GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2005 🢒 Montana - 4WD 🢒 Restraints 🢒 SIR 🢒 DTC P0340

Circuit Description

The camshaft position (CMP) sensor is a 1X sensor. It provides one digital ON/OFF signal, to the powertrain control module (PCM), per revolution of the camshaft. This information is used by the PCM to determine the position of the valve train relative to the crankshaft position (CKP). By monitoring the CMP and the CKP signals, the PCM can accurately time the operation of the fuel injectors. The PCM supplies 12 volts to the sensor on the 12-volt reference circuit and provides a ground on the low reference circuit. The CMP sensor provides signals to the PCM on the CMP sensor signal circuit. The PCM monitors the CMP sensor for errors. If the PCM does not receive a signal from the CMP sensor, DTC P0340 sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0340 Camshaft Position (CMP) Sensor Circuit

Conditions for Running the DTC
    • The engine is running for more than 3 seconds.
    • DTC P0340 runs continuously when the above condition is met.

Conditions for Setting the DTC

The PCM detects the following for every 2 engine revolution:

    • Six low resolution engine speed signals
    • Forty-eight medium resolution engine speed signals
    • Zero CMP sensor signals

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:

    •  Incorrect harness routing near secondary ignition components
    •  Ignition coil arcing to wiring harness or ignition control (IC) module--Inspect the ignition coils for cracks, for carbon tracking, or for other signs of damage.
    • Camshaft reluctor wheel damage
    • The sensor coming in contact with the reluctor wheel
    • Foreign material passing between the sensor and the reluctor wheel
    • Excessive camshaft end-play

If the condition is intermittent, refer to Intermittent Conditions .

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Inline Harness Connector End Views in Wiring Systems, 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

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2
  1. Start the engine.
  2. Observe the CMP sensor signal present parameter with a scan tool.

Does the scan tool indicate the CMP sensor signal is present?

--

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. Turn OFF the ignition.
  2. Disconnect the engine harness to fuel injector harness 16-way connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp to a good ground.
  5. Probe the 12-volt reference circuit of the camshaft position (CMP) sensor at the powertrain control module (PCM) side of the 16-way connector with the test lamp. Refer to Probing Electrical Connectors in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 9

5
  1. Jumper the 12-volt reference and the low reference circuits across the 16-way connector to their respective mates. Refer to Using Connector Test Adapters in Wiring Systems.
  2. 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 10

Go to Step 6

6
  1. Connect a test lamp to battery voltage.
  2. Turn ON the ignition, with the engine OFF.
  3. Probe the signal circuit of the CMP sensor at the PCM side of the 16-way harness connector with the test lamp. Refer to Probing Electrical Connectors in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 12

Go to Step 7

7
  1. Remove the CMP sensor signal terminal from the PCM side of the 16-way connector. Refer to Connector Repairs in Wiring Systems.
  2. Reconnect the 16-way connector.
  3. Start the engine.
  4. Observe the CMP Sensor Signal Present parameter on the scan tool.
  5. Tap the CMP sensor signal terminal with the test lamp that is still connected to B+.

Does the CMP sensor signal change when the test lamp contacts the signal circuit?

--

Go to Step 8

Go to Step 10

8
  1. Turn OFF the ignition.
  2. Remove the power steering pump. Refer to Power Steering Pump Replacement in Power Steering System.
  3. Visually inspect the CMP sensor circuits from the 16-way connector to the CMP sensor connector for the following conditions:
    4. • Damage
    • Corrosion
    • Opens
    • Shorts
    • Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 13

9

Test the CMP 12-volt reference circuit between the 16-way connector and the PCM 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 19

Go to Step 14

10

Test the CMP Low reference circuit between the 16-way connector and the PCM 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 19

Go to Step 14

11

Important: Disconnecting the PCM may remove the short from the circuit.

Test the CMP signal circuit between the 16-way connector and the PCM for an open or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 14

12

Important: Disconnecting the PCM may remove the short from the circuit.

Test the CMP signal circuit between the 16-way connector and the PCM for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 14

13

Test for an intermittent and poor connections at the CMP sensor connector. 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 19

Go to Step 15

14

Test for an intermittent and poor connections at the PCM harness connector. 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 19

Go to Step 18

15
  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 19

Go to Step 16

16
  1. Visually inspect the CMP sensor reluctor wheel for damage.
  2. If the CMP reluctor wheel is damaged, refer to Camshaft and Bearings Cleaning and Inspection in Engine Mechanical - 3.4L.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 17

17

Replace CMP sensor. Refer to Camshaft Position Sensor Replacement .

Did you complete the replacement?

--

Go to Step 19

--

18

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

Did you complete the replacement?

--

Go to Step 19

--

19
  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 20

20

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