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Home >> Jeep >> 2007 >> Wrangler X, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> DTCS P0642 To P1602 >> P1115-General Temperature Rationality >> Diagnostic Test
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Diagnostic Test

  1. 1) ACTIVE DTC 

    Turn the ignition off.

    If possible, allow the vehicle to sit with the ignition off for more than 480 minutes in an environment where the temperature is consistent and above -7° C (19.4° F).

    Test drive the vehicle. The vehicle must exceed 48 km/h (30 mph) during the test drive. Do not cycle the ignition off when the test drive is completed.

    With a scan tool, select View the DTCs.

    NOTE: All ECT, Intake Air, and Ambient Air Temperature Sensor codes must be diagnosed and repaired before continuing.
    NOTE: In cold weather, this DTC could be set by a high powered block heater and no repair would be required.

    Is the DTC Active or Pending at this time? 

    Yes 

    1. Go to  2).

    No 

    1. Refer to INTERMITTENT CONDITION .
  2. 2) TEMPERATURE SENSOR CIRCUIT 

    With a scan tool, read the ECT, Ambient Air Temp, and Intake Air Temp Sensor temp values.

    Start the engine.

    Allow the engine to reach normal operating temperature while monitoring the three Sensor temperature values.

    Is the temperature for each of the Sensors increasing properly? 

    Yes 

    1. Refer to INTERMITTENT CONDITION .

    No 

    1. Go to  3).
  3. 3) TEMPERATURE SENSOR 
    Fig 1: Identifying Ambient Air Temperature Sensor Connector Terminals
    GC0002646Courtesy of CHRYSLER LLC
    Fig 2: Checking ECT Sensor Harness Connector
    GC0059435Courtesy of CHRYSLER LLC
    Fig 3: Checking Intake Air Temperature Sensor
    GC0062058Courtesy of CHRYSLER LLC

    Disconnect the suspected sensor.

    Ignition on, engine not running.

    With the scan tool, read the voltage of the suspected Sensor.

    Connect a jumper wire between the Sensor Signal circuit and the Sensor ground circuit.

    Did the voltage reading start at 4.8 to 5.0 volts and decrease to 0 volts when the jumper wire was installed? 

    Yes 

    1. Verify that there is good pin to terminal contact in the related Sensor and Powertrain Control Module connectors. Replace the Sensor if no problems were found in the connectors.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go to  4).
      NOTE: Remove the jumper wire before continuing.
  4. 4) EXCESSIVE RESISTANCE IN THE TEMPERATURE SENSOR SIGNAL CIRCUIT 
    Fig 4: Identifying PCM & TIPM Harness Connectors
    GC0062054Courtesy of CHRYSLER LLC
    Fig 5: Checking Sensor Signal Circuit And PCM
    GC0059437Courtesy of CHRYSLER LLC
    Fig 6: Measuring Resistance Of AAT Sensor Signal Circuit
    GC0062063Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Disconnect the C2 PCM harness connector.

    Disconnect the C4 TIPM harness connector.

    CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

    Measure the resistance of the Sensor Signal circuit from the Sensor harness connector to the appropriate terminal of special tool #8815 for the ECT Sensor and IAT Sensor.

    Measure the resistance of the (G31) AAT Sensor Signal circuit from the Sensor harness connector to the C4 TIPM harness connector.

    Is the resistance above 5.0 ohms. 

    Yes 

    1. Repair the excessive resistance in the Temperature Sensor Signal circuit.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go to  5).
  5. 5) EXCESSIVE RESISTANCE IN THE SENSOR GROUND CIRCUIT 
    Fig 7: Checking Sensor Ground Circuit And TIPM
    GC0062055Courtesy of CHRYSLER LLC
    Fig 8: Measuring Resistance Of Sensor Ground Circuit
    GC0059438Courtesy of CHRYSLER LLC
    Fig 9: Measuring Resistance Of Sensor Ground Circuit
    GC0062064Courtesy of CHRYSLER LLC

    Measure the resistance of the (K900) Sensor ground circuit from the ECT Sensor and IAT Sensor to the appropriate terminal of special tool #8815.

    Measure the resistance of the (G931) Sensor ground circuit from the AAT Sensor harness connector to the C4 TIPM harness connector.

    Is the resistance above 5.0 ohms. 

    Yes 

    1. Repair the excessive resistance in the Sensor ground circuit.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go to  6).
  6. 6) SENSOR SIGNAL CIRCUIT SHORTED TO GROUND 
    Fig 10: Measuring Resistance Between Ground And ECT Signal Circuit
    GC0059439Courtesy of CHRYSLER LLC
    Fig 11: Measuring Resistance Between Ground And Sensor Signal Circuit
    GC0062060Courtesy of CHRYSLER LLC
    Fig 12: Checking Ambient Air Temperature Sensor Signal Circuit Shorted To Ground
    GC0002648Courtesy of CHRYSLER LLC

    Measure the resistance between ground and the Sensor Signal circuit at the Sensor harness connector.

    Is the resistance below 100 ohms? 

    Yes 

    1. Repair the short to ground in the Sensor Signal circuit.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go to  7).
  7. 7) SENSOR SIGNAL CIRCUIT SHORTED TO THE SENSOR GROUND CIRCUIT 
    Fig 13: Measuring Resistance Between ECT Signal Circuit
    GC0059440Courtesy of CHRYSLER LLC
    Fig 14: Measuring Resistance Between Ground And Sensor Signal Circuit
    GC0062062Courtesy of CHRYSLER LLC
    Fig 15: Checking AAT Sensor Signal Circuit Shorted To Ground
    GC0002647Courtesy of CHRYSLER LLC

    Measure the resistance between ground and the Sensor Signal circuit at the Sensor harness connector.

    Is the resistance below 100 ohms? 

    Yes 

    1. Repair the short between the Sensor ground circuit and the Sensor Signal circuit.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go to  8).
  8. 8) SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE 
    Fig 16: Measuring Voltage On ECT Signal Circuit
    GC0059436Courtesy of CHRYSLER LLC
    Fig 17: Measuring Voltage On Sensor Signal Circuit
    GC0062059Courtesy of CHRYSLER LLC
    Fig 18: Checking Ambient Air Temperature Sensor Signal Circuit Shorted To Battery Voltage
    GC0002645Courtesy of CHRYSLER LLC

    Turn the ignition on.

    Measure the voltage on the Sensor Signal circuit at the Sensor harness connector.

    Is there any voltage present? 

    Yes 

    1. Repair the short to voltage in the Sensor Signal circuit.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go to  9).
  9. 9) POWERTRAIN CONTROL MODULE (PCM) 

    Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the related Sensor and the Powertrain Control Module (PCM).

    Look for any chafed, pierced, pinched, or partially broken wires.

    Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related Sensor and Powertrain Control Module connectors.

    Refer to any Technical Service Bulletins that may apply.

    Were there any problems found? 

    Yes 

    1. Repair as necessary.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Replace and program the Powertrain Control Module per Service Information.
    2. Perform POWERTRAIN VERIFICATION TEST .