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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 P2648 >> 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. 3:  This step checks the operation of the rocker arm oil control solenoid. With the oil control solenoid energized oil pressure will open the switch and the scan tool should indicate ON.
  3. 5:  This step checks for a short to ground in the rocker arm oil control solenoid circuit. The PCM provides a 12 volt bias signal on the solenoid control circuit that can be measured with the DMM.
  4. 8:  After replacing the PCM, a new minimum throttle position and idle speed must also be established.
DTC P2648

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. Perform the scan tool Clear DTC Information function.
  2. Start the engine.
  3. Operate the engine for 1 minute.
  4. Review the scan tool data and check for DTC P2648.
Is DTC P2648 set?		 - Go to Step 4  Go to Step 3 
3 
  1. Start the engine.
  2. Start and run the engine until the coolant temperature is 85°C (185°F).
  3. Increase the engine speed to 2,800 RPM.
  4. Observe the rocker arm actuator oil pressure switch parameter on the scan tool.
  5. Command the rocker arm oil control solenoid ON and OFF with the scan tool. Refer to Scan Tool Output Controls .
Did the oil pressure switch indicate ON when the solenoid was commanded ON and OFF when the solenoid was commanded OFF?		 - Go to Intermittent Conditions Go to Step 4 
4
  1. Disconnect the rocker arm oil control solenoid.
  2. Measure the resistance of the solenoid from the electrical terminal to the solenoid housing with a DMM.
Is the resistance within the specified range?		 14-30 Ω at 20°C (68°F) Go to Step 5  Go to Step 7 
5 
  1. Turn OFF the engine.
  2. Disconnect the electrical connector of the rocker arm oil control solenoid.
  3. Connect a DMM to the control circuit of the rocker arm solenoid and ground.
  4. Turn ON the ignition, with the engine OFF.
Is the voltage near the specified value?		 12 V Go to Step 7  Go to Step 6 
6
  1. Inspect the solenoid control circuit of the rocker arm oil control solenoid for a short to ground.
  2. Repair as necessary. Refer to Wiring Repairs .
Was a repair necessary?		 - Go to Step 9  Go to Step 8 
7 Replace the rocker arm oil control solenoid. Refer to Rocker Arm Oil Control Solenoid Valve Replacement .
Is the action complete?		 - Go to Step 9  -
8 
  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 9  -
9
  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 10  Go to Step 2 
10 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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