For 1990-2009 cars

Refer to

#### Ignition Control Module

VIN K Fuel Conrol
OBD II Symbol Description Notice
MIL Control
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
.

### Circuit Description

The electronic ignition system uses a waste spark method of spark distribution. In this type of ignition system, the ignition control module triggers the correct coil based on the sync signal received from the crankshaft position sensor, resulting in both spark plugs connected to the coil firing at the same time. The spark plug for the cylinder on the exhaust stroke requires a lower energy requirement in order to fire, leaving the remaining high voltage to fire the spark plug for the cylinder on the compression stroke.

During crank, the ignition control module monitors the crankshaft position (CKP) sync signal. The CKP sync signal is used to determine the correct cylinder pair to fire first. The CKP sync signal is used only by the ignition control module in order to initiate the ignition coil firing sequence. It is not passed to the PCM. After the ignition control module processes the CKP sync signal, the ignition control module monitors the 18X CKP signal and sends 18X and 3X reference pulses to the PCM. When the PCM receives these pulses, the PCM will command all six injectors in order to allow a priming shot of fuel for all the cylinders. After the priming, the injectors are left OFF during the next six 3X reference pulses from the ignition control module. This allows each cylinder a chance to use the fuel from the priming shot. During this waiting period, the PCM receives a camshaft position signal pulse. The camshaft position signal allows the PCM to operate the injectors sequentially, based on camshaft position. If the camshaft position signal is not present at start-up, the PCM will begin sequential fuel delivery with a 1 in 6 chance that fuel delivery is correct.

### Diagnostic Aids

An intermittent may be caused by a poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check for the following items:

• | A shorted camshaft position sensor

| An internally-shorted camshaft position sensor can cause an Engine Cranks but Will not Run condition. If the diagnostic table indicates a short to ground in the sensor ignition positive voltage circuit, disconnect the camshaft position sensor and attempt to start the vehicle. If the vehicle starts with the camshaft position sensor disconnected, a shorted camshaft position sensor is indicated.

• | A poor connection or a damaged harness

| Inspect the PCM harness and connectors for improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connections, and a damaged harness.

• | A malfunctioning engine coolant temperature sensor

| Using a scan tool, compare the engine coolant temperature with the intake air temperature on a completely cool engine. The engine coolant temperature should be within 10°C (50°F) of the intake air temperature. If it is not, replace the ECT sensor.

• | The throttle position (TP) sensor

| If the TP angle is more than 80 percent, the PCM may operate in clear flood mode. The PCM will not allow fuel delivery while operating in clear flood mode.

### Test Description

Number(s) below refer to the Step number(s) on the Diagnostic Table:

1. A blinking test light verifies that the PCM is monitoring the 3X and 18X reference signals and is capable of activating the injectors

2. The crankshaft position sensor and fuel injectors have been verified as functioning properly. A fuel pressure test will separate the diagnostic path into either a fuel pressure related malfunction or an ignition system malfunction.

3. By using a J 26792 Spark Tester to test for spark on the plug wires, each ignition coil's ability to produce at least 25,000 volts is verified.

4. If any of the ignition coil towers exhibit carbon tracking, replace the ignition coil and the associated ignition wire.

   If any ignition wire exhihits carbon tracking inside the boot that connects to the coil tower, replace the ignition wire and the associated coil.

5. By testing the problem coil's control circuit with a test light, a determination can be made as to the problem coil malfunctioning or the ignition control module's internal control circuit for the affected coil being the cause of the condition

6. An internally shorted camshaft position sensor can cause an engine cranks but will not run condition. If the diagnostic table indicates a short to ground in the sensor ignition positive voltage circuit, disconnect the camshaft position sensor and attempt to start the vehicle. If the vehicle starts with the camshaft position sensor disconnected, a shorted camshaft position sensor is indicated.

7. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

#### Engine Cranks But Will Not Run

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to the Powertrain On Board Diagnostic (OBD) System Check
2 | Important:: Before proceeding with this diagnostic Table, ensure that the vehicle battery is fully charged. Important:: If any the following DTCs are stored as failed since code clear, diagnose the DTC(s) before continuing with this table:

• | DTC P0123 Throttle Position (TP) Sensor Circuit High Voltage

• | DTC P0601 Control Module Read Only Memory (ROM)

• | DTC P0602 Control Module Not Programmed

• | DTC P1629 Theft Deterrent Fuel Enable Signal Not Received

1. Check the fuse for the electronic ignition control module ignition positive voltage circuit.
2. Check the fuse for the fuel injector ignition positive voltage circuit.
3. If either fuse is blown, locate and repair short to ground in the affected ignition positive voltage circuit. Refer to Repair Procedures in Electrical Diagnosis.

Was a problem found?

--

Go to the Powertrain On Board Diagnostic (OBD) System Check

Go to Step 3

3 | Observe Engine Speed display on the scan tool while cranking the engine. Is engine RPM indicated? | -- | Go to Step 4 | Go to Step 23
4 |

1. Disconnect all of the fuel injector connectors and install a J 34730-2A injector test light at each injector harness connector.
2. Turn ON the ignition switch, observe the injector test lights

Are any of the injector test lights ON?

--

Go to Step 16

Go to Step 5

5 | Crank the engine while monitoring the injector test lights. Do all of the injector test lights blink continuously while the engine is being cranked? (If not, record which injector test lights did not blink.) | -- | Go to Step 6 | Go to Step 18
6 |

1. Turn OFF the ignition switch.
2. Install a fuel pressure gage at the fitting on the fuel rail.
3. Turn ON the ignition switch.
4. Observe the fuel pressure gauge.

Is the fuel pressure within the specified values and holding?

333-375 kPa

(48-55 psi)

Go to Step 8

Go to Step 7

7 | Is any fuel pressure indicated? | -- | Go to Fuel System Pressure Test Go to Fuel System Pressure Test | Go to Fuel Pump Electrical Circuit Diagnosis Go to Fuel Pump Electrical Circuit Diagnosis
8 |

1. Test the fuel for contamination. Refer to Alcohol/Contaminants-in-Fuel Test .
2. If a problem is found, clean the fuel system and correct the contaminated fuel condition as necessary.

Was a problem found?

--

Go to the Powertrain On Board Diagnostic (OBD) System Check

Go to Step 9

9 |

1. Install a J 26792 spark tester at the spark plug end of an ignition wire.
2. Jumper the spark plug end of the companion cylinder ignition wire to engine ground. The companion cylinder is the cylinder that shares the same ignition coil (i.e., 1/4; 2/5; 3/6).
3. Crank the engine while observing the spark tester. A crisp, blue spark should be observed.
4. Repeat the above test for each ignition wire, noting any cylinders that do not have adequate spark.

Is adequate spark present at all cylinders?

--

Go to Step 10

Go to Step 11

10 |

1. Remove the spark plugs from all the cylinders.
2. Visually inspect the spark plug electrodes.

Did your inspection reveal any spark plugs exhibiting excessive fouling?

--

Go to Engine Mechanical Diagnosis in Engine General Information

Go to Step 35

11 | Is spark present at any ignition wires? | -- | Go to Step 12 | Go to Step 39
12 |

1. Remove and visually/physically inspect the ignition coil(s) and the the ignition wires associated with the cylinders that did not have spark. Ensure that the ignition wires, boots, coils and coil towers are free of cracks and carbon tracking.
2. If a problem is found, replace damaged ignition wire(s) and/or ignition coil(s) as necessary.

• | Refer to Ignition Control Module Replacement .

• | Refer to On-Vehicle Service - Secondary Wiring in Ignition System.

Was a problem found?

--

Go to the Powertrain On Board Diagnostic (OBD) System Check

Go to Step 13

13 |

1. Measure the ignition coil secondary resistance.
2. If any resistance is outside the specified values, replace malfunctioning ignition coil(s) as necessary. Refer to Ignition Control Module Replacement .

Was a problem found?

5K-8K ohms

(5000-8000 ohms)

Go to the Powertrain On Board Diagnostic (OBD) System Check

Go to Step 14

14 |

1. Measure the resistance of the ignition wires associated with the cylinders that did not have spark.
2. Replace any ignition wire(s) that measure greater than the specified value. Refer to On-Vehicle Service in Ignition System.

Was a problem found?

30 K ohms

(30,000 ohms)

Go to the Powertrain On Board Diagnostic (OBD) System Check

Go to Step 15

15 |

1. Connect a test light across the ignition module primary circuit (between the electronic ignition control module terminals) for coil(s) associated with the cylinders which did not have spark.
2. Observe the test light while cranking the engine.

Does the test light blink continuously while the engine is being cranked?

--

Go to Step 38

Go to Step 39

16 |

1. Turn OFF the ignition switch.
2. Disconnect the PCM.
3. Turn ON the ignition switch.
4. Observe the injector test lights.

Are any of the injector test lights ON?

--

Go to Step 17

Go to Step 37

17 | Locate and repair short to ground in the injector control circuit(s) associated with the injector test light(s) that stayed ON. Refer to Repair Procedures in Electrical Diagnosis. Is action complete? | -- | Go to the Powertrain On Board Diagnostic (OBD) System Check | --
18 | Did any of the injector test lights blink continuously? | -- | Go to Step 19 | Go to Step 21
19 |

1. Disconnect the injector test lights that did not blink when the engine was cranked in Step 5 .
2. Turn ON the ignition switch.
3. Probe the ignition positive voltage circuit at each injector connector with a test light to ground.

Is the test light ON at all of the injector connectors?

--

Go to Step 20

Go to Step 33

20 |

1. Turn OFF the ignition switch.
2. Disconnect the PCM.
3. Check the affected injector control circuits for an open.
4. If a problem is found, repair as necessary. Refer to Repair Procedures in Electrical Diagnosis.

Was a problem found?

--

Go to the Powertrain On Board Diagnostic (OBD) System Check

Go to Step 37

21 | Probe the fuel injector ignition positive voltage circuit at any injector connector with a test light to ground. Is the test light ON? | -- | Go to Step 22 | Go to Step 33
22 |

1. Install an injector test light at any injector harness connector.
2. Turn OFF the ignition switch.
3. Disconnect the ignition control module harness connector.
4. Turn ON the ignition switch.
5. Connect a test light to B+.
6. Repeatedly touch the test light to the 3X reference circuit at the ignition control module harness connector while observing the injector test light.

Does the injector test light blink?

--

Go to Step 24

Go to Step 32

23 |

1. Turn OFF the ignition switch.
2. Disconnect the ignition control module harness connector.
3. Turn ON the ignition switch.
4. Probe the ignition control module ignition positive voltage circuit at the harness connector with a test light to ground.

Is the test light ON?

--

Go to Step 24

Go to Step 34

24 |

1. Turn OFF the ignition switch.
2. Using the proper jumper from the J 35616 test connector adapter kit, connect a fused jumper between the sensor positive voltage circuit at the ignition control module harness connector and B+.
3. Connect a second jumper between the sensor ground circuit at the ignition control module harness connector and engine ground.
4. Connect a J 39200 Digital Multimeter to measure voltage between the CKP sync signal circuit at the ignition control module harness connector and B+.
5. Observe voltage while cranking the starter.

Is the voltage between the specified values?

1 V-3 V

Go to Step 28

Go to Step 25

25 | Is the voltage greater than the specified value? | 3 V | Go to Step 26 | Go to Step 27
26 |

1. Disconnect the crankshaft position sensor.
2. Probe the CKP sync signal circuit with a test light to B+.
3. If the test light is ON, locate and repair short to ground in the CKP sync signal circuit. Refer to Repair Procedures in Electrical Diagnosis.

Was a problem found?

--

Go to the Powertrain On Board Diagnostic (OBD) System Check

Go to Step 40

27 |

1. Check the following crankshaft position sensor circuits:

• | The CKP sync signal circuit for an open or short to voltage.

• | The sensor ground circuit for an open.

• | The sensor positive voltage circuit for an open or short to ground (including camshaft position sensor shorted - refer to Camshaft Position Sensor Replacement ).

2. If a problem is found, repair it as necessary.
3. Refer to Repair Procedures in Electrical Diagnosis.

Was a problem found?

--

Go to the Powertrain On Board Diagnostic (OBD) System Check

Go to Step 40

28 |

1. Connect the digital multimeter to measure voltage between the CKP 18X signal circuit at the ignition control module connector and B+.
2. Observe the voltage while cranking the starter.

Is voltage between the specified values?

5-7V

Go to Step 39

Go to Step 29

29 | Is the voltage greater than the specified value? | 7 V | Go to Step 30 | Go to Step 31
30 |

1. Disconnect the crankshaft position sensor.
2. Probe the CKP 18X signal circuit with a test light to B+.
3. If the test light is ON, locate and repair short to ground in the CKP 18X signal circuit. Refer to Repair Procedures in Electrical Diagnosis.

Was a problem found?

--

Go to the Powertrain On Board Diagnostic (OBD) System Check

Go to Step 40

31 |

1. Check the CKP 18X signal circuit for an open or short to voltage
2. If the CKP 18X signal circuit is open or shorted, repair as necessary. Refer to Repair Procedures in Electrical Diagnosis .

Was a problem found?

--

Go to the Powertrain On Board Diagnostic (OBD) System Check

Go to Step 40

32 |

1. Turn OFF the ignition switch.
2. Disconnect the PCM.
3. Check the 3X reference circuit for an open or short circuit.
4. If a problem is found, repair as necessary. Refer to Repair Procedures in Electrical Diagnosis.

Was a problem found?

--

Go to the Powertrain On Board Diagnostic (OBD) System Check

Go to Step 37

33 | Locate and repair the open in the fuel injector ignition positive voltage circuit. Refer to Repair Procedures in Electrical Diagnosis. Is action complete? | -- | Go to the Powertrain On Board Diagnostic (OBD) System Check | --
34 | Locate and repair open in the ignition control module ignition positive voltage circuit. Refer to Repair Procedures in Electrical Diagnosis. Is action complete? | -- | Go to the Powertrain On Board Diagnostic (OBD) System Check | --
35 |

1. Refer to Diagnostic Aids to check for the following conditions:

• | Stuck TP sensor.

• | Skewed ETC sensor.

• | Skewed or unresponsive MAP sensor.

2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to the Powertrain On Board Diagnostic (OBD) System Check

Go to Step 36

36 | Repair the engine mechanical problem. Refer to Engine Mechanical Diagnosis in Engine General Information to diagnose the following conditions:

• | Bent push rods.

• | Malfunctioning or incorrect camshaft.

• | Leaking or sticky valves or rings.

• | Excessive valve deposits.

• | Loose or worn rocker arms.

• | Weak valve springs.

• | Incorrect valve timing.

• | Leaking head gasket.

Is action complete?

--

Go to the Powertrain On Board Diagnostic (OBD) System Check

--

37 | Replace the PCM Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is action complete? | -- | Go to the Powertrain On Board Diagnostic (OBD) System Check | --
38 | Replace the ignition coil(s) associated with the cylinders that did not have spark. Refer to Ignition Control Module Replacement . Is action complete? | -- | Go to the Powertrain On Board Diagnostic (OBD) System Check | --
39 | Replace the electronic ignition control module. Refer to Ignition Control Module Replacement . Is action complete? | -- | Go to the Powertrain On Board Diagnostic (OBD) System Check | --
40 | Replace the crankshaft position sensor. Refer to Crankshaft Position Sensor Replacement Is action complete? | -- | Go to the Powertrain On Board Diagnostic (OBD) System Check | --