GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 2003 🢒 Aurora 🢒 Engine 🢒 Engine Controls - 4.0L 🢒 DTC P0340

Circuit Description

The powertrain control module (PCM) uses the camshaft position (CMP) sensor high resolution signal in order to determine the position of the valve train in relation to the engine cylinders. The PCM uses the CMP high resolution signal in order to sequence the ignition system and the fuel injectors.

The PCM supplies a 12-volt reference and a low reference to the CMP sensor. The CMP sensor returns a signal pulse in response to the reluctor track, located on the camshaft sprocket. If during operation, the PCM detects a loss of CMP sensor high resolution signal, DTC P0340 will set.

Conditions for Running the DTC

No CKP sensor DTCs set with the engine running more than 400 RPM.

Conditions for Setting the DTC

The PCM detects a loss of CMP sensor high resolution signal.

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:
       - Damage to the camshaft sprocket
       - Incorrect sensor installation
       - The sensor coming in contact with the camshaft sprocket
       - Excessive air gap between the camshaft sprocket and the sensor
       - A cracked or damaged sensor
       - Foreign material passing between the sensor and the sprocket
    • If the condition is intermittent, refer to Engine Controls Schematics .

Test Description

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

  1. This step determines if the 12-volt reference circuit to the CKP A, the CKP B, and the CMP is shorted to a ground. If all 3 DTCs are set, this indicates the circuit is shorted to a ground or a sensor is internally shorted. All 3 DTCs set because the 12-volt reference circuit is internally connected within the PCM. The engine will not start with this condition.

    2.

  2. This step determines if the CMP sensor is shorted internally. If the 12-volt reference parameter changes from Fault to OK, the condition is with the sensor.

    3.

  3. This step determines if the CKP A sensor is shorted internally. If the 12-volt reference parameter changes from Fault to OK, the condition is with the sensor.

    4.

  4. This step determines if the CKP B sensor is shorted internally. If the 12-volt reference parameter changes from Fault to OK, the condition is with the sensor.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain Control Module 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. Connect a scan tool.
  2. Attempt to start the engine.
  3. Observe the DTC information with a scan tool.

Are DTCs P0335, P0340, and P0385 set?

--

Go to Step 8

Go to Step 3

3
  1. Start the engine.
  2. Observe the CMP sensor RPM parameter with a scan tool.

Does the scan tool parameter indicate RPM?

--

Go to Step 4

Go to Step 5

4

  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 5

Go to Diagnostic Aids

5

  1. Turn OFF the ignition.
  2. Disconnect the CMP sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the 12-volt reference circuit of the CMP sensor with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 6

Go to Step 12

6
  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 13

Go to Step 7

7
  1. Turn OFF the ignition.
  2. Remove the jumpers from the CMP circuits.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the CMP sensor RPM 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 CMP sensor RPM change when the test lamp contacts the signal circuit?

--

Go to Step 15

Go to Step 14

8

  1. Disconnect the CMP sensor.
  2. Observe the 12-volt reference parameter with a scan tool.

Does the 12-volt reference display OK?

--

Go to Step 17

Go to Step 9

9

  1. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Disconnect the CKP A sensor.
  3. Observe the 12-volt reference parameter with a scan tool.

Does the 12-volt reference display OK?

--

Go to Step 18

Go to Step 10

10

  1. Disconnect the CKP B sensor.
  2. Observe the 12-volt reference parameter with a scan tool.

Does the 12-volt reference display OK?

--

Go to Step 19

Go to Step 11

11

Test the 12-volt reference circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 16

12

Test the 12-volt reference circuit for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 16

13

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 21

Go to Step 16

14

Test the high resolution signal circuit for a 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 21

Go to Step 16

15

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 21

Go to Step 17

16

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 21

Go to Step 20

17

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

Did you complete the replacement?

--

Go to Step 21

--

18

Replace the CKP A sensor. Refer to Crankshaft Position Sensor Replacement .

Did you complete the replacement?

--

Go to Step 21

--

19

Replace the CKP B sensor. Refer to Crankshaft Position Sensor Replacement .

Did you complete the replacement?

--

Go to Step 21

--

20

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 21

--

21

  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 22

22

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