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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1870 (Engine Controls And Fuel - 3.5L (L66) - DTC P2227 To DTC P2649) >> DTC P2646 >> 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 on 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. 3:  This step checks for a short to ground in the oil pressure switch signal circuit. A DTC P2647 will set if the signal circuit is not shorted to ground.
  3. 4:  This step checks the operation of the rocker arm oil control solenoid. When commanded ON, oil pressure should increase to at least 392 kPa (56 psi).
  4. 6:  This step tests the operation of the rocker arm oil pressure switch. The oil pressure switch is normally closed to ground with less than 48 kPa (7 psi) of oil pressure. With the oil control solenoid energized oil pressure will open the switch and the scan tool should indicate ON.
  5. 11:  After replacing the PCM, the relationship between the crankshaft position (CKP) sensor and the crankshaft must be re-established. A new minimum throttle position and idle speed must also be established.
DTC P2646

Step Action Values Yes No
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
  1. Turn OFF the ignition.
  2. Disconnect the rocker arm oil control solenoid.
  3. Measure the resistance of the solenoid with a DMM.
Is the resistance within the specified range?		 14-30 Ω at 20°C (68°F) Go to Step 3  Go to Step 10 
3 
  1. Turn ON the ignition, with the engine OFF.
  2. Leave the rocker arm oil control solenoid disconnected.
  3. Clear any DTCs with the scan tool.
  4. Wait 10 seconds and check for DTCs.
Did a DTC P2647 set?		 - Go to Step 4  Go to Step 8 
4 
  1. Remove the oil pressure switch.
  2. Install the EN 46332  Oil Pressure Gage Adapter to the engine. See Special Tools .
  3. Install the oil pressure gage from the SA9127E  Bar Gage Set to the adapter.
  4. Install the oil pressure switch to the adapter.
  5. Start and run the engine until the coolant temperature is 85°C (185°F).
  6. Increase the engine speed to 2,800 RPM.
  7. Command the intake rocker arm actuator solenoid ON with the scan tool. Refer to Scan Tool Output Controls .
Is the oil pressure more than the specified value?		 392 kPa (56 psi) Go to Step 6  Go to Step 5 
5
  1. Turn OFF the ignition.
  2. Remove the rocker arm oil control solenoid. Refer to Rocker Arm Oil Control Solenoid Valve Replacement .
  3. Inspect for any of the following conditions:
    • A stuck or binding spool valve
    • A restriction or blockage in the oil passages
  4. Repair any condition as necessary.
Did you find and correct a condition?		 - Go to Step 12  Go to Step 9 
6 
  1. Observe the intake rocker arm actuator oil pressure switch parameter on the scan tool.
  2. Increase the engine speed to 2,800 RPM.
  3. Command the rocker actuator solenoid ON with the scan tool.
Did the oil pressure switch indicate ON when the solenoid was commanded ON?		 - Go to Intermittent Conditions Go to Step 6 
7
  1. Disconnect the electrical connector of the rocker arm oil pressure switch.
  2. Connect a DMM to the signal circuit of the oil pressure switch and ground.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the DC voltage.
Is the voltage more than the specified value?		 6.9 V Go to Step 10  Go to Step 8 
8
  1. Inspect for a short to ground in the signal circuit of the rocker arm oil pressure switch.
  2. Repair as necessary. Refer to Wiring Repairs .
Did you find and correct a condition?		 - Go to Step 12  Go to Step 11 
9 Replace the rocker arm oil control solenoid valve. Refer to Rocker Arm Oil Control Solenoid Valve Replacement .
Did you complete the replacement?		 - Go to Step 12  -
10 Replace the rocker arm oil pressure switch. Refer to Rocker Arm Oil Pressure Switch Replacement .
Did you complete the replacement?		 - Go to Step 12  -
11 
  1. Replace the powertrain control module (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 12  -
12
  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.
Does the DTC run and pass?		 - Go to Step 13  Go to Step 2 
13 With a scan tool, observe the stored information, Capture Info.
Does the scan tool display any DTCs that you have not diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List - Vehicle System OK
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