Circuit Description
The electronic ignition system uses an individual ignition coil for each cylinder. There are 2 separate ignition module assemblies located in the camshaft cover of each cylinder bank. Each ignition module assembly contains an ignition control module and 4 ignition coils. Each ignition coil connects directly to a spark plug using a boot. This arrangement eliminates the need for secondary ignition wires. The ignition module assemblies receive power from a fused ignition feed. Both ignition module assemblies connect to chassis ground. A Reference Low circuit and 4 ignition control (IC) circuits connect each ignition module assembly to the powertrain control module (PCM). The PCM uses the individual IC circuits in order to control the coil sequencing and the spark timing for each ignition coil. The IC circuits transmit timing pulses from the PCM to the ignition control module in order to trigger the ignition coil and in order to fire the spark plug. The PCM monitors each IC circuit for improper voltage levels. If a short to ground occurs in the IC circuit, this diagnostic trouble code (DTC) will set.
Conditions for Running the DTC
The engine speed is more than 400 RPM.
Conditions for Setting the DTC
The PCM detects a short to ground on the IC circuit for less than 1 second.
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. |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics | |||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
2 |
Do the scan tool misfire counters increment for the suspect cylinder? | Go to Step 3 | Go to Intermittent Conditions |
3 |
Does the test lamp illuminate? | Go to Step 4 | Go to Step 6 |
4 |
Does the test lamp illuminate? | Go to Step 5 | Go to Step 7 |
5 | Repair the short to ground in the affected cylinder IC circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 8 | -- |
6 | Replace the ICM. Refer to Ignition Control Module Replacement - Bank 1 or Ignition Control Module Replacement - Bank 2 . Did you complete the replacement? | Go to Step 8 | -- |
7 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | Go to Step 8 | -- |
8 |
Does the DTC run and pass? | Go to Step 9 | Go to Step 2 |
9 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | System OK | |
