For 1990-2009 cars

### Circuit Description

The ignition system uses individual ignition coil/module assemblies for each cylinder. The powertrain control module (PCM) controls the individual coils by transmitting timing pulses on the ignition control (IC) circuit of each ignition coil/module to enable a spark event. The PCM monitors each IC circuit for improper voltage levels. Each ignition coil/module has the following circuits:

• | An ignition voltage circuit

• | A ground

• | An IC circuit

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Turn OFF the ignition.
2. Remove the fuel pump relay.
3. Test for spark at each cylinder with a J 26792 Spark Tester.

Did you have spark on all cylinders?

--

Go to Step 3

Go to Step 5

3 | Does the spark tester indicate a bright blue spark on all cylinders? | -- | Go to Step 4 | Go to Step 9
4 |

1. Remove the spark plugs.
2. Examine the spark plugs for any abnormal conditions or damage. Refer to Spark Plug Inspection .

Are the spark plugs in good condition?

--

System OK

Go to Step 12

5 |

1. Turn OFF the ignition.
2. Disconnect the harness connector of the ignition coil/module for the affected cylinder.
3. Turn On the ignition, with the engine OFF.
4. Connect a test lamp from the ignition voltage circuit to the ground circuit of the ignition coil/module.

Does the test lamp illuminate?

--

Go to Step 7

Go to Step 6

6 | Connect a test lamp from the ignition voltage circuit of the ignition coil/module to a good ground. Does the test lamp illuminate? | -- | Go to Step 11 | Go to Step 10
7 |

1. Turn OFF the ignition.
2. Remove the fuse that supplies ignition voltage to the ignition coil/module.
3. Measure the resistance of ignition voltage circuit of the ignition coil/module from the fuse to the harness connector of the ignition coil/module with a DMM.

Is the resistance less than the specified value?

3 ohms

Go to Step 8

Go to Step 10

8 | Measure the resistance of ground circuit of the ignition coil/module from the harness connector of the ignition coil assembly to a good ground with a DMM. Is the resistance less than the specified value? | 3 ohms | Go to Step 9 | Go to Step 11
9 | Test for an intermittent and for a poor connection at the ignition coil/module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 13
10 | Repair the ignition voltage circuit of the ignition coil/module for one of the following conditions:

• | An open

• | A short to ground

• | High resistance

Refer to Wiring Repairs .

Did you complete the repair?

--

Go to Step 14

--

11 | Repair an open or high resistance in the ground circuit of the ignition coil/module. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 14 | --
12 | Replace the spark plugs. Refer to Spark Plug Replacement . Did you complete the replacement? | -- | Go to Step 14 | --
13 | Replace the ignition coil. Refer to Ignition Coil Replacement . Did you complete the replacement? | -- | Go to Step 14 | --
14 |

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

Does the vehicle operate normally?

--

System OK

Go to Step 2