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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1073 (Engine Controls Diagnosis - 6.6L (LLY) (DTC P0238 To DTC P0652)) >> Diagnosis >> DTC P0238 >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. 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. 4:  A short to voltage on the 5-volt reference circuit will cause DTC P0653 to set.
  2. 7:  This step tests the signal circuit of the boost pressure sensor for a short to voltage. The short may backfeed through the sensor to the 5-volt reference circuit causing DTC P0653 to set.
DTC P0238

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine Control Module (ECM) Connector End Views  or  Engine Controls Connector End Views 
1 Did you perform the Diagnostic System Check - Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls
2
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the Boost Pressure Sensor parameter with a scan tool.
Is the pressure more than the specified value?		 254 kPa (36 psi) Go to Step 4  Go to Step 3 
3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?		 - Go to Step 4  Go to Intermittent Conditions
4  Monitor the Diagnostic Trouble Code (DTC) Information with a scan tool.
Does the scan tool indicate that DTC P0653 is also set?		 - Go to Step 7  Go to Step 5 
5
  1. Turn OFF the ignition.
  2. Disconnect the electrical connector of the boost pressure. Refer to Boost Pressure Sensor Replacement .
  3. Turn ON the ignition, with the engine OFF.
Does the scan tool indicate that the Boost Pressure Sensor parameter is less than the specified value?		 36 kPa (5 psi) Go to Step 6  Go to Step 8 
6
  1. Remove the boost pressure sensor.
  2. Connect a jumper wire between each of the terminals in the boost pressure sensor harness connector and the corresponding terminal at the boost pressure sensor. Refer to Using Connector Test Adapters in Wiring Systems.
  3. Measure the voltage from the low reference circuit of the boost pressure sensor at the jumper wire terminal to a good ground with a DMM. Refer to Measuring Voltage Drop in Wiring Systems.
Is the voltage more than the specified value?		 0.2 V Go to Step 9  Go to Step 10 
7 
  1. Turn OFF the ignition.
  2. Disconnect the electrical connector of the boost pressure sensor. Refer to Boost Pressure Sensor Replacement .
  3. Turn ON the ignition, with the engine OFF.
Does the scan tool indicate that the Boost Pressure Sensor parameter is less than the specified value?		 36 kPa (5 psi) Go to DTC P0653 Go to Step 8 
8 Test the signal circuit of the boost pressure sensor for a short to voltage. Refer to Testing for a Short to Voltage andWiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 13 
9 Test the low reference circuit of the boost pressure sensor for high resistance or an open. Refer to Circuit Testing in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 11 
10 Inspect for poor connections at the boost pressure sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 12 
11 Inspect for poor connections at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 13 
12 Replace the boost pressure sensor. Refer to Boost Pressure Sensor Replacement .
Did you complete the replacement?		 - Go to Step 14  -
13 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 14  -
14
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?		 - Go to Step 2  Go to Step 15 
15 Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List System OK
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