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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Chevy C Cab/Chassis HD (GMT 400) 🢒 Engine 🢒 Engine Controls - 6.5L (L65) 🢒 DTC P0238

Circuit Description

The powertrain control module (PCM) controls boost using the turbocharger wastegate solenoid. The solenoid is pulse width modulated (PWM). When the wastegate solenoid is not energized, the vacuum to the turbocharger wastegate solenoid is vented to atmosphere through the solenoid. As the pulse width is increased by the PCM, more vacuum is applied through the solenoid to the wastegate actuator. At idle a higher vacuum to the wastegate actuator helps keep the wastegate closed. At higher engine speeds the vacuum supplied by the solenoid is less, allowing the turbocharger boost pressure to overcome the wastegate actuator.

Conditions for Running the DTC
    • The PCM performs this diagnostic trouble code (DTC) diagnostic continuously.
    • The engine speed less than 3,506 RPM.

Conditions for Setting the DTC
    • The boost pressure is more than or equal to (202 kPa).
    • All diagnostic set conditions were met for 2 seconds.

Action Taken When the DTC Sets
    • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC
    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

Very little boost can be attained by revving the engine in neutral.

An intermittent may be caused by the following conditions:

    • Poor connections
    • Rubbed through wire insulation
    • Broken wire inside the insulation

Test Description

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

  1. This step will determine if the PCM is responding to a low signal voltage. This will indicate that the PCM is OK.

    2.

  2. If the scan display is still less than or equal to 9 kPa by disconnecting the PCM, the short to voltage is in the wiring.

    3.

  3. If the voltmeter value stays the same by disconnecting the PCM, the short to battery voltage is in the wiring.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2
  1. Connect a scan tool.
  2. Start the engine and let the engine idle.

Does the scan tool display a Boost Pressure more than or equal to the specified value?

202 kPa

Go to Step 3

Go to Step 5

3

  1. Turn OFF the ignition.
  2. Disconnect the boost sensor electrical connector.
  3. Using a fused jumper, jumper the boost sensor signal to the sensor low reference.
  4. Turn ON the ignition.

Does the scan tool display a Boost Pressure less than or equal to the specified value?

10 kPa

Go to Step 6

Go to Step 4

4
  1. Verify the boost sensor is disconnected.
  2. Turn ON the ignition.
  3. Set the DMM to the mA scale.
  4. Measure the current across the boost sensor signal and the sensor low reference circuit at the harness connector.

Does the current measure less than the specified value?

10 mA

Go to Step 6

Go to Step 11

5
  1. The DTC is intermittent.
  2. If no additional DTCs are stored, refer to Diagnostic Aids.
  3. If additional DTCs are stored, refer to those tables first.

Are any additional DTCs stored?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Diagnostic Aids

6
  1. Turn ON the ignition, with the engine OFF.
  2. Connect the DMM to a ground.

    3. Probe the 5-volt reference circuit at the boost sensor harness.

Does the voltage measure more than the specified value?

5.2 V

Go to Step 12

Go to Step 7

7
  1. Verify that the boost sensor is disconnected.
  2. Using a DMM, measure the voltage across the boost sensor 5-volt reference circuit to the sensor low reference at the harness connector.

Does the voltage measure within the specified range?

4.8-5.2 V

Go to Step 8

Go to Step 13

8
  1. Check for an open or a proper sensor signal terminal connection at the PCM and the boost sensor.
  2. If a problem is found, repair as necessary.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 9

9

  1. Check the boost sensor port for a restriction.
  2. If a problem is found, repair as necessary.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 10

10

  1. Replace the boost sensor.
  2. Refer to Boost Sensor Replacement .

Did you complete the replacement?

--

Go to Step 15

--

11
  1. Check for a short to voltage in the boost sensor signal circuit.
  2. If a problem is found, repair as necessary.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

12
  1. Check for a short to battery voltage in the boost sensor 5-volt reference circuit.
  2. If a problem is found, repair as necessary.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

13
  1. Check for an open or a proper sensor ground terminal connection at the PCM and the boost sensor.
  2. If a problem is found, repair as necessary.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

14

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 15

--

15
  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 16

Go to Step 2

16

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

System OK