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.

ECT SENSOR
1. Turn the ignition on, engine not running.
2. With the scan tool, read ECT Sensor voltage.
3. Carefully tap on or near the ECT Sensor while monitoring the ECT Sensor voltage reading on the scan tool.
  NOTE:
  The sensor voltage should not change more than 0.5 volts.
  
  Does the voltage change more than 0.5 volts?
  
  Yes
  - Verify that there is good pin to terminal contact in the ECT Sensor and Powertrain Control Module connectors. If OK, replace the Engine Coolant Temperature Sensor. Refer to SENSOR, COOLANT TEMPERATURE, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 2
CHECK THE (K2) ECT SIGNAL CIRCUIT FOR AN INTERMITTENT SHORT TO VOLTAGE
NOTE:
This DTC will set due to an intermittent condition. Due to this condition it is recommended to wiggle test the wiring related to the ECT Sensor during testing in all of the following steps.
1. Turn the ignition off.
2. Disconnect the ECT Sensor harness connector.
3. Turn the ignition on, engine not running.
4. Measure the voltage between ground and the (K2) ECT Sensor Signal circuit at the ECT Sensor harness connector.
  Is the voltage reading above 5.2 volts at any time while wiggle testing the harness?
  
  Yes
  - Repair the (K2) ECT Sensor Signal circuit for a short to voltage.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 3
CHECK THE (K2) ECT SIGNAL CIRCUIT FOR AN INTERMITTENT OPEN
1. Turn the ignition off.
2. Disconnect the PCM C2 harness connector.
3. Measure the resistance of the (K2) ECT Sensor Signal circuit between the ECT Sensor harness connector and the PCM C2 harness connector.
  Does the resistance go above 5.0 Ohms at any time while wiggle testing the harness?
  
  Yes
  - Go To 4
  No
  - Repair the (K2) ECT Sensor Signal circuit for an intermittent open circuit.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK THE (K900) SENSOR GROUND CIRCUIT FOR AN INTERMITTENT OPEN
1. Measure the resistance of the (K900) Sensor Ground circuit from the ECT Sensor harness connector to the appropriate terminal of the PCM harness connector.
  Does the resistance go above 5.0 Ohms at any time while wiggle testing the harness?
  
  Yes
  - Go To 5
  No
  - Repair the (K900) Sensor ground circuit for an intermittent open circuit.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
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.