GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Kodiak C-Series Motorhome (Cutaway) C4/C5 🢒 DTC 🢒 DTC P0340

Circuit 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:

    • 5-volt reference
    • Low reference
    • CMP sensor signal

If the ECM does not see a CMP signal for more than 2 seconds, DTC P0340 will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0340 Camshaft Position (CMP) Sensor Circuit

Conditions for Running the DTC
    • The ignition is ON.
    • The engine is turning faster than 60 RPM.
    • DTC P0340 runs continuously when the above conditions are met.

Conditions for Setting the DTC

The ECM does not see a CMP sensor signal for more than 2 seconds.

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 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. Refer to Testing for Intermittent Conditions and Poor Connections and Inducing Intermittent Fault Conditions in Wiring Systems.
    • 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.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. If the engine starts and runs, the condition is suspected to be intermittent. If there is a condition with the CMP sensor circuit, the vehicle will not run.

    2.

  2. Inspect the CMP sensor for physical damage. The camshaft may damage the sensor.

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 - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Attempt to start the engine.

Does the engine start and run?

--

Go to Diagnostic Aids

Go to Step 3

3
  1. Turn OFF the ignition.
  2. Disconnect the camshaft position (CMP) sensor. Refer to Camshaft Position Sensor Replacement .
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the 5-volt reference circuit of the CMP sensor to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.

Does the DMM display a reading within the specified range?

4.8-5.2 V

Go to Step 5

Go to Step 4

4

Does the DMM display a reading above the specified value?

5.2 V

Go to Step 9

Go to Step 8

5
  1. Turn OFF the ignition.
  2. Disconnect the engine control module (ECM).
  3. Measure the resistance of the 5-volt reference circuit of the CMP sensor with a DMM. Refer to Circuit Testing in Wiring Systems.

Is the resistance above the specified value?

5 ohms

Go to Step 10

Go to Step 6

6
  1. Connect the ECM.
  2. Connect a jumper wire between each of the terminals in the CMP sensor harness connector and the corresponding terminals at the CMP sensor. Refer to Using Connector Test Adapters in Wiring Systems.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the low reference circuit of the CMP sensor at the jumper wire terminal to a good ground with a DMM. Refer to Measuring Voltage Drop in Wiring Systems.

is the voltage more than the specified value?

0.2 V

Go to Step 11

Go to Step 7

7
  1. Turn OFF the ignition.
  2. Remove the jumper wires from the CMP sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the Cam Signal Present parameter with a scan tool.
  5. Momentarily and repeatedly probe the signal circuit of the CMP sensor with a test lamp that is connected to battery voltage.

Does the Cam Signal Present parameter change when the test lamp contracts the signal circuit?

--

Go to Step 12

Go to Step 13

8

Test the CMP sensor 5-volt reference circuit for an open or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 15

9

Test the CMP sensor 5-volt reference 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 18

Go to Step 15

10

Repair the high resistance in the CMP sensor 5-volt reference circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 18

--

11

Test the CMP sensor low reference circuit for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 15

12

Test the CMP sensor signal circuit for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 14

13

Test the CMP sensor signal for the following conditions:

    • An open
    • A short to ground
    • A short to voltage
    • High resistance
        Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 15

14

Inspect for poor connections at the CMP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 16

15

Inspect for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 17

16

Important: Inspect the CMP sensor for physical damage before replacing.

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

Did you complete the replacement?

--

Go to Step 18

--

17

Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 18

--

18
  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 19

19

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

System OK