
  2. A2: MANUAL CHECK 
    • The manual check should be carried out by someone familiar with correct seat heat operation
    • On full power the seat should be hot to touch
    1. If required operate the vehicle air conditioning on full for 10 minutes to reduce the in vehicle ambient temperature
    2. Operate the seat heater on full power

    Does the seat heater operate correctly?

    • Yes  : Clear any stored DTC's and retest. If seat heater operation is correct no further action required
    • No  : GO to  A3.
  3. A3: SHORT CIRCUIT TO GROUND 
    1. Refer to the electrical circuit diagrams and the seat heater mat application chart (see above) to identify the connector
    2. Disconnect the connector
    3. Refer to the electrical circuit diagrams and check the seat heater mat heater circuit  and the NTC resistor circuit  for short circuit to ground

    Are either of the circuits short circuit to ground?

    • Yes  : Repair the circuit or replace the seat heater mat as required. Refer to the warranty policy and procedures manual, or determine if any prior approval programme is in operation, prior to the installation of a new module/component. Clear any stored DTC's and retest
    • No  : GO to  A4.
  4. A4: CIRCUIT CONTINUITY TEST 
    1. Refer to the electrical circuit diagrams and check the seat heater mat (heater circuit) for circuit continuity

    Does the seat heater mat heater circuit  pass the continuity test?

    • Yes  : GO to  A5.
    • No  : Repair the circuit or replace the seat heater mat as required. Refer to the warranty policy and procedures manual, or determine if any prior approval programme is in operation, prior to the installation of a new module/component. Clear any stored DTC's and retest
  5. A5: POWER CONSUMPTION 
    NOTE: The seat heater power supply cycles on and off dependant on the seat and cabin temperature and may only switch on for 5 seconds in 30 seconds
    1. Reconnect the connector
    2. Operate the vehicle air conditioning on full for 10 minutes to reduce the in vehicle ambient temperature
    3. Refer to the electrical circuit diagrams and check the seat heater mat (heater circuit) using a current clamp 
    4. Operate the seat heater on full power
    5. Use the chart above to calculate typical value (V/R=I) (Volts  divided by Resistance  equals Current in Amps  )
    6. Examples (12 volts/0.5 ohms =24 amps) (12 volts/1 ohms = 12 amps) (12 volts/2 ohms = 6 amps)

    Does the seat heater mat consume the correct level of current?

    • Yes  : Clear any stored DTC's and retest. If operation correct, no further action required
    • No  : GO to  A6.
  6. A6: RESISTANCE CHECK 
    NOTE:
    • Ensure the multimeter used is calibrated and a resistance reading of 0  ohms is shown when the test leads are connected together, alternately subtract any resistance shown from the result
    • The seat heater mat circuits should be checked at the seat heater module connector
    • Refer to the electrical circuit diagrams and to confirm the total resistance of the circuit the cushion and backrest are connected in series
    1. Refer to the electrical circuit diagrams and the seat heater mat application chart (see above) to identify the terminals
    2. Disconnect the connector
    3. Using a multimeter, carry out a resistance check of the seat heater mat heater circuit  and the NTC resistor circuit  . Record the results
    4. Compare the results to the chart (see above)

    Are the results within specification at the given ambient temperature?

    (tolerance +/- 0.5  Ohms)

    • Yes  : Reconnect the connector. Clear any stored DTC's and retest. If customer concern or DTC's return refer to electrical circuit diagrams and investigate the power and ground supply circuits
    • No  : Replace the seat heater mat as required. Refer to the warranty policy and procedures manual, or determine if any prior approval programme is in operation, prior to the installation of a new module/component. Clear any stored DTC's and retest
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