Circuit Description
The camshaft position (CMP) sensor works in conjunction with a 1 X reluctor wheel on the camshaft. The powertrain control module (PCM) provides a 12-volt reference to the CMP sensor as well as a low reference and a signal circuit.
As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor. The sensors internal circuitry detects this and produces a signal which the PCM reads.
The CMP sensor 1 X signal is used by the PCM to determine if the cylinder at top dead center (TDC) is on the firing stroke or the exhaust stroke. The PCM can determine TDC for all cylinders by using the crankshaft position (CKP) sensor 24 X signal alone. The engine will start without a CMP signal as long as the PCM receives the CKP sensor 24 X signal. A slightly longer cranking time may be a symptom of this condition. The system attempts synchronization and looks for an increase in engine speed indicating that the engine started. If the PCM does not detect an increase in engine speed, the PCM assumes that the PCM incorrectly synchronized to the exhaust stroke and re-syncs to the opposite cam position. If the PCM detects that the CMP signal is constantly high, DTC P0343 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0343 Camshaft Position (CMP) Sensor Circuit High Voltage
Conditions for Running the DTC
| • | The engine is running. |
| • | The engine speed is less than 4,000 RPM. |
| • | DTC P0343 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
The PCM detects that the CMP sensor signal is high for more than 5 seconds.
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. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | ||||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||||||
2 |
Does the scan tool parameter increment? | -- | Go to Step 3 | Go to Step 4 | ||||||||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Testing for Intermittent Conditions and Poor Connections | ||||||||||
4 |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 5 | ||||||||||
Does the CMP sensor high to low and low to high transition counters increment when the test lamp contacts the signal circuit? | -- | Go to Step 6 | Go to Step 10 | |||||||||||
6 |
Is the voltage more than the specified value? | 0.2 V | Go to Step 8 | Go to Step 9 | ||||||||||
7 | Test the CMP sensor signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 10 | ||||||||||
8 | Test the low reference circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 10 | ||||||||||
9 | 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 . Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 11 | ||||||||||
10 | Test for an intermittent and for a poor connection at the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 14 | ||||||||||
11 |
Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 | ||||||||||
12 | Visually inspect the CMP sensor reluctor ring for the following conditions:
Refer to Camshaft and Bearings Cleaning and Inspection . Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13 | ||||||||||
13 | Replace the CMP sensor. Refer to Camshaft Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- | ||||||||||
14 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 15 | -- | ||||||||||
15 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 16 | ||||||||||
16 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||||
