Circuit Description
The ignition system on this engine uses an individual ignition control module (ICM) for each cylinder. The powertrain control module (PCM) controls the ignition system operation. The PCM controls each coil using one of 8 ignition control (IC) circuits. The PCM commands the IC circuit low when a spark event is requested. This causes the ICM to energize the ignition coil to create a spark at the spark plug. Each ICM has the following circuits:
| • | The ignition control circuit |
| • | The ignition 1 voltage circuit |
| • | A ground circuit |
| • | A reference low circuit |
The sequencing and timing are PCM controlled. This DTC sets when the IC circuit is out of range.
Conditions for Running the DTC
The engine is operating.
Conditions for Setting the DTC
The PCM detects the ignition control circuit is grounded, open, or shorted to voltage for less than 10 seconds.
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. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies the integrity of the IC circuit and the PCM output.
-
This step tests for a short to ground on the IC 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 DTC fail this ignition? | -- | Go to Step 3 | Go to Intermittent Conditions |
Is the frequency within the specified range? | 3-20 Hz | Go to Step 7 | Go to Step 4 | |
Measure the voltage at the ignition control circuit using the DMM. Is the voltage more than the specified value? | 1 V | Go to Step 13 | Go to Step 5 | |
5 |
Does the DMM indicate continuity? | -- | Go to Step 6 | Go to Step 14 |
6 | Test the respective IC circuit for a short to ground. Refer to Testing for Short to Ground in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 15 |
7 |
Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 9 |
8 | Probe the ground circuit of the ignition coil with a test lamp connected to B+. Refer to Troubleshooting with a Test Lamp in Wiring Systems. Does the test lamp illuminate? | -- | Go to Step 11 | Go to Step 10 |
9 | Repair the open in the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 17 | -- |
10 | Repair the open in the ground circuit for the ignition coil. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 17 | -- |
11 | Inspect for poor connections at the harness connector of the ignition coil. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 12 |
12 | Replace the ignition coil. Refer to Ignition Coil Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
13 | Repair the IC circuit for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 17 | -- |
14 | Repair the IC circuit for an open circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 17 | -- |
15 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 |
16 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the action? | -- | Go to Step 17 | -- |
17 |
Does the DTC run and pass? | -- | Go to Step 18 | Go to Step 2 |
18 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
