Diagnostic Test

ENGINE COOLANT TEMPERATURE
1. Turn the ignition off.
2. Allow the vehicle to sit with the ignition off in an environment where the temperature is consistent and above -64°C (-83°F) until the engine coolant temperature is equal to ambient temperature.
3. Turn the ignition on.
4. With the scan tool, compare the AAT, ECT and IAT sensor values.
  Is the Engine Coolant Temperature Sensor value within 15°C (59°F) of the other two sensor values?
  
  Yes
  - Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
  No
  - Go To 2
CHECK FOR EXCESSIVE RESISTANCE IN THE (K2) ECT SIGNAL CIRCUIT
1. Turn the ignition off.
2. Disconnect the ECT Sensor harness connector.
3. Disconnect the PCM C2 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 the GPEC Diagnostic Adaptor to perform the diagnosis.
4. Connect the (special tool #10436, Adapter, GPEC Diagnostic).
5. Measure the resistance of the (K2) ECT Signal circuit between the ECT Sensor harness connector and the GPEC Adaptor.
  Is the resistance below 3.0 Ohms?
  
  Yes
  - Go To 3
  No
  - Repair the (K2) ECT Signal circuit for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK FOR EXCESSIVE RESISTANCE IN THE (K915) SENSOR GROUND CIRCUIT
1. Measure the resistance of the (K915) Sensor Ground circuit between the ECT Sensor harness connector and the GPEC Adaptor.
  Is the resistance below 3.0 Ohms?
  
  Yes
  - Go To 4
  No
  - Repair the (K915) Sensor ground circuit for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
ECT SENSOR VOLTAGE
1. Reconnect the PCM C2 harness connector.
2. Turn the ignition on.
3. With the scan tool, read the ECT Sensor voltage.
  NOTE:
  The sensor voltage should be approximately 5.0 volts (plus or minus 0.1 volts) with the connector disconnected.
4. Connect a jumper between the (K2) ECT Signal circuit and the (K915) Sensor Ground circuit AT the Engine Coolant Temperature Sensor harness connector.
  NOTE:
  The sensor voltage should be approximately 0.0 volts (plus or minus 0.1 volts) with the jumper in place.
  
  Does the scan tool display the voltage as described above?
  
  Yes
  - Replace the ECT Sensor in accordance with the Service Information. Refer to 6.2L .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 5
POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the ECT Sensor and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the ECT Sensor and Powertrain Control Module connectors.
4. Perform any Service Bulletins that may apply.
  Were there any problems found?
  
  Yes
  - Repair as necessary.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Replace and program the Powertrain Control Module in accordance with the Service Information. Refer to MODULE, POWERTRAIN CONTROL (PCM), REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .