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Home >> Mercury >> 2010 >> Milan Base, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 1199 (HVAC - Climate Control System - General Information And Diagnostics - (Except Hybrid)) >> Diagnosis And Testing >> Climate Control System >> Pinpoint Tests >> Pinpoint Test C: DTC B1251 or B1253 >> Pinpoint Test C: DTC B1251 Or B1253

Pinpoint Test C: DTC B1251 Or B1253

WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
  1. C1 CHECK THE SENSOR RESISTANCE 
    • Ignition OFF.
    • Disconnect: In-Vehicle Temperature Sensor C233.
    • Measure the resistance between in-vehicle temperature sensor C233 terminals.
      Fig 1: Measuring Resistance Between In-Vehicle Temperature Sensor Terminals
      G06075208Courtesy of FORD MOTOR CO.
    • Is the resistance within the specified values for these temperature ranges: 10-20°C (50-68°F), 37,000-58,000 ohms; 20-30°C (68-86°F), 24,000-37,000 ohms; 30-40°C (86-104°F), 16,000-24,000 ohms? 
    • Yes:  GO to C2  .
    • No:  INSTALL a new in-vehicle temperature sensor. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  2. C2 CHECK THE SENSOR OUTPUT VOLTAGE 
    • Ignition ON.
    • Press the AUTO button.
    • Measure the voltage between in-vehicle temperature sensor C233-1, circuit VH414 (GN/BU), harness side and C233-2, circuit RH111 (GY/BU), harness side.
      Fig 2: Measuring Voltage Between In-Vehicle Temperature Sensor C233-1, Circuit VH414 (GN/BU) And C233-2
      G06064527Courtesy of FORD MOTOR CO.
    • Is the voltage between 4.7 and 5.1 volts? 
    • Yes:  INSTALL a new in-vehicle sensor. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. If code returns, GO to  C7.
    • No : For DTC B1251  , GO to C3  .

      For DTC B1253  , GO to  C5.

  3. C3 CHECK CIRCUIT VH414 (GN/BU) FOR AN OPEN 
    • Ignition OFF.
    • Disconnect: HVAC Module - DATC  C2356A.
    • Measure the resistance between HVAC module - DATC  C2356B-23, circuit VH414 (GN/BU), harness side and in-vehicle temperature sensor C233-1, circuit VH414 (GN/BU), harness side.
      Fig 3: Measuring Resistance Between HVAC Module - DATC C2356B-23 And In-Vehicle Temperature Sensor C233-1
      G06098547Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    • Yes:  GO to C4  .
    • No:  REPAIR circuit VH414 (GN/BU) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  4. C4 CHECK CIRCUIT RH111 (GY/BU) FOR AN OPEN 
    • Measure the resistance between HVAC module - DATC  C2356A-10, circuit RH111 (GY/BU), harness side and in-vehicle temperature sensor C233-2, circuit RH111 (GY/BU), harness side.
      Fig 4: Measuring Resistance Between HVAC Module Circuit RH111 (GY/BU), Harness Side And In-Vehicle Temperature Sensor C233-2
      G06064530Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    • Yes:  GO to  C7.
    • No:  REPAIR circuit RH111 (GY/BU) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  5. C5 CHECK CIRCUIT VH414 (GN/BU) FOR A SHORT TO CIRCUIT RH111 (GY/BU) 
    • Ignition OFF.
    • Disconnect: HVAC Module - DATC  C2356B.
    • Measure the resistance between in-vehicle temperature sensor C233-1, circuit VH414 (GN/BU), harness side and C233-2, circuit RH111 (GY/BU), harness side.
      Fig 5: Measuring Resistance Between In-Vehicle Temperature Sensor C233-1 And C233-2
      G06064531Courtesy of FORD MOTOR CO.
    • Is the resistance greater than 10,000 ohms? 
    • Yes:  GO to C6  .
    • No:  REPAIR circuit VH414 (GN/BU) for a short to circuit RH111 (GY/BU). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  6. C6 CHECK CIRCUIT VH414 (GN/BU) FOR A SHORT TO GROUND 
    • Measure the resistance between HVAC module - DATC  C2356B-23, circuit VH414 (GN/BU), harness side and ground.
      Fig 6: Measuring Resistance Between HVAC Module - DATC C2356B-23 And Ground
      G06098550Courtesy of FORD MOTOR CO.
    • Is the resistance greater than 10,000 ohms? 
    • Yes:  GO to C7  .
    • No:  REPAIR circuit VH414 (GN/BU) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  7. C7 CHECK THE HVAC MODULE CONNECTION 
    • Inspect the HVAC module connectors for:
      • corrosion.
      • pushed-out terminals.
      • damaged terminals.
    • Connect and correctly seat all the HVAC module connectors.
    • Clear the DTCs.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
    • Yes:  INSTALL a new HVAC module. REFER to CLIMATE CONTROL . TEST the system for normal operation.
    • No:  The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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