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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1472 (Engine Control System - Diagnosis - 4.2L (DTC P0140 To DTC P0506)) >> Diagnosis >> DTC P0340 >> Test Description

Test Description

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The number below refers to the step number on the diagnostic table.

  1. 6:  This step tests the output of the CMP sensor. If the duty cycle is not within the specified range the sensor is bad.
DTC P0340

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Powertrain Control Module (PCM) 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. Start the engine.
  2. Observe the CMP Active Counter parameter with a scan tool.
Does the scan tool parameter increment?		 - Go to Step 3  Go to Step 4 
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 Diagnostic Aids
4
  1. Turn OFF the ignition.
  2. Disconnect the CMP sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the 12-volt reference circuit to a good ground with a DMM. Refer to Probing Electrical Connectors in Wiring Systems.
Is the voltage more than the specified value?		 10 V Go to Step 5  Go to Step 7 
5
  1. Turn OFF the ignition.
  2. Jumper the CMP circuits from the CMP sensor to the CMP sensor harness connector. Refer to Using Connector Test Adapters in Wiring Systems.
  3. Turn ON the ignition with the engine OFF.
  4. Measure the Voltage Drop from the low reference circuit of the CMP sensor to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the voltage more than the specified value?		 0.2 V Go to Step 8  Go to Step 6 
6 
  1. Leave the jumper wires installed.
  2. Remove the jumper wire from the CMP signal circuit on the PCM side.
  3. Start the engine.
  4. Measure the duty cycle from the CMP signal circuit on the sensor side and to a good ground with a DMM.
Is the duty cycle within the specified range?		 40-50% Go to Step 9  Go to Step 10 
7 Test the 12-volt reference circuit for an open, high resistance or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 15  Go to Step 11 
8 Test the low reference circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 15  Go to Step 11 
9 Test the signal circuit for an open, short to ground or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 15  Go to Step 11 
10 Test for an intermittent and for a poor connection at the CMP 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 15  Go to Step 12 
11 Test for an intermittent and for a poor connection at the PCM. 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 15  Go to Step 14 
12
  1. Remove the CMP sensor.
  2. Visually inspect the CMP sensor for the following conditions:
    • Physical damage
    • Loose or improper installation
Did you find and correct the condition?		 - Go to Step 15  Go to Step 13 
13 Replace the CMP sensor. Refer to Camshaft Position (CMP) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 15  -
14 Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?		 - Go to Step 15  -
15
  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 16 
16 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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