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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1070 (Engine Controls Diagnosis - 6.6L (Lb7) (DTCS P0237 To P0611)) >> Diagnosis >> DTC P0340 >> 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. 2:  If the engine starts and runs, the condition is suspected to be intermittent. If there is a condition with the CMP sensor circuit the vehicle will not run.
  2. 6:  This step determines if the CMP sensor is working correctly.
  3. 13:  Inspect the CMP sensor for physical damage. The camshaft may damage the sensor.
DTC P0340

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  Attempt to start the engine.
Does the engine start and run?		 - Go to Diagnostic Aids Go to Step 3 
3
  1. Turn OFF the ignition.
  2. Disconnect the CMP sensor. Refer to Camshaft Position (CMP) Sensor Replacement .
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the 12-volt reference circuit to the low reference circuit of the CMP sensor with a DMM. Refer to Circuit Testing in Wiring Systems.
Does the DMM display a reading above the specified value?		 10 V Go to Step 5  Go to Step 4 
4 Measure the voltage from the 12-volt reference circuit and to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the voltage above the specified value?		 10 V Go to Step 7  Go to Step 8 
5 Measure the voltage from the CMP sensor signal circuit and to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the voltage at the specified value?		 0 V Go to Step 6  Go to Step 9 
6 
  1. Turn OFF the ignition.
  2. Reconnect the CMP sensor.
  3. Disconnect the ECM connector C1.
  4. Carefully remove the CMP signal circuit pin from the ECM connector. Refer to Push to Seat Connectors in Wiring Systems.
  5. Reconnect the ECM connector.
  6. Connect a DMM between the CMP signal circuit pin at the ECM and a good ground.
  7. Crank the engine and measure the DC duty cycle of the CMP signal circuit with a DMM.
Is the DC duty cycle within the specified range?		 45-55% Go to Step 12  Go to Step 10 
7 Test the low reference circuit for an open. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 15  Go to Step 12 
8 Test the 12-volt reference circuit for an open or a short to ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 15  Go to Step 12 
9 Test the CMP signal circuit for a short to voltage or a short to the 12-volt reference circuit. Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 15  Go to Step 14 
10 Test the CMP signal circuit for an open or a short to ground. Refer to Testing for Continuity , Testing for Short to Ground , and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 15  Go to Step 11 
11 Check for poor connections at the CMP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 15  Go to Step 13 
12 Check for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 15  Go to Step 14 
13 
IMPORTANT: Inspect the CMP sensor for physical damage before replacing.
Replace the CMP sensor. Refer to Camshaft Position (CMP) Sensor Replacement .Did you complete the replacement?		 - Go to Step 15  -
14 Replace the ECM. Refer to Engine Control Module (ECM) 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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