Circuit Description
There are two separate ignition module assemblies, one for each bank of cylinders. Each assembly contains an ignition control (IC) module and three ignition coils. Each IC module consists of the following circuits:
| • | Ignition 1 voltage |
| • | Ground |
| • | IC timing low reference |
| • | IC control circuits for cylinders 1-6 |
Each ignition coil connects directly to its spark plug via a short boot. The IC circuits transmit timing pulses from the powertrain control module (PCM) to the IC modules, which triggers the coils to fire the plugs in the correct sequence. The PCM monitors each IC circuit for improper voltage levels.
Conditions for Running the DTC
| • | The ignition voltage is between 9-17 volts. |
| • | The conditions are met for less than 1 second. |
Conditions for Setting the DTC
The PCM detects an incorrect voltage potential on the ignition control circuit.
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.
-
With no fault detected, the scan tool will display OK continuously. If a fault is detected, the display may fluctuate between OK and Fault, or display Fault continuously. If Fault is displayed, even momentarily, this should be considered fault present.
-
Refer to the system mechanization for the fuses which supply these circuits.
Step
| Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
Does the scan tool continuously indicate OK? | -- | Go to Intermittent Conditions | Go to Step 3 | |
3 | Check the ignition misfire current counters. Do the misfire current counters increment for all cylinders on one bank? | -- | Go to Step 4 | Go to Step 8 |
Inspect the ignition system fuses. Are the fuses OK? | -- | Go to Step 5 | Go to Step 12 | |
5 |
Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 13 |
6 | Connect a test lamp between the ignition 1 voltage circuit and the ground circuit in the ICM harness. Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 14 |
7 | Measure the resistance between the ground circuit and the low reference circuit in the ICM harness connector. Is the resistance less than or equal to the specified value? | 5 ohms | Go to Step 8 | Go to Step 15 |
8 |
Important: Remove the fuel pump fuse before proceeding. Running or cranking the engine with an ICM disconnected will cause excessive engine fueling if the fuel pump is not disabled.
Is the frequency within the specified range? | 2-20 Hz | Go to Step 19 | Go to Step 9 |
9 |
Is the voltage more than the specified value? | 1 V | Go to Step 18 | Go to Step 10 |
10 |
Is the resistance less than or equal to the specified value? | 5 ohms | Go to Step 11 | Go to Step 16 |
11 | Use the DMM in order to check for continuity between the ignition control circuit and ground. Does continuity exist? | -- | Go to Step 17 | Go to Step 24 |
12 | Check for a short to ground in the ICM ignition 1 voltage circuit. Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 21 |
13 | Repair the open in the ICM ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 26 | -- |
14 | Repair the open in the ICM ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 26 | -- |
15 | Repair the open or high resistance in the ICM low reference circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 26 | -- |
16 | Repair the open or high resistance in the ignition control circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 26 | -- |
17 | Repair the short to ground in the ignition control circuit . Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 26 | -- |
18 | Repair the ignition control circuit shorted to voltage. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 26 | -- |
19 |
Does continuity exist? | -- | Go to Step 20 | Go to Step 21 |
20 | Repair the ignition control circuits that are shorted together. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 26 | -- |
21 | Check for poor connections and terminal tension at the ICM harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 22 |
22 |
Do the LEDs flash for all 3 cylinders? | -- | Go to Intermittent Conditions | Go to Step 23 |
23 | Replace the ignition control module. Refer to Ignition Control Module Replacement . Did you complete the replacement? | -- | Go to Step 26 | -- |
24 | Check for poor connections and terminal tension at the PCM harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 25 |
25 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 26 | -- |
26 |
Does the DTC run and pass? | -- | Go to Step 27 | Go to Step 2 |
27 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
