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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 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. 16:  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 camshaft position (CMP) sensor. Refer to Camshaft Position (CMP) Sensor Replacement .
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the 5-volt reference circuit of the CMP sensor to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
Does the DMM display a reading within the specified range?		 4.8-5.2 V Go to Step 5  Go to Step 4 
4 Does the DMM display a reading above the specified value? 5.2 V Go to Step 9  Go to Step 8 
5
  1. Turn OFF the ignition.
  2. Disconnect the engine control module (ECM).
  3. Measure the resistance of the 5-volt reference circuit of the CMP sensor with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the resistance above the specified value?		 5 ohm Go to Step 10  Go to Step 6 
6
  1. Connect the ECM.
  2. Connect a jumper wire between each of the terminals in the CMP sensor harness connector and the corresponding terminals at the CMP sensor. Refer to Using Connector Test Adapters in Wiring Systems.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the low reference circuit of the CMP 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 11  Go to Step 7 
7
  1. Turn OFF the ignition.
  2. Remove the jumper wires from the CMP sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the Cam Signal Present parameter with a scan tool.
  5. Momentarily and repeatedly probe the signal circuit of the CMP sensor with a test lamp that is connected to battery voltage.
Does the Cam Signal Present parameter change when the test lamp contracts the signal circuit?		 - Go to Step 12  Go to Step 13 
8 Test the CMP sensor 5-volt reference circuit for an open 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 18  Go to Step 15 
9 Test the CMP sensor 5-volt reference circuit for a short to voltage. Refer toCircuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 18  Go to Step 15 
10 Repair the high resistance in the CMP sensor 5-volt reference circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 18  -
11 Test the CMP sensor low reference circuit for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 18  Go to Step 15 
12 Test the CMP sensor signal circuit for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 18  Go to Step 14 
13 Test the CMP sensor signal for the following conditions:
Did you find and correct the condition?		 - Go to Step 18  Go to Step 15 
14 Inspect 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 18  Go to Step 16 
15 Inspect 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 18  Go to Step 17 
16 
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 18  -
17 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 18  -
18
  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 19 
19 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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