For 1990-2009 cars

### Circuit Description

The ignition control (IC) module has independent power and ground circuits. The circuits between the IC module and the powertrain control module (PCM) consist of the following circuits:

• | The IC timing signal

• | The IC timing control

• | The low-resolution engine speed signal

• | A low reference signal

The ignition control (IC) module sends 3x signals to the powertrain control module (PCM). The IC module controls the timing advance during engine cranking. The timing advance changes to PCM control after the following actions:

• | The PCM receives the second 3x signal.

• | The PCM applies 5 volts to the IC timing signal circuit.

• | The timing advance switches to PCM control.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. It is necessary to disconnect the 24 X crank sensor in order to ensure that the 7 X signal is read in the 3X reference parameter.

1. The J 26792 spark tester presents a more difficult load on the secondary ignition than a normal spark plug. If a miss or a hesitation is caused by a spark plug that is not firing, the spark tester should also not fire.

2. Use a 5 percent saltwater solution in a spray container to induce the voltage arcing to ground through faulty insulation of spark plug wires.

3. If the no spark condition follows the suspected coil, that coil is faulty. Otherwise, the ignition module is the cause of no spark. This test can also be performed by substituting a known good coil for the one causing the no spark condition.

Step | Action | Values | 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 | Attempt to start the engine. Does the engine start and continue to run ? | -- | Go to Intermittent Conditions | Go to Step 3
3 |

1. Disconnect the 24 X crank sensor.
2. With a scan tool, observe the 3X crank sensor parameter and crank the engine.

Does the scan tool indicate 3 X crank sensor signal present?

--

Go to Step 4

Go to Step 11

4 |

1. Reconnect the 24 X crank sensor.
2. With a J 26792 spark tester, test for spark at each cylinder.

Did you observe any non-sparking cylinders?

--

Go to Step 5

Go to Step 8

5 | Important: An arcing spark plug wire or an arcing ignition coil to the IC module may cause a stall or a no start condition.

1. Inspect and test the affected cylinder spark plug wires, the ignition coils, and the spark plugs for a short to ground or an arcing to ground. Refer to Spark Plug Wire Inspection .
2. If carbon tracking or corrosion is present, replace both components that are affected. Refer to Ignition Coil Replacement , and Spark Plug Wire Replacement .

Did you find and correct the condition?

--

Go to Step 23

Go to Step 6

6 |

1. Test affected spark plug wires for proper resistance. Refer to Ignition System Specifications .
2. Replace spark plug wires not near specification. Refer to Spark Plug Wire Replacement .

Did you find and correct the condition?

9868 ohms per m (3000 ohms per ft)

Go to Step 23

Go to Step 7

7 |

1. Switch the affected cylinder coil with a known good one.
2. If the fault follows the affected coil, then replace the coil. Refer to Ignition Coil Replacement .

Did you find and correct the condition?

--

Go to Step 23

Go to Step 15

8 |

1. Inspect the spark plug wires for proper routing and for the correct firing order.
2. If any spark plug wires are found to be misrouted, reroute as necessary. Refer to Spark Plug Wire Inspection .

Did you find and correct the condition?

--

Go to Step 23

Go to Step 9

9 |

1. With a DMM, test spark plugs for internal short to ground. Refer to Spark Plug Inspection .
2. Replace any grounded spark plugs that are found. Refer to Spark Plug Replacement .

Did you find and correct the condition?

--

Go to Step 23

Go to Step 10

10 |

1. Remove the spark plugs. Refer to Spark Plug Replacement .
2. Inspect spark plugs for damage. Refer to Spark Plug Inspection .
3. If any spark plugs are found to be bad, replace the affected spark plugs. Refer to Spark Plug Replacement .

Did you complete the replacement?

--

Go to Step 23

--

11 |

1. Reconnect the 24 X crank sensor.
2. Disconnect the IC module connectors.
3. Turn ON the ignition.
4. With a test lamp that is connected to a good ground, probe the IC module ignition 1 voltage circuit. Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 12

Go to Step 17

12 | Connect a test lamp between the IC module ignition 1 voltage circuit and the IC module ground circuit. Does the test lamp illuminate? | -- | Go to Step 13 | Go to Step 20
13 |

1. Disconnect the 7 X crankshaft sensor connector from the IC module.
2. With a test lamp connected to the battery positive voltage, probe both the CKP sensor 1 signal 7 X and the low reference 7 X circuits.

Does the test lamp illuminate when probing either circuits?

--

Go to Step 18

Go to Step 14

14 |

1. Connect a test lamp to ground.
2. Probe the CKP sensor 1 signal 7 X and the reference low 7 X circuits.

Does the test lamp illuminate when probing either circuits?

--

Go to Step 19

Go to Step 15

15 |

1. Ensure the battery voltage is within specifications.
2. Turn OFF the ignition.
3. Connect a DMM between the CKP sensor 1 signal circuit 7 X and the low reference 7X circuit at the IC module harness connector.
4. Crank the engine while observing AC duty cycle percent .

Does the DMM indicate AC duty cycle present?

--

Go to Step 21

Go to Step 16

16 |

1. Test the 7 X crank sensor circuits for the following conditions:

• | Opens

• | The CKP sensor 1 signal and the low reference 7 X circuits are shorted together.

2. Repair any damaged wiring. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 22

17 |

1. Repair the open or the short to ground in the IC module ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems.
2. Replace the fuse if necessary.

Did you complete the repair?

--

Go to Step 23

--

18 | Repair the short to ground in the circuit which illuminated the test lamp. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 23 | --
19 | Repair the short to voltage in the circuit which illuminated the test lamp. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 23 | --
20 | Repair the open in the IC module ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 23 | --
21 | Replace the IC module. Refer to Ignition Control Module Replacement . Did you complete the replacement? | -- | Go to Step 23 | --
22 | Replace the 7X crank sensor. Refer to Crankshaft Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 23 | --
23 |

1. Remove all test equipment.
2. Connect any disconnected components or any disconnected fuses.
3. Turn the ignition OFF for 30 seconds.
4. Start the engine and operate the vehicle.
5. Observe the MIL, the vehicle performance, and the driveability.

Does the vehicle operate correctly, without any MIL illumination and without any stored DTCs?

--

System OK

Go to Diagnostic Trouble Code (DTC) List