For 1990-2009 cars

## Electronic Ignition (EI) System Diagnosis w/o Special Tool

### Circuit Description

Each ignition coil is responsible for supplying secondary energy to a pair of spark plugs. This is a waste spark ignition system. The ignition control (IC) signals output by the powertrain control module (PCM) are amplified by the ignition control module (ICM) in order to fire each coil. The spark events are triggered by the ICM, but the module has no influence on spark timing. The ICM is also responsible for detecting and supplying a CAM signal pulse to the PCM to be used for sequential fuel injection. This ignition system does not use a conventional camshaft position (CMP) sensor that detects valve train position. The ICM detects when #1 or #3 cylinder has fired on its compression stroke using sensing circuitry integrated within each coil. The sensing circuit detects the polarity and the strength of the secondary voltage output. The higher output is always at the event cylinder. The ICM sends a CAM signal to the PCM based on the voltage difference between the event and waste cylinder firing energy. This system is called compression sense ignition. By monitoring the CAM signals, the PCM can accurately time the operation of the fuel injectors.

This system consists of the following circuits:

• | Ignition 1 voltage

• | Ground

• | Camshaft position (CMP) sensor signal

• | IC timing control--2/3

• | IC timing control--1/4

### Diagnostic Aids

• | A small amount of resistance in the battery positive voltage circuit to the PCM may cause a no start. Test the battery positive voltage circuit for excessive resistance or corrosion. Refer to Wiring Repairs in Wiring Systems.

• | The PCM grounds will cause a no start only if all of them are not making a good connection. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

• | If the crankshaft position (CKP) sensor is loose the sensor may cause an intermitted no start by moving away from the reluctor wheel.

### Test Description

1. This step test for a short to voltage in the ignition circuit.

2. This step test for a short to voltage in the battery circuit.

#### Electronic Ignition Diagnosis

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. Observe the CKP Active Counter on the scan tool.

Does the CKP Active Counter increment?

--

Go to Step 6

Go to Step 3

3 |

1. Disconnect the CKP harness connector.
2. Turn ON the ignition, with the engine OFF.
3. Connect a DMM to the battery ground and each of the CKP sensor circuits at the CKP sensor harness connector.

Does the voltage measure more than the specified value?

3 V

Go to Step 4

Go to Step 9

4 | Test each CKP sensor circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 5
5 |

1. Turn OFF the ignition.
2. Retest each CKP sensor circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 25

Go to Step 23

6 |

1. Turn OFF the ignition.
2. Remove the fuel pump relay with the J 43244 Relay Puller Pliers.
3. Remove the ignition coil housing assembly. Refer to Ignition Coil Housing Replacement .

Important: Not grounding the ignition coil housing, may cause erratic spark.

4. Install a jumper wire with clips on both ends from the top of the ignition control module to ground.
5. Install the J 36012-A Ignition System Diagnostic Harness.
6. Install a J 26792 Spark Tester on #1 spark plug jumper wire.
7. Ground #4 (companion to #1) spark plug jumper wire.
8. Crank the engine with the remaining spark plug jumper wires connected.
9. Repeat the above steps by installing the spark tester on #4 and grounding #1. Do the same for #2 and #3 spark plugs making sure the companion wire is grounded.

Does the spark tester spark on all cylinders?

--

Go to Step 7

Go to Step 11

7 |

1. Turn OFF the ignition.
2. Inspect for malfunctioning spark plugs. Refer to Spark Plug Inspection .

Did you find and correct the condition?

--

Go to Step 25

Go to Step 8

8 | Inspect for basic engine problems. Refer to Symptoms - Engine Mechanical in Engine Mechanical. Did you find and correct any conditions? | -- | Go to Step 25 | Go to Diagnostic Aids
9 |

1. Reconnect the harness connector to the CKP sensor.
2. Disconnect the harness connector form the PCM.
3. Connect a DMM between the CKP sensor circuits.

Is the resistance within the specified value?

500-900 ohms

Go to Step 23

Go to Step 10

10 | Test the CKP Signal circuit and the Low Reference circuit for the following conditions:

• | An open

• | High resistance

• | Circuits shorted together

Did you find and correct the condition?

--

Go to Step 25

Go to Step 19

11 |

1. Turn OFF the ignition.
2. Remove the spark plug jumper wires.
3. Remove the ICM from the ignition coil housing. Refer to Ignition Control Module Replacement .
4. Confirm that the interconnect is connected to the ICM module.
5. Turn ON the ignition, with the engine OFF.
6. Use a DMM in order to measure the coil ignition positive voltage circuit at the ICM.

Does the voltage measure near the specified value?

Battery Voltage

Go to Step 12

Go to Step 13

12 |

1. Connect a test lamp between battery voltage and the affected ignition coil circuit at the ICM.
2. Crank the engine.

Does the test lamp blink?

--

Go to Step 22

Go to Step 15

13 |

1. Turn OFF the ignition.
2. Disconnect the ICM connector.
3. Turn ON the ignition, with the engine OFF.
4. Use a DMM in order to measure the ICM ignition 1 voltage circuit.

Does the voltage measure near the specified value?

--

Go to Step 21

Go to Step 14

14 | Test the ICM ignition 1 voltage circuit for the following:

• | An open

• | A short to ground

Did you find and correct the condition?

--

Go to Step 25

--

15 |

1. Turn OFF the ignition.
2. Disconnect the ICM connector.
3. Connect a DMM from the affected ignition coil control circuit to ground, set the DMM to AC voltage.
4. Crank the engine.

Does the voltage measure within the specified value?

0.5 V

Go to Step 17

Go to Step 16

16 | Test the affected ignition coil control circuit for the following:

• | An open

• | A short to ground

• | A short to voltage

• | A short between the timing control circuits

Did you find and correct the condition?

--

Go to Step 25

Go to Step 23

17 |

1. Turn OFF the ignition.
2. With a test lamp connected to battery positive, probe the ICM ground circuit.

Does the test lamp illuminate?

--

Go to Step 21

Go to Step 18

18 | Test the ICM ground circuit for the following:

• | An open

• | A short to voltage

Did you find and correct the condition?

--

Go to Step 25

--

19 | Inspect for poor connections at the CKP sensor. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you complete the repair? | -- | Go to Step 25 | Go to Step 20
20 |

1. Replace the CKP sensor. Refer to Crankshaft Position Sensor Replacement .
2. Perform the CKP variation learn procedure. Refer to Crankshaft Position System Variation Learn .

Did you complete the replacement?

--

Go to Step 25

--

21 | Replace the ICM. Refer to Ignition Control Module Replacement . Did you complete the replacement? | -- | Go to Step 25 | --
22 | Replace the ignition coil housing. Refer to Ignition Coil Housing Replacement . Did you complete the replacement? | -- | Go to Step 25 | --
23 | Inspect for poor connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you complete the repair? | -- | Go to Step 25 | Go to Step 24
24 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 25 | --
25 | Attempt to start the engine. Does the engine start and continue to run? | -- | Go to Step 26 | Go to Step 2
26 |

1. Turn OFF the ignition 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?

--

Go to Diagnostic Trouble Code (DTC) List

System OK

## Electronic Ignition (EI) System Diagnosis w/ Special Tool

### Circuit Description

Each ignition coil is responsible for supplying secondary energy to a pair of spark plugs. This is a waste spark ignition system. The ignition control (IC) signals output by the powertrain control module (PCM) are amplified by the ignition control module (ICM) in order to fire each coil. The spark events are triggered by the ICM, but the module has no influence on spark timing. The ICM is also responsible for detecting and supplying a CAM signal pulse to the PCM to be used for sequential fuel injection. This ignition system does not use a conventional camshaft position (CMP) sensor that detects valve train position. The ICM detects when #1 or #3 cylinder has fired on its compression stroke using sensing circuitry integrated within each coil. The sensing circuit detects the polarity and the strength of the secondary voltage output. The higher output is always at the event cylinder. The ICM sends a CAM signal to the PCM based on the voltage difference between the event and waste cylinder firing energy. This system is called compression sense ignition. By monitoring the CAM signals, the PCM can accurately time the operation of the fuel injectors.

This system consists of the following circuits:

• | Ignition 1 voltage

• | Ground

• | Camshaft position (CMP) sensor signal

• | IC timing control--2/3

• | IC timing control--1/4

### Diagnostic Aids

• | A small amount of resistance in the battery positive voltage circuit to the PCM may cause a no start. Test the battery positive voltage circuit for excessive resistance or corrosion. Refer to Wiring Repairs in Wiring Systems.

• | The PCM grounds will cause a no start only if all of them are not making a good connection. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

• | If the crankshaft position (CKP) sensor is loose the sensor may cause an intermitted no start by moving away from the reluctor wheel.

### Test Description

1. This step test for a short to voltage in the ignition circuit.

2. This step test for a short to voltage in the battery circuit.

#### Electronic Ignition Diagnosis

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. Observe the CKP Active Counter on the scan tool.

Does the CKP Active Counter increment?

--

Go to Step 6

Go to Step 3

3 |

1. Disconnect the CKP harness connector.
2. Turn ON the ignition, with the engine OFF.
3. Connect a DMM to the battery ground and each of the CKP sensor circuits at the CKP sensor harness connector.

Does the voltage measure more than the specified value?

3 V

Go to Step 4

Go to Step 9

4 | Test each CKP sensor circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 5
5 |

1. Turn OFF the ignition.
2. Retest each CKP sensor circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 25

Go to Step 23

6 |

1. Turn OFF the ignition.
2. Remove the fuel pump relay with the J 43244 Relay Puller Pliers.
3. Remove the ignition coil housing assembly. Refer to Ignition Coil Housing Replacement .

Important: Not grounding the ignition coil housing, may cause erratic spark.

4. Install a jumper wire with clips on both ends from the top of the ignition control module to ground.
5. Install the J 36012-A Ignition System Diagnostic Harness.
6. Install a J 26792 Spark Tester on #1 spark plug jumper wire.
7. Ground #4 (companion to #1) spark plug jumper wire.
8. Crank the engine with the remaining spark plug jumper wires connected.
9. Repeat the above steps by installing the spark tester on #4 and grounding #1. Do the same for #2 and #3 spark plugs making sure the companion wire is grounded.

Does the spark tester spark on all cylinders?

--

Go to Step 7

Go to Step 11

7 |

1. Turn OFF the ignition.
2. Inspect for malfunctioning spark plugs. Refer to Spark Plug Inspection .

Did you find and correct the condition?

--

Go to Step 25

Go to Step 8

8 | Inspect for basic engine problems. Refer to Symptoms - Engine Mechanical in Engine Mechanical. Did you find and correct any conditions? | -- | Go to Step 25 | Go to Diagnostic Aids
9 |

1. Reconnect the harness connector to the CKP sensor.
2. Disconnect the harness connector form the PCM.
3. Connect a DMM between the CKP sensor circuits.

Is the resistance within the specified value?

500-900 ohms

Go to Step 23

Go to Step 10

10 | Test the CKP signal circuit and the low reference circuit for the following conditions:

• | An open

• | High resistance

• | Circuits shorted together

Did you find and correct the condition?

--

Go to Step 25

Go to Step 19

11 |

1. Turn OFF the ignition.
2. Remove the spark plug jumper wires.
3. Remove the ignition control module from the ignition coil housing. Refer to Ignition Control Module Replacement .
4. Confirm that the interconnect is connected to the ICM module.
5. Turn ON the ignition, with the engine OFF.
6. Use a DMM in order to measure the coil ignition positive voltage circuit at the ICM.

Does the voltage measure near the specified value?

Battery Voltage

Go to Step 12

Go to Step 13

12 |

1. Remove the inner-connect from the ICM.
2. Connect a J 43298 Ignition Module Tester in place of the ignition coils.
3. Crank the engine.
4. Observe the 1-4 and 2-3 LEDs on the tester.

Does the appropriate 1-4 and 2-3 LEDs flash on the tester?

--

Go to Step 22

Go to Step 15

13 |

1. Turn OFF the ignition.
2. Disconnect the ICM connector.
3. Turn ON the ignition, with the engine OFF.
4. Use a DMM in order to measure the ICM ignition 1 voltage circuit.

Does the voltage measure near the specified value?

--

Go to Step 21

Go to Step 14

14 | Test the ICM ignition 1 voltage circuit for the following:

• | An open

• | A short to ground

Did you find and correct the condition?

--

Go to Step 25

--

15 |

1. Turn OFF the ignition.
2. Disconnect the ICM connector.
3. Connect a DMM from the affected ignition coil control circuit to ground, set the DMM to AC voltage.
4. Crank the engine.

Does the voltage measure within the specified value?

0.5 V

Go to Step 17

Go to Step 16

16 | Test the affected ignition coil control circuit for the following:

• | An open

• | A short to ground

• | A short to voltage

• | A short between the timing control circuits

Did you find and correct the condition?

--

Go to Step 25

Go to Step 23

17 |

1. Turn OFF the ignition.
2. With a test lamp connected to battery positive, probe the ICM ground circuit.

Does the test lamp illuminate?

--

Go to Step 21

Go to Step 18

18 | Test the ICM ground circuit for the following:

• | An open

• | A short to voltage

Did you find and correct the condition?

--

Go to Step 25

--

19 | Inspect for poor connections at the CKP sensor. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you complete the repair? | -- | Go to Step 25 | Go to Step 20
20 |

1. Replace the CKP sensor. Refer to Crankshaft Position Sensor Replacement .
2. Perform the CKP variation learn procedure. Refer to Crankshaft Position System Variation Learn .

Did you complete the replacement?

--

Go to Step 25

--

21 | Replace the ICM. Refer to Ignition Control Module Replacement . Did you complete the replacement? | -- | Go to Step 25 | --
22 | Replace the ignition coil housing. Refer to Ignition Coil Housing Replacement . Did you complete the replacement? | -- | Go to Step 25 | --
23 | Inspect for poor connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you complete the repair? | -- | Go to Step 25 | Go to Step 24
24 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 25 | --
25 | Attempt to start the engine. Does the engine start and continue to run? | -- | Go to Step 26 | Go to Step 2
26 |

1. Turn OFF the ignition 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?

--

Go to Diagnostic Trouble Code (DTC) List

System OK