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Home >> Mercury >> 2008 >> Milan Base, 2.3 Z, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 1354 (HVAC Climate Control System - General Information And Diagnostics) >> Diagnostic Tests >> Climate Control System >> Pinpoint Tests >> Pinpoint Test B: DTC P0537 or P0538 >> Pinpoint Test B: DTC P0537 Or DTC P0538

Pinpoint Test B: DTC P0537 Or DTC P0538

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.
  1. B1 CHECK THE SENSOR RESISTANCE 
    • Key in OFF position.
    • Disconnect: Evaporator Discharge Temperature Sensor C2295
    • Carry out the Temperature Sensor - Evaporator Discharge .
    • Is the resistance within the specified values for the temperatures? 
    1. YES  : Go to  B2.
    2. NO  : INSTALL a new in-vehicle temperature sensor. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  2. B2 CHECK THE HVAC MODULE OUTPUT VOLTAGE 
    • Key in ON position.
    • Press the AUTO button.
      • Fig 1: Checking EATC Sensor Output Voltage
      GF0030250Courtesy of FORD MOTOR CO.
    • Measure the voltage between evaporator discharge temperature sensor C2295-2, circuit VH406 (VT/BN), harness side and C2295-1, circuit RE407 (YE/VT), harness side.
    • Is the voltage between 4.7 and 5.1 volts? 
    1. YES  : INSTALL a new evaporator discharge sensor. If code returns, go to  B7.
    2. NO  : If diagnosing DTC P0538, go to  B3.

      If diagnosing DTC P0537, go to  B5.

  3. B3 CHECK CIRCUIT VH406 (VT/BN) FOR AN OPEN 
    • Key in OFF position.
    • Disconnect: PCM C175b
      • Fig 2: Checking Circuit VH406 (VT/BN) For An Open
      GF0041546Courtesy of FORD MOTOR CO.
    • Measure the resistance between PCM C175b-53, circuit VH406 (VT/BN), harness side and evaporator discharge temperature sensor C2295-2, circuit VH406 (VT/BN), harness side.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  B4.
    2. NO  : REPAIR circuit VH406 (VT/BN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  4. B4 CHECK CIRCUIT RE407 (YE/VT) FOR AN OPEN 
      Fig 3: Checking Circuit RE407 (YE/VT) For An Open
      GF0041547Courtesy of FORD MOTOR CO.
    • Measure the resistance between PCM C175b-58, circuit RE407 (YE/VT), harness side and evaporator discharge temperature sensor C2295-1, circuit RE407 (YE/VT), harness side.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  B7.
    2. NO  : REPAIR circuit RE407 (YE/VT) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  5. B5 CHECK CIRCUITS VH406 (VT/BN) AND RE407 (YE/VT) FOR A SHORT TOGETHER 
    • Key in OFF position.
    • Disconnect: PCM C175b
      • Fig 4: Checking Circuit VH406 (VT/BN) For A Short To Circuit RH104 (BU/BN)
      GF0030253Courtesy of FORD MOTOR CO.
    • Measure the resistance between evaporator discharge temperature sensor C2295-2, circuit VH406 (VT/BN), harness side and C2295-1, circuit RE407 (YE/VT), harness side.
    • Is the resistance greater than 10,000 ohms? 
    1. YES  : Go to  B6.
    2. NO  : REPAIR circuits VH406 (VT/BN) and RE407 (YE/VT) for a short together. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  6. B6 CHECK CIRCUIT VH406 (VT/BN) FOR A SHORT TO GROUND 
      Fig 5: Checking Circuit VH406 (VT/BN) For A Short To Ground
      GF0041548Courtesy of FORD MOTOR CO.
    • Measure the resistance between PCM C175b-53, circuit VH406 (VT/BN), harness side and ground.
    • Is the resistance greater than 10,000 ohms? 
    1. YES  : Go to  B7.
    2. NO  : REPAIR circuit VH406 (VT/BN) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  7. B7 CHECK THE PCM CONNECTION 
    • Clear the DTCs.
    • Disconnect all the PCM connectors.
    • Check for:
      • corrosion.
      • pushed-out pins.
      • incorrectly seated connector.
    • Connect and correctly seat all the PCM connectors.
    • Operate the system.
    • Does the concern return? 
    1. YES  : INSTALL a new PCM. TEST the system for normal operation.
    2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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