Circuit Description
The ignition system on this engine uses an individual ignition coil for each cylinder. An ignition coil assembly consisting of three coils and an ignition control module (ICM), is located in the center of each cam cover. This arrangement allows the ignition coil to connect directly to the spark plug using only a boot. This eliminates the need for secondary ignition wires. There are separate ignition modules for bank 1 and for bank 2. Each module controls the three ignition coils for that bank of cylinders. The powertrain control module (PCM) controls ignition module operation. There are six ignition control (IC) circuits, one per cylinder, that connect the PCM and the ignition modules. The ignition modules also have a power feed, a chassis ground circuit, and a reference low circuit each. The PCM causes spark to occur by pulsing the IC circuit, which signals the ignition module to trigger the ignition coil and fire the spark plug. Sequencing and timing are PCM controlled.
Conditions for Running the DTC
| • | The ignition voltage is between 9.0-17.0 volts. |
| • | The conditions are met for less than 1.0 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 PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns the MIL Off after three consecutive drive trips that the diagnostic runs and does not fail. |
| • | A last test failed (current DTC) clears when the diagnostic runs and does not fail. |
| • | A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures. |
| • | Use a scan tool in order to clear the MIL/DTC. |
| • | Interrupting the PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Powertrain Control Module (PCM) Description , Clearing Diagnostic Trouble Codes. |
Diagnostic Aids
Notice: Use the connector test adapter kit J 35616-A for any test that
requires probing the following items:
• The PCM harness connectors • The electrical center fuse/relay cavities • The component terminals • The component harness connector
If the problem is intermittent, refer to Intermittent Conditions .
Test Description
Number(s) below refer to the step number(s) 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.
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Refer to the system mechanization for the fuses which supply these circuits.
Step
| Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Does the scan tool continuously indicate OK? | -- | Refer to Diagnostic Aids. | ||
3 | Is an entire bank of cylinders inoperative? | -- | ||
Are the ignition system fuses OK? | -- | |||
5 |
Does the test light illuminate? | -- | ||
6 | Connect test light J 35616-200 between the ignition feed circuit and the ground circuit in the Ignition Control module harness. Does the test light illuminate? | -- | ||
7 | Using DMM J 39200 measure the resistance between the ground circuit and the Reference Low circuit in the Ignition Control module harness connector. Does the DMM display the value shown (or lower)? | 5 Ohms | ||
8 |
Important: Remove the Fuel Pump fuse before proceeding. Running or cranking the engine with an Ignition Control module disconnected will cause excessive engine fueling if the fuel pump is not disabled.
Is the frequency within the specified range? | 2 - 20 Hz | ||
9 |
Is voltage greater than the specified value? | 1.0 V | ||
10 |
Does the DMM display the value shown (or lower)? | 5 Ohms | ||
11 | Using DMM J 39200 , check for continuity between the Ignition Control circuit and ground. Does the DMM display the value shown (or lower)? | 5 Ohms | ||
12 | Check for a short to ground in the Ignition Control module ignition feed circuit. Was a problem found and corrected? | -- | ||
13 | Repair open Ignition Control module ignition feed circuit. Is the action complete? | -- | -- | |
14 | Repair open Ignition Control module ground circuit. Is the action complete? | -- | -- | |
15 | Repair open/high resistance Ignition Control module Reference Low circuit. Is the action complete? | -- | -- | |
16 | Repair open/high resistance in the Ignition Control circuit. Is the action complete? | -- | -- | |
17 | Repair Ignition Control circuit shorted to ground. Is the action complete? | -- | -- | |
18 | Repair Ignition Control circuit shorted to voltage. Is the action complete? | -- | -- | |
19 |
Is continuity indicated? | -- | ||
20 | Repair Ignition Control circuits that are shorted together. Is the action complete? | -- | -- | |
21 | Check for poor connections/terminal tension at the Ignition Control module harness connector. Refer to Intermittents and Poor Connections Diagnosis . Was a problem found and corrected? | -- | ||
22 |
Do the LEDs flash for all three cylinders? | -- | Refer to Diagnostic Aids. | |
23 | Replace the Ignition Control module. Refer to Ignition Control Module Replacement . Is the action complete? | -- | -- | |
24 | Check for poor connections/terminal tension at the PCM harness connector. Refer to Intermittents and Poor Connections Diagnosis . Was a problem found and corrected. | -- | ||
25 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |
26 |
Does the scan tool indicate that this test ran and passed? | -- | ||
27 | Review Captured Info using the scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to the applicable DTC table | System OK |
