DTC P0340 Camshaft Position (CMP) Sensor Circuit. Cadillac Catera 2000

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2000 🢒 Catera 🢒 Engine 🢒 Engine Controls - 3.0L (L81) 🢒 DTC P0340 Camshaft Position (CMP) Sensor Circuit

Handling ESD Sensitive Parts Notice
Engine Controls Components
Engine Data Sensors
OBD II Symbol Description Notice

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.

Conditions for Setting the DTC

The CMP signal is incorrect for at least 5 cycles.

Action Taken When the DTC Sets

•	The ECM illuminates the malfunction indicator lamp (MIL) and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.

•	The ECM will use a calculated spark retard value in order to minimize a knock during conditions when a knock is likely to occur. The calculated value will vary based on the engine speed and load.

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 .

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 MAF sensor, ECT sensor, and the 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.

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

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

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

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

Did you perform the Powertrain On-Board Diagnostic (OBD) System check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Review the Freeze Frame and/or failure records for this DTC and note the parameters.
Clear the DTCs.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the conditions for running the DTC as specified in the supporting text and as close to the freeze frame and/or failure records that were noted.
Check for any DTCs.

Does this DTC reset?

Go to Step 3

Go to Diagnostic Aids

Turn OFF the ignition.
Disconnect the CMP sensor connector.
Turn ON the ignition with the engine OFF.

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

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

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.

Turn OFF the ignition for 30 seconds.

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

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

Does the resistance measure less than the specified value?

5 ohms

Go to Step 5

Go to Step 11

Turn ON the ignition, with the engine OFF.
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

Turn OFF the ignition.
Connect the CMP sensor connector.
Disconnect the ECM.
Jumper the Engine Controls Power Relay control circuit to ground in order to supply power to the CMP sensor.
Connect the test light between the CMP sensor signal circuit at the ECM connector and B+.
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

Was the voltage more than the specified value?

5.2 V

Go to Step 10

Go to Step 8

Turn OFF the ignition.
Disconnect the ECM.
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.
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.
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

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

Is the action complete?

Go to Step 18

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

Is the action complete?

Go to Step 18

Disconnect the ECM.
Test the CMP sensor ground circuit for continuity between the CMP sensor connector and the ECM connector.
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

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

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

Is the action complete?

Go to Step 18

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

Is the resistance of the circuit less than the specified value?

5 ohms

Go to Step 16

Go to Step 15

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

Is the action complete?

Go to Step 18

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

Important: 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/Programming .

Is the action complete?

Go to Step 18

Use a scan tool in order to clear the DTCs.
Start the engine.
Allow the engine to idle until the engine reaches the normal operating temperature.
Select the DTC and the Specific DTC function.
Enter the DTC number that was set.
Operate the engine within the Conditions for Running this DTC until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate the diagnostic Passed?

Go to Step 19

Go to Step 2

Does the scan tool display any additional, undiagnosed DTCs?

Go to the applicable DTC table

System OK