For 1990-2009 cars

### Circuit Description

This ignition system does not use a conventional camshaft position (CMP) sensor that detects valve train position. The ignition control module (ICM) detects when #1 or #3 cylinder has fired on its compression stroke using sensing circuitry integrated within each coil. The sensing circuit detects the polarity and the strength of the secondary voltage output, the higher output is always at the event cylinder. The ICM sends a CMP signal to the powertrain control module (PCM) based on the voltage difference between the event and waste cylinder firing energy. This system is called compression sense ignition. By monitoring the CMP and crankshaft position (CKP) signals, the PCM can accurately time the operation of the fuel injectors. If the PCM receives an intermittent CMP signal from the ICM, the CMP Resync Counter on the scan tool will increment. When the PCM cannot use the information from the CMP signal, DTC P0340 will set.

### Conditions for Running the DTC

The engine is running.

### Conditions for Setting the DTC

The PCM does not detect any change in the CMP signal for 35 crankshaft revolutions (70 combustion events) when manifold absolute pressure (MAP) is at 55 kPa or greater.

### 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:

- | Low resistance in both the #1 and #3 secondary ignition circuits

- | High resistance in both the #4 and #2 secondary ignition circuits

- | An intermittent Crank Signal

• | An Intermittent crank signal will result in an interrupted cam signal and may set this DTC.

• | To locate an intermittent problem, use the scan tool to monitor CMP Active Counter parameter while running the engine. The counter should continuously count up to 255, then reset to zero. The counter will stop counting if a fault occurs in the cam signal circuit.

| If this DTC is determined to be intermittent, refer to Intermittent Conditions .

### Test Description

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

1. This step determines if the Ignition system is working correctly .

2. This step determines if the interconnect is bad or if a poor connection exists between the ICM and the Coil Cassette.

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. Install the scan tool.
2. Start and idle the engine.
3. Monitor the CMP Active Counter parameter with the scan tool.

Does the scan tool indicate the CMP active counter is incrementing?

--

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 ignition control module (ICM) electrical connector.
3. Connect a jumper wire from each terminal, except the CMP signal circuit, in the ICM harness connector to the corresponding terminal at the ICM. Refer to Using Connector Test Adapters in Wiring Systems.
4. Measure the DC duty cycle between the CMP signal circuit at the ICM and a good ground.
5. Start the engine.

Is the duty cycle within the specified range?

45-55%

Go to Step 6

Go to Step 5

5 |

1. Turn OFF the ignition.
2. Remove the jumper wires from the ICM.
3. Remove the ICM from the Ignition Coil Cassette. Refer to Ignition Control Module Replacement .
4. Remove the interconnect from between the coil cassette and the ICM.
5. Inspect the interconnect for a poor connection at the coil cassette or at the ICM.

Did you find and correct the condition?

--

Go to Step 11

Go to Step 7

6 | Test the CMP signal circuit for the following conditions:

• | An open

• | High resistance

• | 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 11

Go to Step 8

7 | Test for an intermittent and for a poor connection at the ICM. 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 11 | Go to Step 9
8 | 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 11 | Go to Step 10
9 | Replace the ICM. Refer to Ignition Control Module Replacement . Did you complete the replacement? | -- | Go to Step 11 | --
10 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 11 | --
11 |

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 12

12 | 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