Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provide an overview of each diagnostic category. |
DTC Descriptors
DTC P0340: Camshaft Position (CMP) Sensor CircuitDTC P0341: Camshaft Position (CMP) Sensor Performance
Diagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
CMP 5-Volt Reference | P0642 | P0340 | P0340 | P0340 | -- |
CMP Sensor Signal | P0340 | P0340 | P0340 | P0340 | -- |
CMP Low Reference | -- | P0340, P0237 | P0340 | -- | -- |
Typical Scan Tool Data
Circuit | Normal Range | Short to Ground | Open | Short to Voltage |
|---|---|---|---|---|
Operating Conditions: Engine running | ||||
CMP 5-Volt Reference Voltage | Yes | No | No | Yes |
CMP Sensor Signal | Yes | No | No | No |
CMP Low Reference | Yes | -- | No | -- |
Circuit/System Description
The hall effect camshaft position (CMP) sensor produces 3 ON/OFF pulses for each revolution of the camshaft. The CMP output is pulse width encoded. The engine control module (ECM) uses the CMP and crankshaft position (CKP) output pulses to determine the engine speed and position. The CMP is connected directly to the ECM by the following circuits:
| • | The 5-volt reference circuit |
| • | The low reference circuit |
| • | The CMP sensor signal circuit |
Conditions for Running the DTC
P0340
| • | DTC P0642 and P0643 are not set. |
| • | Battery voltage is between 10-16 V. |
P0341
| • | DTC P0340, P0642, and P0643 are not set. |
| • | Battery voltage is between 10-16 V. |
| • | Engine speed is more than 350 RPM. |
| • | Cam signal inputs are recognized. |
Conditions for Setting the DTC
P0340
Number of cam signal inputs during 1 revolution is less than 1.
P0341
The ECM detects extra or missing CAM signal inputs.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/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
| • | An intermittent CMP sensor signal may cause DTC P0340 or P0341 to set. Wiggle the wiring harness with the engine running and observe the Cam Signal Missed parameter of the scan tool. If the parameter indicates anything other than 0, there is an intermittent condition. |
| • | If the CMP sensor signal is lost while running, the engine will operate normally. If the CMP sensor signal is not present on start-up, the engine will not start. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
If DTCs P0642 or P0643 are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
Circuit/System Testing
- With the key ON and the CMP sensor disconnected, measure the voltage between the 5-volt reference and a good ground and observe that the DMM measures 4.5-5.5 volts.
- With the key ON and the CMP sensor disconnected, measure the voltage between the 5-volt reference circuit and the low reference circuit and observe that the DMM measures 4.5-5.5 volts.
- With the key ON and the CMP sensor disconnected, connect a fused jumper wire to the signal circuit and momentarily and repeatedly probe the low reference circuit, and observe if the Cam Signal Present and Engine RPM parameters change.
- Ensure that the CMP sensor circuits are not routed too closely to the fuel injector wiring, after-market add-on electrical equipment, solenoids, relays, or motors.
- Inspect the CMP sensor for physical damage, loose or improper installation, excessive air gap, or foreign material passing between the sensor and the reluctor wheel.
- Inspect the CMP reluctor wheel for physical damage, improper installation, or excessive endplay or looseness.
- If no other condition is found, replace the CMP sensor.
| ⇒ | If the DMM does not measure 4.5-5.5 volts, test the 5-volt reference for an open or high resistance. If the circuits test normal, replace the ECM. |
| ⇒ | If the DMM does not measure 4.5-5.5 volts, test the low reference for an open or high resistance. If the circuits test normal, replace the ECM. |
| ⇒ | If the cam signal and engine RPM parameters do not change, test the signal circuit for an open, high resistance, a short to ground, a short to voltage. If the circuits test normal, replace the ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
