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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1857 (Engine Controls And Fuel - 3.5L (L66) - DTC P0030 To DTC P0222) >> DTC P0125 >> Test Description

Test Description

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers in the diagnostic table.

  1. 1:  The Diagnostic System Check - Vehicle prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
  2. 2:  This step determines if there is a cooling system malfunction.
  3. 3:  This step compares the ECT to the intake air temperature (IAT). This inspection is to be performed when the vehicle has reached the ambient room temperature. At that time both the surrounding air temperature and the engine coolant temperature are nearly equal. If the ECT sensor and circuit are OK, both sensors should indicate the same temperature.
  4. 5:  The fault not present indicates the condition that caused DTC P0125 to set is intermittent and not currently present. If no other DTCs are stored, refer to Diagnostic Aids in this test for additional information on diagnosing an intermittent DTC P0125.
  5. 10:  After replacing the PCM, the relationship between the crankshaft position (CKP) sensor and the crankshaft must re-established. A new minimum throttle position and idle speed must also be established.
DTC P0125

Step Action Value(s) Yes No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views
1  Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2  Review the list below for any of the following customer concerns:
  • Insufficient heat from the climate control system
  • The instrument panel (I/P) temperature gage indicates a lower than normal engine temperature after driving the vehicle.
  • Compare the engine coolant temperature (ECT) sensor reading to the intake air temperature (IAT) sensor reading on a scan tool.

Did you identify a customer concern from the list above?		 - Go to Step 8  Go to Step 3 
3 
  1. Allow the engine to cool to the ambient air temperature.
  2. Turn ON the ignition, leaving the engine OFF.
  3. Compare the ECT sensor reading to the IAT sensor reading on a scan tool.
Are the ECT and the IAT readings within 2 or 3 degrees of each other?		 - Go to Step 4  Go to Step 6 
4
  1. Start the engine and immediately observe the ECT on the scan tool.
  2. Continue to observe the ECT while idling the engine for 10 minutes.
Does the ECT increase by more than the specified value within the 10 minutes?		 20°C (68°F) Go to Step 5  Go to Step 8 
5  The fault is not present.
Are there any DTCs stored that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List - Vehicle Go to Diagnostic Aids In This Test
6
  1. Measure the resistance of the ECT sensor with a DMM.
  2. Compare the measured resistance of the ECT sensor with the resistance values in the Temperature vs Resistance table. Refer to Temperature Versus Resistance - Engine Coolant Temperature Sensor .
Is the resistance of the ECT sensor within specifications?		 - Go to Step 7  Go to Step 9 
7
  1. Check for any of the following conditions:
    • A high resistance in the ECT sensor signal and low reference ground circuits
    • A faulty connection at the ECT sensor
    • A faulty connection at the powertrain control module (PCM)
  2. Repair as necessary. Refer to Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 11  Go to Step 10 
8
  1. Inspect the engine cooling system for all of the following:
  2. Repair as necessary.
Did you complete the action?		 - Go to Step 11  -
9 Replace the ECT sensor. Refer to Engine Coolant Temperature Sensor Replacement .
Did you complete the replacement?		 - Go to Step 11  Go to Step 10 
10 
  1. Replace the PCM. Refer to Control Module References for replacement, setup, and programming.
  2. Perform the idle learn procedure. Refer to Idle Learn .
Did you complete the replacement?		 - Go to Step 11  -
11
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text or until the DTC P0125 diagnostic test has run.
Does the DTC run and pass?		 - Go to Step 12  Go to Step 2 
12 Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List - Vehicle System OK
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