For 1990-2009 cars

### 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 ignition control (IC) 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 circuit

The PCM triggers an ignition coil by grounding the appropriate IC circuit using information from the crankshaft position (CKP) and camshaft position (CMP) sensors.

### Diagnostic Aids

Important: A missing CMP sensor signal 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. The 12 volt reference circuit for the CKP and CMP sensors are shared internally in the PCM. 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 numbers below refer to the step numbers on the diagnostic table.

1. Monitoring the misfire current counters determines if a fault is present.

2. A good indication that the fuse is open is all of the misfire current counters are incrementing on one side of the engine. Inspect the ignition positive voltage circuit for a grounded circuit. If the fuse is open and the ignition coil circuits are OK, inspect the injector circuits for being grounded.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Engine Controls Schematics
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls
2 |

1. Crank the engine.
2. Use a scan tool in order to observe the engine speed parameter.

Does the scan tool display the engine RPM?

--

Go to Step 3

Go to Step 25

3 | Are DTCs P0335, P0336, or P0351-P0358 set? | -- | Go to Diagnostic Trouble Code (DTC) List | Go to Step 4
4 |

1. Install a scan tool.
2. Idle the engine.
3. Use a scan tool in order to monitor all the Misfire Current counters on the misfire data list.

Do any of the Misfire Current counters increment?

--

Go to Step 5

Go to Diagnostic Aids

5 | Do the misfire current counters increment for most cylinders on one bank of the engine? | -- | Go to Step 11 | Go to Step 6
6 |

1. Inspect the spark plug wire for open circuits, cracks, or improper seating of terminals at the spark plug or coil before proceeding with test. Refer to Spark Plug Wire Inspection .
2. Inspect for spark at the plug with the J 26792 Spark Tester or equivalent while cranking. A few sparks, then nothing is considered no spark.

Is adequate spark present?

--

Go to Step 31

Go to Step 7

7 | Measure the spark plug wire resistance. Refer to Spark Plug Wire Inspection . Does the resistance measure near the specified value? | 460 720 ohms/ft | Go to Step 8 | Go to Step 30
8 |

1. Turn OFF the ignition.
2. Disconnect the ignition coil electrical harness connector that corresponds to the Misfire Current counter that was incrementing.
3. Turn ON the ignition, with the engine OFF.
4. Probe the ignition 1 voltage circuit at the ignition coil electrical connector with a test lamp connected to battery ground. Refer to Probing Electrical Connectors in Wiring Systems.

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 with a 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 with a test lamp. Refer to Probing Electrical Connectors in Wiring Systems. Does the test lamp illuminate? | -- | Go to Step 24 | Go to Step 20
11 |

1. Inspect for an open ignition coil fuse.
2. Locate and repair the ignition 1 voltage circuit for a grounded circuit if the fuse is open. Refer to Wiring Repairs in Wiring Systems.
3. Replace the fuse. Refer to General Electrical Diagnosis in Wiring Systems.

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 between the fuse block and the splice. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 34 | --
13 |

1. Disconnect the main ignition coil 8-way connector.
2. Probe the ignition 1 voltage circuit at the ignition coil main 8-way connector using the test lamp connected to battery ground. Refer to Probing Electrical Connectors in Wiring Systems.

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 |

1. Disconnect the main ignition coil 8-way connector.
2. Probe the coil ignition 1 voltage circuit to the ignition coil ground circuit at the ignition coil main electrical 8-way connector using the test lamp connected to the battery ground. Refer to Probing Electrical Connectors in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 17

Go to Step 19

17 |

1. Inspect for a poor connection at the main ignition coil 8-way electrical connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
2. Repair poor connections as necessary. Refer to Connector Repairs in Wiring Systems.

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 |

1. Disconnect the main ignition coil 8-way connector.
2. Probe the ignition 1 voltage circuit at the ignition coil main electrical 8-way 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 21

Go to Step 23

21 |

1. Inspect for a poor connection at the main ignition coil electrical 8-way connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
2. If a poor connection is found, repair as necessary. Refer to Connector Repairs in Wiring Systems.

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 PCM and the splice. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 34 | --
24 |

1. Inspect for poor connections at the ignition coil harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
2. Repair poor connections as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 34

Go to Step 29

25 |

1. Turn ON the ignition, with the engine OFF.
2. Disconnect the CKP sensor harness connector.
3. Measure the voltage from the CKP sensor 12-volt reference circuit and a good ground using the DMM.

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 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 |

1. Turn OFF the engine for 30 seconds.
2. Start the engine and operate the vehicle.
3. Observe the MIL, vehicle performance, and driveability.

Does the vehicle operate normally, with no MIL illumination and no stored DTCs?

--

System OK

Go to Diagnostic Trouble Code (DTC) List