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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2004 🢒 CTS 🢒 DTC 🢒 DTC P0343

Circuit Description

The camshaft position (CMP) sensor works in conjunction with a 1X 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 1X 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 CKP sensor signal alone. The engine will start without a CMP signal as long as the PCM receives the CKP sensor 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.

Conditions for Running the DTC
    • The engine is running.
    • The engine speed is less than 4,000 RPM.

Conditions for Setting the DTC

The PCM detects that the CMP sensor signal is high for 1.5 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.

Diagnostic Aids
    • The following conditions may cause this DTC to set:
       - Camshaft reluctor ring damage
       - The sensor coming in contact with the reluctor ring
       - Foreign material passing between the sensor and the reluctor ring
       - Excessive camshaft end-play
       - Wiring routed too close to secondary ignition components
    • If the condition is intermittent, refer to Intermittent Conditions .

Test Description

The number below refers to the step number on the diagnostic table.

  1. This step tests the CMP sensor and circuits from the CMP sensor to the PCM. If there is not duty cycle displayed or if the duty cycle is not within range there is a problem with the sensor or the circuits.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2
  1. Start the engine.
  2. Observe the camshaft position (CMP) sensor high to low and low to high transition parameter with a scan tool.

Does the scan tool parameter increment?

--

Go to Step 3

Go to Step 4

3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4

  1. Disconnect the powertrain control module (PCM). Refer to Powertrain Control Module Replacement .
  2. Jumper the low reference circuit of the CMP sensor from the PCM connector to a good ground. Refer to Using Connector Test Adapters in Wiring Systems.
  3. Jumper the 12-volt reference circuit of the CMP sensor from the PCM connector to battery voltage. Refer to Using Connector Test Adapters in Wiring Systems.
  4. Measure the DC duty cycle on the signal circuit of the CMP sensor at the PCM connector with a DMM while cranking the engine.

Is the duty cycle within the specified range?

45-50%

Go to Step 10

Go to Step 5

5
  1. Turn OFF the ignition.
  2. Connect the PCM. Refer to Powertrain Control Module Replacement .
  3. Remove fuel pump relay using a J 43244 .
  4. Remove the intake manifold. Refer to Intake Manifold Replacement in Engine Mechanical.
  5. Disconnect the CMP sensor.
  6. Turn ON the ignition, with the engine OFF.
  7. Probe the signal circuit of the CMP sensor with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 7

Go to Step 6

6
  1. Turn OFF the ignition.
  2. Jumper the CMP circuits from the CMP sensor to the CMP sensor harness connector. Refer to Using Connector Test Adapters in Wiring Systems.
  3. Turn ON the ignition with the engine OFF.
  4. Measure the Voltage Drop from the low reference circuit of the CMP sensor to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.

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 in Wiring Systems.

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 in Wiring Systems.

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 in Wiring Systems.

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 PCM. 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 15

Go to Step 14

11
  1. Remove the CMP sensor. Refer to Camshaft Position Sensor Replacement .
  2. Visually inspect the CMP sensor for the following conditions:
    3. • Physical damage
    • Loose or improper installation

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

12
  1. Visually inspect the CMP sensor reluctor ring for damage.
  2. If the CMP reluctor ring is damaged, refer to Camshaft and Bearings Cleaning and Inspection in Engine Mechanical.

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 Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 15

--

15
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

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?

--

Go to Diagnostic Trouble Code (DTC) List

System OK