Circuit Description
The ignition control (IC) module has independent power and ground circuits. The circuits between the IC module and the powertrain control module (PCM) consist of the following circuits:
| • | The IC timing signal |
| • | The IC timing control |
| • | The low-resolution engine speed signal |
| • | A low reference signal |
The ignition control (IC) module sends 3x signals to the powertrain control module (PCM). The IC module controls the timing advance during engine cranking. The timing advance changes to PCM control after the following actions:
| • | The PCM receives the second 3x signal. |
| • | The PCM applies 5 volts to the IC timing signal circuit. |
| • | The timing advance switches to PCM control. |
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
| • | The PCM detects an open circuit in the IC signal circuit. |
| • | The condition is present for 300 3X reference periods, 106 crankshaft revolutions. |
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 engine will start and may run in bypass mode timing. |
| • | If the condition is intermittent, refer to Intermittent Conditions. |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Did the DTC fail this ignition? | -- | Go to Step 3 | Go to Intermittent Conditions |
3 |
Is the voltage more than the specified value? | 4.9 V | Go to Step 4 | Go to Step 5 |
4 | Is the voltage more than the specified value? | 6 V | Go to Step 6 | Go to Step 9 |
5 |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 8 |
6 | Test the IC timing signal circuit between the ICM and the powertrain control module (PCM) 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 13 | Go to Step 12 |
7 | Test the IC timing signal circuit between the ICM 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 13 | Go to Step 12 |
8 | Test the IC timing signal circuit between the ICM and the PCM for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 |
9 | Test for an intermittent and poor connections 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 13 | Go to Step 11 |
10 | Test for an intermittent and 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 13 | Go to Step 12 |
11 | Replace the ICM. Refer to Ignition Control Module Replacement. Did you complete the replacement? | -- | Go to Step 13 | -- |
12 | Replace the PCM. Refer to Powertrain Control Module Replacement. Did you complete the replacement? | -- | Go to Step 13 | -- |
13 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 14 |
14 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
