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 the cylinders 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 engine control module (ECM) 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 ECM can accurately sequence the fuel injectors. If the ECM does not receive a CMP signal from the ICM, DTC P0340 sets.
Conditions for Running the DTC
| • | The engine is running. |
| • | The manifold absolute pressure (MAP) is more than 30 kPa. |
Conditions for Setting the DTC
The ECM does not detect any change in the CMP sensor signal for 107 crankshaft revolutions when MAP is at 30 kPa or more.
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
| • | An Intermittent crank signal will result in an interrupted cam signal and may set this DTC. |
| • | The following conditions may cause this DTC to set: |
| - | High resistance in the #1 secondary ignition system |
| - | Low resistance in the #4 secondary ignition system |
| - | Corroded or loose #1 or #4 secondary ignition components |
| • | 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.
-
If CYL #1 and/or CYL #4 Misfire Counters are incrementing there is a condition within the secondary ignition system that effects the Camshaft Position signal circuit.
-
The ECM supplies 5 volts on the camshaft position signal circuit. This step determines if the ECM is supplying the correct voltage on the circuit.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 |
Does the CMP Resync Counter parameter increment to 14 and then reset to 0 continuously? | -- | Go to Step 3 | Go to Step 4 |
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids |
Observe the Misfire Current CYL # 1 and CYL # 4 counters with a scan tool. Is CYL #1 and/or CYL #4 Misfire counters counting up? | -- | Go to DTC P0300 | Go to Step 5 | |
5 |
Is the Duty Cycle within the specified range? | 45-55% | Go to Step 6 | Go to Step 10 |
Is the voltage within the specified range? | 4-6 V | Go to Step 8 | Go to Step 7 | |
7 | Is the voltage above the specified range? | 4-6 V | Go to Step 11 | Go to Step 8 |
8 |
Is the resistance within the specified range? | 0-5 ohms | Go to Step 9 | Go to Step 12 |
9 |
Is the resistance at the specified value? | OL | Go to Step 16 | Go to Step 13 |
10 |
Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 14 |
11 | Test the camshaft position 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 18 | Go to Step 16 |
12 | Test the camshaft position signal 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 18 | Go to Step 16 |
13 | Test the camshaft position signal circuit 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 18 | Go to Step 16 |
14 | 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 18 | Go to Step 15 |
15 | Replace the ICM. Refer to Ignition Control Module Replacement . Did you complete the replacement? | -- | Go to Step 18 | -- |
16 | 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 18 | Go to Step 17 |
17 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 18 | -- |
18 |
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? | -- | System OK | |
