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DTC Troubleshooting

DIAGNOSIS PROCEDURE - DTC P0125 INSUFFICIENT ENGINE COOLANT TEMPERATURE FOR CLOSED LOOP

Step Action Value(s) Yes No
1 Perform an On-Board Diagnostic (OBD II) System Check.
Is the check complete?		 - Go to Step 2. Go to "ON-BOARD DIAGNOSTIC (OBD II) SYSTEM CHECK ".
2
  1. Allow the engine to cool fully to ambient temperature.
  2. Turn the ignition switch to ON with the engine OFF.
  3. Install a scan tool.
  4. Compare the Engine Coolant Temperature (ECT) sensor reading to the Intake Air Temperature (IAT) sensor readings.

Are the temperature readings close?		 - Go to Step 4. Go to Step 3.
3
  1. Disconnect the ECT sensor electrical connector.
  2. Using a Digital Voltmeter (DVM), measure the resistance across the ECT sensor terminals 1 and 2.
  3. Check the ECT sensor value to actual coolant temperature using the Temperature vs. Resistance table.

Does the ECT sensor accurately reflect the actual engine coolant temperature?		 - Go to Step 4. Go to Step 9.
4 Disconnect the ECT sensor electrical connector.
Is the ECT sensor value less than the specified value?		 5V Go to Step 8. Go to Step 5.
5 Jumper the ECT sensor signal circuit, terminal 1 and the sensor ground circuit, terminal 2 together at the ECT sensor connector.
Is the ECT sensor value greater than the specified value?		 0V Go to Step 7. Go to Step 6.
6 Check for proper cooling system operation and repair as necessary.
Is a repair necessary?		 - Go to Step 10. Go to "DIAGNOSTIC AIDS "
7 Check the ECT sensor electrical connector terminals 2 and 1 and the engine control module (ECM) electrical connector terminals 71 and 36 for poor connectors or malfunctioning terminals and repair as necessary.
Is a repair necessary?		 - Go to Step 10. Go to Step 8.
8
  1. Turn the ignition OFF.
  2. Replace the ECM.

Is the action complete?		 - Go to Step 10. -
9 Replace the ECT sensor.
Is the action complete?		 - Go to Step 10. -
10
  1. Using the scan tool, clear the Diagnostic Trouble Codes (DTCs).
  2. Start the engine and idle at normal operating temperature.
  3. Operate the vehicle within the conditions for setting this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic ran and passed?		 - Go to Step 11. Go to Step 12.
11 Check if any additional DTCs are set.
Are any DTCs displayed that have not been diagnosed?		 - Go to applicable DTC TABLE . System OK
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