Refer to
Ignition Control
.
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 7X 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 to fire, leaving the remaining high voltage to fire the spark plug for the cylinder on the compression stroke.
During cranking, the ignition control module monitors the 7X crankshaft position sensor input for recognition of the sync signal. The sync signal is used to determine the correct cylinder pair to spark first. After the sync signal has been processed by the ignition control module, it sends a 3X reference signal to the PCM. The sync signal is used only by the ignition control module. It is used for spark synchronization at start-up only (not passed to the PCM).
When the ignition switch is turned to the ON position, the PCM commands all six injectors to open for one priming shot of fuel in all cylinders. After priming, the injectors are left OFF for the next six 3X reference signals from the ignition control module (two crankshaft revolutions). This allows each cylinder to use the fuel from the priming shot. During this waiting period, a cam signal will have been received by the PCM. Once true camshaft position is detected, the PCM operates the injectors sequentially. However, if the cam signal is not present at start-up, DTC P0341 will set and the PCM will start sequential fuel delivery in random pattern with a 1 in 6 chance that fuel delivery is correct.
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:
• | Poor connection or damaged harness. Inspect the PCM harness and connectors for improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness. |
• | Faulty Engine Coolant Temperature Sensor. Using a scan tool, compare Engine Coolant Temperature with Intake Air Temperature on a completely cool engine. Engine Coolant Temperature should be within 10° C of Intake Air Temperature. If not, replace the ECT sensor. Refer to Engine Coolant Temperature Sensor Replacement . |
Number(s) below refer to the step number(s) on the Diagnostic Table.
If spark is present, the ignition control module, coils, and ignition wires for cylinders 2, 4 and 6 are operating properly.
No spark from all of the coils indicate a problem with the ignition control module or 7X CKP sensor.
If resistance is within specifications, then a possible intermittent fault is present (refer to Diagnostic Aids).
Verifies the condition of the ignition wires for cylinders 1,3 and 5. An open ignition wire results in the loss of two cylinder. A no start may occur especially at colder ambient temperatures.
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.
Step | Action | Value(s) | Yes | No | ||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||||||||||||
2 | Select Failed last test with the scan tool. Are any of the following DTCs set? | -- | Diagnose the applicable DTC | |||||||||||||||||
3 |
Is the fuel pressure within the specified values and holding? | 284-325 kPa (41 - 47 PSI) | ||||||||||||||||||
4 | Is any fuel pressure indicated? | -- | Refer to Fuel System Diagnosis | |||||||||||||||||
5 |
Was a problem found? | -- | ||||||||||||||||||
6 |
Was a problem found? | -- | ||||||||||||||||||
7 |
Does the test light blink? | -- | ||||||||||||||||||
8 |
Was a problem found? | |||||||||||||||||||
Do the coils provide spark? | -- | |||||||||||||||||||
Do all of the coils fail to provide spark? | -- | |||||||||||||||||||
11 |
Was the fuse blown? | -- | ||||||||||||||||||
12 |
Was a problem found? | -- | ||||||||||||||||||
13 |
Is the resistance between the specified value? | 800-1,200 ohms | ||||||||||||||||||
14 |
Was a problem found? | -- | ||||||||||||||||||
15 |
Was a problem found? | -- | ||||||||||||||||||
16 |
Did any ignition coils require replacement? | Between 5000 and 8000 ohms (5K and 8K ohms). | ||||||||||||||||||
17 |
Did your inspection reveal a problem? | -- | ||||||||||||||||||
18 |
Does the test light blink while the engine is being cranked? | -- | ||||||||||||||||||
19 |
Did inspection reveal any faulty ignition wires? | -- | ||||||||||||||||||
Was a problem found? | -- | Refer to Diagnostic Aids | ||||||||||||||||||
21 |
Was a problem found? | |||||||||||||||||||
22 |
Did inspection reveal any faulty ignition wires? | -- | ||||||||||||||||||
Was a problem found? | -- | |||||||||||||||||||
24 | Remove all the spark plugs and inspect the electrodes. Does your inspection reveal any spark plugs exhibiting excessive fouling? | -- | ||||||||||||||||||
25 |
Was a problem found? | -- | Refer to Diagnostic Aids | |||||||||||||||||
26 | Repair engine mechanical problem. Refer to Engine Mechanical Diagnosis to diagnose the following conditions:
Is action complete? | -- | -- | |||||||||||||||||
27 | Replace the 7X crankshaft position sensor. Refer to Crankshaft Position Sensor Replacement . Is action complete? | -- | -- | |||||||||||||||||
28 | Replace the ignition coil(s) associated with the cylinders that did not have spark. Refer to Ignition Control Module Replacement . Is action complete? | -- | -- | |||||||||||||||||
29 | Replace the electronic ignition control module. Refer to Ignition Control Module Replacement . Is action complete? | -- | -- | |||||||||||||||||
Replace the PCM. Important: Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is action complete? | -- | -- |