Circuit Description
The engine control module (ECM) controls the ignition coils by pulsing the ignition control (IC) circuits, which triggers an ignition coil and fires the spark plug. The ECM controls the sequencing and the timing of each ignition coil. The ignition system consist of the following components:
| • | The six ignition coils |
| • | The crankshaft position (CKP) sensor |
| • | The four camshaft position (CMP) sensors |
| • | The ECM |
The ignition coils use the following circuits:
| • | An IC circuit |
| • | An ignition 1 voltage circuit |
| • | Two ground circuits |
Diagnostic Aids
| • | Use the J 35616-A/BT-8637 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector. |
| • | The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Engine Controls Component Views . |
| • | Inspect the ignition coils for aftermarket devices. An aftermarket device connected to the ignition coil circuits, may cause a condition with the ignition coils. |
| • | For an intermittent condition, refer to Intermittent Conditions . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The ignition coils for each bank are fused separately. If a fuse opens or the ignition 1 voltage circuit opens between the fuse and the splice, all the ignition coils for one bank of the engine would be inoperative. If the ground circuit opens at the engine block, the ignition coils would be inoperative for one bank of the engine.
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This step tests for an open or a high resistance in the ignition 1 voltage circuit of the ignition coil. If the DMM does not display near battery voltage there is an open or a high resistance in the circuit.
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This step determines if the ground circuit is open. If the circuit is open, the ignition coils would be inoperative for one bank of the engine.
-
This step determines if the ignition 1 voltage circuit is shorted to ground. If the fuse is open, the ignition coils would be inoperative for one bank of the engine.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 | Were you sent here from DTC P0300 or P0301-P0306? | -- | Go to Step 3 | Go to DTC P0300 or DTC P0301-P0306 |
3 |
Are any of the Misfire Current Counters incriminating? | -- | Go to Step 4 | Go to Intermittent Conditions |
Are all the misfire counters incriminating for one bank of the engine? | -- | Go to Step 7 | Go to Step 5 | |
Is the voltage at the specified value? | B+ | Go to Step 6 | Go to Step 9 | |
Connect the test lamp between the ignition 1 voltage circuit of the ignition coil and to each ground circuit of the ignition coil. Does the test lamp illuminate at each ground circuit? | -- | Go to Step 8 | Go to Step 10 | |
Test the ignition 1 voltage circuit for an open or high resistance at the splice of the affected bank of ignition coils. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 | |
8 | Test for an intermittent and for a poor connection at the ignition coil. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 |
9 |
Important: The ignition 1 voltage circuit is shared with other components. Disconnecting a component on the shared ignition 1 voltage circuit may isolate a shorted component. Review the electrical schematic and diagnose the shared circuits and components. Did you complete the repair? | -- | Go to Step 12 | -- |
10 | Repair the open or high resistance in the ground circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 12 | -- |
11 | Replace the ignition coil. Refer to the appropriate procedure: Did you complete the replacement? | -- | Go to Step 12 | -- |
12 |
Do any of the misfire counters increment? | -- | Go to Step 2 | Go to Step 13 |
13 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
