GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 GMC C-Series Medium Duty Truck B7 🢒 Engine 🢒 Engine Controls - 6.5L (L65) 🢒 DTC P0238 Turbocharger Boost Sensor Circuit High Voltage

Object Number: 350888 Size: MF
Engine Controls Components
Cell 22: Engine Data Sensors
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The PCM operates a solenoid to control boost. This solenoid is normally open. By providing a ground path, the PCM energizes the solenoid which allows vacuum to pass to the wastegate valve. During normal operation, the PCM compares the wastegate duty cycle signal with the boost signal, and makes corrections to the duty cycle accordingly.

Conditions for Setting the DTC
    • The Boost Pressure is greater than or equal to 4.8 volts (202 kPa).
    • The engine speed is less than 3506 RPM.

Action Taken When the DTC Sets
    • The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive drive trip the diagnostic runs and fails.
    • The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the Failure Records store this information. If the diagnostic reports a failure on the second consecutive drive trip, the Freeze Frame records the operating conditions at the time of failure and updates the Failure Records.

Conditions for Clearing the MIL/DTC
    • The PCM will turn the MIL off after three consecutive trips without a fault condition.
    • A History DTC will clear after forty consecutive warm-up cycles during which the diagnostic does not fail (the coolant temperature has risen 5°C (40°F) from the start up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) of that same ignition cycle).
    • Use of a Scan Tool will clear the DTC codes.

Diagnostic Aids

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

An intermittent can be caused by the following:

    • Poor connections
    • A rubbed through wire insulation
    • A broken wire inside of the insulation

Test Description

The number(s) below refer to the step number(s) on the Diagnostic Table.

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

    2.

  2. If the scan tool 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 voltage is in the wiring.

Step

Action

Value(s)

Yes

No

1

Important: Before clearing any DTCs, use the scan tool Capture Info to save freeze frame and failure records for reference, as the scan tool loses data when using the Clear Info function.

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

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

Does the scan tool display a boost pressure greater than or equal to the specified value?

202 kPa

Go to Step 3

Go to Step 5

3

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

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 that the boost sensor is disconnected.
  2. Turn the ignition ON.
  3. Set the J 39200 digital multimeter to the mA scale.
  4. Measure the current across the boost sensor signal and the sensor ground circuit at the harness connector.

Is the current 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 Applicable DTC Table

Go to Diagnostic Aids

6
  1. Turn the ignition ON leaving the engine OFF.
  2. Connect the J 39200 digital multimeter to a ground.
  3. Probe the 5 volt reference circuit at the boost sensor harness.

Is the voltage greater than the specified value?

5.2 V

Go to Step 12

Go to Step 7

7
  1. Verify the boost sensor is disconnected.
  2. Using a J 39200 digital multimeter, measure the voltage across the boost sensor 5 volt reference circuit to the sensor ground at the harness connector.

Is the voltage 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.
  2. If a problem is found repair as necessary.

Is the action complete?

4.8-5.2 V

Go to Step 15

Go to Step 9

9

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

Is the action complete?

--

Go to Step 15

Go to Step 9

10

Replace the boost sensor. Refer to Boost Sensor Replacement .

Is the action complete?

--

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.

Is the action complete?

--

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

Is the action complete?

--

Go to Step 15

Go to Step 14

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

Is the action complete?

--

Go to Step 15

Go to Step 14

14

Important: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM.

Is the action complete?

--

Go to Step 15

--

15
  1. Using the scan tool, clear the DTCs.
  2. Start engine and idle at normal operating temperature.
  3. Select DTC, Specific, then enter the DTC number which was set.
  4. Operate the vehicle, within the Conditions for Setting this DTC, until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate the diagnostic Passed?

--

Go to Step 15

Go to Step 2

16

Does the scan tool display any additional undiagnosed DTCs?

--

Go to the Applicable DTC Table

System OK