GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2002 🢒 Corvette 🢒 Engine 🢒 Engine Controls - 5.7L 🢒 DTC P0343

Circuit Description

The camshaft position (CMP) sensor works in conjunction with a 1X reluctor wheel on the camshaft. The powertrain control module (PCM) provides a 12-volt reference, a low reference, and a signal circuit to the CMP sensor.

The CMP sensor determines whether a cylinder is on a firing stroke or on an exhaust stroke. A magnet within the sensor produces a magnetic field. The reluctor wheel of the rotating camshaft interrupts this magnetic field. The sensor's internal circuitry detects this field, and produces a signal which the PCM reads. The PCM uses this 1X signal in combination with the 24X signal of the crankshaft position (CKP) sensor. The PCM uses this information in order to determine the crankshaft position and the stroke. The PCM monitors for a loss of the CMP sensor signal.

As long as the PCM receives the CKP sensor 24X signal, the engine will start. The PCM can determine the top dead center for all of the cylinders just by using the CKP sensor 24X signal. The PCM uses the CMP sensor 1X signal in order to determine which stroke the cylinder at the top dead center is on. The PCM determines if the cylinder is on the firing stroke or on the exhaust stroke. The system attempts synchronization, and looks for an increase in the engine speed, indicating that the engine started. If the PCM does not detect an increase in the engine speed, the PCM assumes the PCM is incorrectly synchronized to the exhaust stroke. The PCM synchronizes to the opposite cam position. A slightly longer cranking time may be a symptom of this condition.

Conditions for Running the DTC

The engine speed is less than 4000 RPM.

Action Taken When the DTC Sets
    • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC
    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Diagnostic Aids
    • The following conditions may cause this DTC to set:
       - Camshaft reluctor wheel damage
       - A sensor that is in contact with the reluctor wheel
    • For an intermittent conditions, refer to Intermittent Conditions .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step verifies that the fault is present.

    2.

  2. If the duty cycle is present at the PCM connector, the 12-volt reference circuit, and the low reference circuit of the CMP sensor are OK.

    3.

  3. This step tests the 12-volt reference circuit of the CMP sensor.

    4.

  4. This step tests the low reference circuit of the CMP sensor .

    5.

  5. This step tests for a short to voltage on the CMP sensor signal circuit.

    6.

  6. This step tests for a short to ground on the CMP sensor signal circuit.

Step

Action

Value

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

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Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

  1. Connect a scan tool.
  2. Start the engine.
  3. Use the scan tool in order to monitor the CAM signal input High to Low transition.

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. In order to operate the vehicle under the conditions which set the DTC, use the following information:
    5. • The data in the Freeze Frame/Failure Records
    • The parameters listed in the Conditions for Running in the DTC

Does the DTC fail this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4

  1. Disconnect both PCM connectors. Refer to Powertrain Control Module Replacement .
  2. Locate the PCM connector C1 on the sensor side. Use a jumper wire in order to connect the low reference circuit of the CMP sensor to a known good ground.
  3. Locate the PCM connector C2 on the sensor side. Use a fused jumper wire in order to connect the 12-volt reference circuit of the CMP sensor to B+. Refer to Using Fused Jumper Wires in Wiring Systems.
  4. Probe the CMP sensor signal circuit with one lead of the DMM, and connect the other lead to a ground.
  5. Select the duty cycle option on the DMM.
  6. Crank the engine.

Is the duty cycle within the specified range?

45-55 %

Go to Step 17

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Connect the PCM connectors. Refer to Powertrain Control Module Replacement .
  3. Remove the intake manifold in order to access the CMP sensor. Refer to Intake Manifold Replacement in Engine Mechanical-5.7L.
  4. Disconnect the CMP sensor electrical connector.
  5. Turn ON the ignition, with the engine OFF.
  6. Use the DMM in order to measure the voltage from the 12-volt reference circuit of the CMP sensor to the battery ground.

Does the DMM display the specified voltage?

B+

Go to Step 6

Go to Step 8

6

Use a DMM in order to measure the voltage of the CMP sensor from the 12-volt reference circuit to the low reference circuit.

Does the DMM display the specified voltage?

B+

Go to Step 9

Go to Step 7

7

Test for an open in the low reference circuit of the CMP sensor. Refer to Testing for Continuity in Wiring Systems.

Did you find an open low reference circuit?

--

Go to Step 13

Go to Step 17

8

Test for an open or for a short to ground in the 12-volt reference circuit of the CMP sensor. Refer to Testing for Continuity in Wiring Systems.

Did you find the circuit open or shorted to a ground?

--

Go to Step 12

Go to Step 17

9

  1. Turn ON the ignition, with the engine OFF.
  2. Use a DMM in order to measure the voltage at the CMP sensor signal circuit to ground with the DMM.

Is the voltage less than the specified value?

1 V

Go to Step 10

Go to Step 14

10

Probe the CMP signal with a test lamp connected to battery voltage.

Does the test lamp illuminate?

--

Go to Step 15

Go to Step 11

11
  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C1. Refer to Powertrain Control Module Replacement .
  3. Use the DMM in order to test the continuity of the signal circuit from the sensor harness connector to the PCM . Refer to Testing for Continuity in Wiring Systems.

Is the resistance less than the specified value?

2 ohms

Go to Step 18

Go to Step 16

12

Repair the open, or repair the short to ground in the 12-volt reference circuit of the CMP sensor. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 20

--

13

Repair the open in the low reference circuit of the CMP sensor . Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 20

--

14

Repair the short to voltage in the CMP sensor signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 20

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15

Repair the short to ground in the CMP sensor signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 20

--

16

Repair the open in the CMP sensor signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 20

--

17
  1. Inspect for poor connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If you find a poor connection, repair the connection as necessary. Refer to Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 19

18

Replace the CMP sensor. Refer to Camshaft Position Sensor Replacement .

Did you complete the replacement?

--

Go to Step 20

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19

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 20

--

20
  1. Use a scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run, and pass?

--

Go to Step 21

Go to Step 2

21

With a scan tool, observe the stored information in Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK