GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The camshaft position (CMP) sensor correlates the crankshaft to camshaft position so that the engine control module (ECM) can determine which cylinder is ready to be fueled by the injector. As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor and sends a signal to the ECM through the signal circuit. The CMP sensor also determines which cylinder is misfiring. The CMP sensor circuits consists of the following:

    • An ignition 1 voltage
    • A low reference
    • A CMP signal

If the ECM detects no pulses from the CMP sensor, this DTC sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0342 Camshaft Position (CMP) Sensor.

Conditions for Running the DTC

    • DTCs P0335, P0336, P0337, P1320, and P1321 are not set.
    • The engine is running.
    • DTC P0342 runs continuously when the above condition is met.

Conditions for Setting the DTC

The ECM detects no CMP signal for more than 1 second.

Action Taken When the DTC Sets

    • The malfunction indicator lamp (MIL) will illuminate after 3 consecutive trips with a fail.
    • The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.
    • A history DTC is stored.

Conditions for Clearing the MIL/DTC

    • The MIL will turn OFF after 4 consecutive ignition cycles in which the diagnostic runs without a fault.
    • DTCs can be cleared by using the scan tool.
    • Disconnect the ECM battery feed for more than 10 seconds.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine 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 DTC Information with a scan tool.

Did DTC P0342 fail this ignition?

--

Go to Step 4

Go to Step 3

3

  1. Turn OFF the ignition for 30 seconds.
  2. Start the engine.
  3. Operate the vehicle within the conditions for Running the DTC.

Did the DTC fail this ignition?

--

Go to Step 4

Go to Intermittent Conditions

4

  1. Turn OFF the ignition.
  2. Disconnect the camshaft position (CMP) sensor harness connector.
  3. Turn ON the ignition with the engine OFF.
  4. Important: Use a Test Lamp that measures between 25-30 ohms for this test.

  5. Probe the ignition 1 voltage circuit of the CMP sensor with a test lamp connected to a good ground.
  6. Measure the voltage from the probe of the test lamp to a good ground.

Is the voltage within 0.6 volts of the specified value?

B+

Go to Step 5

Go to Step 12

5

Connect a test lamp between the ignition 1 voltage circuit and the low reference circuit of the CMP sensor.

Does the test lamp illuminate?

--

Go to Step 6

Go to Step 13

6

Measure the voltage from the signal circuit of the CMP sensor to a good ground with a DMM.

Is the voltage within the specified range?

4.8-5.2V

Go to Step 8

Go to Step 7

7

Test the signal circuit of the CMP sensor for the following conditions:

    • High resistance
    • An open
    • A short to ground
    • A short to voltage

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 11

8

  1. Remove the CMP sensor. Refer to Camshaft Position Sensor Replacement .
  2. Inspect the CMP sensor for the following conditions:
  3. • Physical damage
    • Loose or improper installation
    • Wiring routed too closely to the secondary ignition components
    • Excessive air gap between the CMP sensor and the reluctor wheel
    • The CMP sensor coming in contact with the reluctor wheel
    • Foreign material passing between the CMP sensor and the reluctor wheel

Did you find and correct the condition?

--

Go to Step 16

Go to Step 9

9

Important: If the reluctor wheel is damaged, replace the CMP sensor.

Inspect the CMP sensor reluctor wheel for the following conditions:

    • Physical damage
    • Improper installation
    • Excessive play or looseness

Did you find and correct the condition?

--

Go to Step 16

Go to Step 10

10

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 16

Go to Step 14

11

Test for an intermittent and for a poor connection at the ECM. 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 16

Go to Step 15

12

  1. Repair the ignition 1 voltage circuit of the CMP sensor for one of the following conditions:
  2. • An open
    • A short to ground
    • High resistance
  3. Replace the fuse as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

13

Repair the low reference circuit of the CMP sensor for one of the following conditions:

    • An open
    • High resistance

Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

14

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

Did you complete the replacement?

--

Go to Step 16

--

15

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

--

Go to Step 16

--

16

  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.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 17

17

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK