Circuit Description
The electronic ignition system uses an individual ignition coil for each cylinder. The powertrain control module (PCM) controls the ignition operation through eight individual IC control circuits. Each bank of four ignition coils is connected to the PCM, power, or ground by the following circuits:
| • | Low Reference |
| • | Chassis ground |
| • | Ignition 1 voltage |
| • | The appropriate IC control circuit |
The PCM triggers an ignition coil by grounding the appropriate IC control circuit using information from the crankshaft position (CKP) and camshaft position (CMP) sensors.
Diagnostic Aids
Important: A missing CMP sensor may cause a long crank condition.
The CKP signal must be available for the engine to start. The CMP signal is not needed to start and operate the engine. The PCM can determine when a cylinder is on either the firing or exhaust stroke by the 24X signal. Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.For an intermittent condition, refer to Intermittent Conditions .
Test Description
The number below refer to the step number on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 | Are DTCs P0335, P0336, or P0351-P0358 set? | -- | Go to Step 3 | |
3 | Attempt to start the engine. Does the engine start and run? | -- | Go to Step 5 | Go to Step 4 |
Does the scan tool display the engine RPM? | -- | Go to Step 11 | Go to Step 25 | |
5 |
Do any of the misfire current counters increment? | -- | Go to Step 6 | Go to Diagnostic Aids |
6 |
Is adequate spark present? | -- | Go to Step 31 | Go to Step 7 |
7 | Measure Spark plug wire resistance. Refer to Spark Plug Wire Inspection . Does the resistance measure near the specified value? | 1,000ohms/ft | Go to Step 8 | Go to Step 30 |
8 |
Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 13 |
9 | Probe the ignition 1 voltage circuit at the ignition coil electrical connector to the ignition coil ground circuit using the test lamp. Refer to Probing Electrical Connectors in Wiring Systems. Does the test lamp illuminate? | -- | Go to Step 10 | Go to Step 16 |
10 | Probe the ignition 1 voltage circuit at the ignition coil electrical connector to the ignition coil low reference circuit using the test lamp. Refer to Probing Electrical Connectors in Wiring Systems. Does the test lamp illuminate? | -- | Go to Step 24 | Go to Step 20 |
11 |
Did you find and correct the condition? | -- | Go to Step 34 | Go to Step 12 |
12 | Repair the open in the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 34 | -- |
13 |
Does the test lamp illuminate? | -- | Go to Step 14 | Go to Step 15 |
14 | Repair the open ignition 1 voltage circuit between the splice and the ignition coil connector. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 34 | -- |
15 | Repair the open ignition 1 voltage circuit between the fuse block fuse and splice. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 34 | -- |
16 |
Does the test lamp illuminate? | -- | Go to Step 17 | Go to Step 19 |
17 |
Did you find and correct the condition? | -- | Go to Step 34 | Go to Step 18 |
18 | Repair the open ground circuit between the main 8-way connector and the ignition coil connector. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 34 | -- |
19 | Repair the open ground circuit between the ground and the main 8-way connector. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 34 | -- |
20 |
Does the test lamp illuminate? | -- | Go to Step 21 | Go to Step 23 |
21 |
Did you find and correct the condition? | -- | Go to Step 34 | Go to Step 22 |
22 | Repair the open low reference circuit between the main 8-way connector and the ignition coil connector. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 34 | -- |
23 | Repair the open low reference circuit between the powertrain control module (PCM) and the splice. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 34 | -- |
24 |
Did you find and correct the condition? | -- | Go to Step 34 | Go to Step 29 |
25 |
Is the voltage near the specified value? | B+ | Go to Step 26 | Go to Step 28 |
26 | Inspect for poor connections at the CKP sensor. 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 34 | Go to Step 27 |
27 | Replace the CKP sensor. Refer to Crankshaft Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 34 | -- |
28 | Test for a short to ground in the CKP sensor 12-volt reference circuit and in the CMP sensor 12-volt reference circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 34 | Go to Step 32 |
29 | Replace the ignition coil. Refer to Ignition Coil Replacement . Did you complete the replacement? | -- | Go to Step 34 | -- |
30 | Replace the spark plug wire. Refer to Spark Plug Wire Replacement . Did you complete the replacement? | -- | Go to Step 34 | -- |
31 | Replace the spark plug. Refer to Spark Plug Replacement . Did you complete the replacement? | -- | Go to Step 34 | -- |
32 | Inspect for poor connections 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 34 | Go to Step 33 |
33 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 34 | -- |
34 | Attempt to start the engine. Does the engine start and continue to run? | -- | Go to Step 35 | Go to Step 2 |
35 |
Does vehicle operate normally, with no MIL illumination and no stored DTCs? | -- | System OK | |
