P0340
DTC P0340
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC P0340
- Camshaft Position Sensor Circuit
Diagnostic Fault Information
Circuit/System Description
The 4X camshaft position sensor circuits consist of an engine control module (ECM) supplied 5 V reference circuit, low reference circuit, and an output signal circuit. The camshaft position sensor is an internally magnetic biased digital output integrated circuit sensing device. The sensor detects magnetic flux changes between the peaks and valleys of a 4-tooth reluctor wheel attached to the camshaft. As each reluctor wheel tooth rotates past the camshaft position sensor, the resulting change in the magnetic field is used by the sensor electronics to produce a digital output pulse. The sensor returns a digital ON/OFF DC voltage pulse of varying frequency, with 2 narrow, and 2 wide output pulses per camshaft revolution that represent an image of the camshaft reluctor wheel. The frequency of the camshaft position sensor output depends on the velocity of the camshaft. The ECM decodes the narrow and wide tooth pattern to identify camshaft position. This information is then used to sequence the ignition timing and fuel injection events for the engine. The ECM also uses camshaft position sensor output information to determine the camshaft relative position to the crankshaft, to control the camshaft position actuator if equipped, and for limp-home operation.
Conditions for Running the DTC
* The mass air flow (MAF) is greater than 3 grams per second.
* DTC P0101, P0102, P0103, P0641, or P0651 is not set.
* The engine is cranking or running.
* DTC P0340 runs continuously when the above conditions are met.
Conditions for Setting the DTC
Note: The ECM detects engine movement by sensing the airflow through the MAF sensor, when airflow is greater than 3 grams per second, or by sensing crankshaft position sensor pulses.
* The ECM detects that the starter is commanded on and the engine has been cranking for more than 4 s without a camshaft position sensor pulse.
* The ECM detects that the engine has started, but did not receive a camshaft position sensor pulse during the first engine revolution.
* The ECM detects that the engine is running, but does not receive a camshaft position sensor pulse for 800 of 1000 engine cycles.
Action Taken When the DTC Sets
* DTC P0340 is a Type B DTC.
* The camshaft position actuator if equipped is commanded to the parked position.
* The ignition system defaults to a failed camshaft position sensor limp home mode.
Conditions for Clearing the DTC
DTC P0340 is a Type B DTC.
Diagnostic Aids
* With a DTC set, the engine may crank for an extended period of time during start-up.
* This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to Battery Inspection/Test (Battery Inspection/Test).
Reference Information
Schematic Reference
Engine Controls Schematics (LS3) ([1][2]Electrical Diagrams) Engine Controls Schematics (LS7) ([1][2]Electrical Diagrams) Engine Controls Schematics (LS9) ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Electronic Ignition System Description (Electronic Ignition System Description)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing For Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Special Tools
J 35616-A/BT-8637 Connector Test Adapter Kit
Circuit/System Verification
1. Engine idling, observe the scan tool Camshaft Position Active Counter parameter. The parameter should be incrementing.
2. Engine idling, observe the DTC information with a scan tool. DTC P0340 should not set.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the B23 camshaft position sensor.
2. Ignition OFF and all vehicle systems OFF, it may take 2 minutes for all vehicle systems to power down, test for less than 1 ohm on the camshaft position low reference circuit, terminal B, and ground.
• If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.
3. Ignition ON, test for 4.8-5.2 V between the camshaft position 5 V reference circuit terminal A and ground.
• If less than the specified range, test the 5 V reference circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the K20 ECM.
• If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
4. Ignition ON, test for 4.8-5.2 V between the camshaft position signal circuit terminal C and ground.
• If less than the specified range, test the signal circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the K20 ECM.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
5. Ignition OFF, connect a fused jumper wire to the camshaft position signal circuit terminal C.
6. Ignition ON, momentarily touch the other the other end of the fused jumper wire to the battery negative post. The scan tool should show the Camshaft Position Active counter incrementing.
• If the Camshaft Position Active counter increments, test or replace the B23 camshaft position sensor.
• If the Camshaft Position Active counter does not increment, replace the K20 ECM.
Component Testing
Note: You must perform the Circuit/System Testing before proceeding with Component Testing.
1. Inspect the camshaft position sensor for correct installation. Remove the camshaft position sensor from the engine and inspect the sensor O-ring for damage.
• If the sensor is loose, incorrectly installed, or damaged, replace the B23 camshaft position sensor.
2. Connect the camshaft position sensor harness connector to the B23 camshaft position sensor.
3. Ignition ON, engine OFF. Observe the Camshaft Position Active counter parameter on the scan tool.
4. Pass a flat steel object across the tip of the sensor repeatedly. The Camshaft Position Active counter parameter should increment with each pass of the steel object.
• If the parameter does not increment, replace the B23 camshaft position sensor.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Camshaft Position Sensor Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming