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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2001 🢒 Catera 🢒 Engine 🢒 Engine Controls - 3.0L (L81) 🢒 DTC P0340

Circuit Description

The camshaft position (CMP) sensor works in conjunction with a single tooth reluctor wheel on the bank 2 intake camshaft. The engine control module (ECM) pulls up the CMP sensor signal circuit to 5 volts and monitors this voltage. As the reluctor wheel tooth rotates past the sensor, the sensors internal circuitry pulls the signal circuit to ground, creating a square wave signal that is used by the ECM. The reluctor wheel tooth covers 180 degrees of the camshaft circumference. This causes the CMP signal voltage to transition once per crankshaft revolution. This signal, when combined with the crankshaft position (CKP) sensor signal, enables the ECM to determine exactly which cylinder is on a firing stroke. The ECM can then properly synchronize the ignition system, the fuel injectors, and the knock control. Note: that as long as the CKP signal is available, the engine can start and run, even if there is no CMP sensor signal the ECM will default to a non-sequential fuel injector operation.

Conditions for Running the DTC

The engine speed is more than 20 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 ECM turns OFF the MIL after 3 consecutive drive trips that the diagnostic runs and passes.
    • A history DTC clears after forty consecutive warm-up cycles in which no failures are reported by this diagnostic or any other emissions related diagnostic.
    • The scan tool clears the MIL/DTC.

Diagnostic Aids

Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector. Using this kit prevents damage to the harness or component terminals. Refer to Using Connector Test Adapters in Wiring Systems. For an intermittent, refer to Symptoms - Engine Controls .

Check for the following conditions:

    • Poor connections at the ECM or at the component--Inspect the harness connectors for any backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
    • Damaged harness--Inspect the wiring harness for any damage. If the harness appears to be OK, monitor the resistance of the circuit while moving the harness in different locations. A fluctuation in the resistance will indicate the area of a possible concern.
    •  Check the sensor for a proper installation. A sensor that is loose or not fully seated, causing an excessive air gap between the sensor and the reluctor wheel, may cause this DTC to set.

       Important: The CMP sensor ground is shared with the mass air flow (MAF) sensor, engine coolant temperature (ECT) sensor, and the throttle position (TP) sensor. Do not use a test lamp to test the continuity of this circuit back through the ECM. Damage to the ECM will result.

    • If other DTCs are set that share the same ground circuit, test the point where the circuits splice, and where the circuit connects to the ECM for opens or high resistance.

If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.

Test Description

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

  1. This step tests for proper switched B+ voltage to the sensor.

    2.

  2. This step tests the integrity of the CMP sensor ground circuit through the ECM to battery ground.

    3.

  3. This step tests for the proper ECM pull-up voltage to the sensor.

    4.

  4. This step verifies that the CMP sensor can produce a signal to the ECM.

DTC P0340 - Camshaft Position (CMP) Sensor Circuit

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2
  1. Review the Freeze Frame/Failure Records for this DTC and note the parameters.
  2. Clear the DTCs.
  3. Turn OFF the ignition for 30 seconds.
  4. Start the engine.
  5. Operate the vehicle within the Conditions For Running the DTC, and as close to the data observed in the Freeze Frame/Failure Records.
  6. Check for any DTCs.

Did the DTC fail this ignition?

--

Go to Step 3

Go to Diagnostic Aids

3

  1. Turn OFF the ignition.
  2. Disconnect the CMP sensor connector.
  3. Turn ON the ignition, with the engine OFF.

    4. Important: Do not use the CMP sensor ground circuit for the following test. Internal ECM damage will result.

  4. Probe the CMP sensor switch battery positive circuit in the harness connector (ECM side) with the test lamp connected to a known good ground.

Does the test light illuminate?

--

Go to Step 4

Go to Step 9

4

Important: Make sure the ECM has shut down prior to measuring the sensor ground circuit resistance. This can be verified by loss of communication on the scan tool.

  1. Turn OFF the ignition for 30 seconds.

    2. Important: Do not use a test lamp to test the continuity of the sensor ground circuit. Damage to the ECM will result.

  2. Using a DMM measure the resistance of the CMP sensor ground circuit from the sensor connector to battery ground.

Is the resistance less than the specified value?

5 ohms

Go to Step 5

Go to Step 11

5

  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage from the CMP sensor signal circuit to the CMP sensor ground circuit using the DMM.

Is the voltage within the specified range?

4.8-5.2 V

Go to Step 6

Go to Step 7

6

  1. Turn OFF the ignition.
  2. Connect the CMP sensor connector.
  3. Disconnect the ECM.
  4. Jumper the engine controls power relay control circuit to ground in order to supply power to the CMP sensor.
  5. Connect the test light between the CMP sensor signal circuit at the ECM connector and B+.
  6. Observe the test light while cranking the engine. The engine will not start.

Does the test light blink while the engine is cranking?

--

Go to Step 16

Go to Step 12

7

Is the voltage more than the specified value?

5.2 V

Go to Step 10

Go to Step 8

8
  1. Turn OFF the ignition.
  2. Disconnect the ECM.
  3. Test the harness for continuity of the CMP sensor signal circuit with the DMM between the CMP sensor connector and the ECM connector. The DMM should indicate very low resistance.
  4. Test the harness for continuity of the CMP sensor signal circuit with the DMM between the CMP sensor connector and ground. The DMM should indicate OL.
  5. Repair the wiring as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 16

9

Repair the switched B+ circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 18

--

10

Repair the signal circuit shorted to B+. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 18

--

11
  1. Disconnect the ECM.
  2. Test the CMP sensor ground circuit for continuity between the CMP sensor connector and the ECM connector.
  3. Repair the open/high resistance in the CMP sensor ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 14

12

Test the CMP sensor for the following conditions:

    • Poor connections or poor terminal tension at the CMP sensor harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
    • The sensor for proper installation. A sensor that is loose or not fully seated could cause an excessive air gap between the sensor and the reluctor wheel.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 13

13

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

Did you complete the replacement?

--

Go to Step 18

--

14

Measure the resistance from the ground stud at the ECM to battery ground.

Is the resistance less than the specified value?

5 ohms

Go to Step 16

Go to Step 15

15

Repair the open or high resistance in the reference ground circuit to the ECM. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 18

--

16

Test for a poor connections or poor terminal tension at the ECM harness connector. 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 18

Go to Step 17

17

Important: 

   • Perform the idle learn procedure when replacing the ECM or the throttle body.
   • This vehicle is equipped with a theft deterrent system which interfaces with the engine control module (ECM). Program the new ECM with the frequency code of the theft deterrent module that is currently on the vehicle.

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the action?

--

Go to Step 18

--

18
  1. Use the 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 19

Go to Step 2

19

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

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

--

Go to Diagnostic Trouble Code (DTC) List

System OK