Diagnostic Test

WARNING: This page is about a different car, the 2015 Fiat 500. However, it is still accessible from the selected car via links, so may be relevant.

ENGINE COOLANT TEMPERATURE
1. Turn the ignition off.
2. Allow the vehicle to sit with the ignition off for more than 480 minutes in an environment where the temperature is consistent and above -64°C (-83°F), or 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 10°C (18°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.
4. Measure the resistance of the (K2) ECT Signal circuit between the ECT Sensor harness connector and the PCM C2 harness connector.
  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 (K900) SENSOR GROUND CIRCUIT
1. Measure the resistance of the (K900) Sensor Ground circuit between the ECT Sensor harness connector and the PCM C2 harness connector.
  Is the resistance below 3.0 Ohms?
  
  Yes
  - Go To 4
  No
  - Repair the (K900) Sensor ground circuit for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
ECT SENSOR VOLTAGE
1. Turn the ignition off.
2. Reconnect the PCM C2 harness connector.
3. Turn the ignition on.
4. 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.
5. Connect a jumper between the (K2) ECT Signal circuit and the (K900) Sensor Ground circuit at the ECT 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 Engine Coolant Temperature Sensor in accordance with the Service Information. Refer to SENSOR, COOLANT TEMPERATURE, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 5
CHECK RELATED PCM AND COMPONENT CONNECTIONS
1. Perform any Service Bulletins that apply.
2. Disconnect all PCM harness connectors.
3. Disconnect all related in-line harness connections (if equipped).
4. Disconnect the related component harness connectors.
5. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
  - Proper connector installation.
  - Damaged connector locks.
  - Corrosion.
  - Other signs of water intrusion.
  - Weather seal damage (if equipped).
  - Bent terminals.
  - Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
  - Terminals that have been pushed back into the connector cavity.
  - Check for spread terminals and verify proper terminal tension.
  Repair any conditions that are found.
6. Reconnect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
7. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
9. With the scan tool, erase DTCs.
10. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
11. With the scan tool, read DTCs.
  Did the DTC return?
  
  Yes
  - Replace the Powertrain Control Module in accordance with the Service information. Refer to MODULE, POWERTRAIN CONTROL, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  - Test complete.