Engine Cranks But Does Not Run
il:
Circuit Description
The electronic Ignition System uses a coil-at-plug method of spark distribution. In this type of Ignition System, the Powertrain Control Module ([1][2]PCM) triggers the correct driver inside the ignition control module (ICM), which then triggers the correct ignition coil based on the 58X signal received from the Crankshaft position sensor (CKP). The Spark Plug connected to the coil fires when the ICM opens the ground circuit for the coil's primary circuit.
During crank, the [1][2]PCM monitors the CKP 58X signal. The CKP signal is used to determine which cylinder will fire first. After the CKP 58X signal has been processed by the PCM, it will command all six injectors to allow a priming shot of fuel for all the cylinders. After the priming, the injectors are left "OFF" during the next six 58X reference pulses from the CKP. This allows each cylinder a chance to use the fuel from the priming shot. During this waiting period, a camshaft position (CMP) signal pulse will have been received by the PCM. The CMP 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. The Engine will run without a CMP signal, but will set a DTC code.
Diagnostic Aids
An intermittent problem 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 [1][2]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 (ECT) 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.
Test Description
Number(s) below refer to the step number(s) in the Diagnostic Test:
5. An obvious cause of low fuel pressure would be an empty fuel tank.
6. The engine will easily start and run if a few injectors are disabled. It is not necessary to test all injectors at this time since this step is only a test to verify that all of the injectors have not been disabled by fuel contamination.
7. A blinking test light verifies that the [1][2]PCM is monitoring the 58X crankshaft reference signal and is capable of activating the injectors. If there is an open or shorted driver circuit, DTCs 201-206 and a misfire DTC 301-306 should be set.
19. By using a spark tester, each ignition coil's ability to produce 25,000 volts is verified.
25. If there is an open or shorted driver circuit, DTCs 201-206 and a misfire DTC 301-306 should be set. All six injector driver circuits can be checked at one time without removing the intake manifold if a J 39021-95 test light is available. This is the alternative procedure:
- With the ignition "OFF," disconnect the gray connector located at the rear of the air filter, attached to a bracket on the purge canister.
- Connect test light J 39021-65 to the connector. Do any of the lights constantly illuminate or fail to blink when the engine is cranked? If so, repair the short or open circuit, or replace the [1][2]PCM if indicated.
This procedure only tests the driver circuit as far as the test connection, so step 31 is added to test the circuit all the way to the injector.
Diagnostic Test
1. Was the "On-Board Diagnostic (OBD) System Check" performed?
[YES] Go to Step 2.
[NO] Go to OBD System Check. Initial Inspection
2. a. Check the 15-A ignition coil fuse, the 15-A Engine device fuse, and the 15-A [1][2]PCM fuse.
b. Was a fuse blown?
[YES] Go to Step 3.
[NO] Go to Step 4.
3. a. Check for a short to ground and replace the fuse.
b. Is the action complete?
[YES] Verify repair.
4. a. Ignition "OFF," install a fuel pressure gauge at the test fitting on the fuel supply line in the engine compartment. (Use a shop cloth to absorb any fuel leakage while making the connection.)
b. Ignition "ON," observe the fuel pressure.
c. Is the fuel pressure within the specified values, and does it hold steady ?
[YES] Go to Step 6.
[NO] Go to Step 5.
5. Is any fuel pressure indicated?
[YES] Go to Fuel System Electrical Test. Fuel System Electrical Test
[NO] Go to Fuel System Diagnosis. Fuel System Diagnosis
6. a. Install the switch box J 39021-2 at the injector test connector and activate an injector.
b. Did the fuel pressure drop when the injector was activated?
[YES] Go to Step 7.
[NO] Go to Step 18.
7. a. Install an injector test light at the # 2 cylinder injector harness connector (or install J 39021-65 test light to the injector test connector).
b. Does the test light blink when the engine is cranked?
[YES] Go to Step 8.
[NO] Go to Step 24.
8. a. Ignition "OFF."
b. Disconnect the 6-pin connector at the ignition control module.
c. With a test light to B+, probe each of the 6 exposed ignition module pins, one at a time, while the engine is cranked. (Use the gray narrow METRI-PAK (c) flexible female connector from the J-3561 6 kit to make the pin accessible.)
d. Does the light flash at each pin when the engine is cranked?
[YES] Go to Step 12.
[NO] Go to Step 9.
9. Remove the 5-pin connector at the ignition module.
b. Ignition "ON."
c. Use a test light at the harness connector to verify that the module is being supplied with B+ and ground.
d. Was a problem found?
[YES] Go to Step 10.
[NO] Go to Step 11.
10. a. Repair the open ignition feed circuit or ground circuit to the ignition module.
b. Is the action complete?
[YES] Verify repair.
11. Repair the ignition module.
[YES] Verify repair.
12. a. Reconnect the ignition module 6 pin connector.
b. Remove the electrical connector from each coil.
c. With a test light to B+, probe each of the coil connectors at the wire which runs to the ignition module. (Wire color will match the wire color at the ignition module 6-pin connector - green, or green with a tracer.)
d. Does the light flash at each coil connector when the engine is cranked?
[YES] Go to Step 14.
[NO] Go to Step 13.
13. Check for an open circuit between the coil and ignition module.
b. Is the action complete?
[YES] Verify repair.
14. a. Ignition "ON."
b. While the coil connectors are disconnected, touch each coil connector's ignition feed terminal with a grounded test light (the ignition feed wire is black with orange tracer).
c. Did the test light illuminate?
[YES] Go to Step 16.
[NO] Go to Step 15.
15. a. Repair the open ignition feed circuit.
b. Is the action complete?
[YES] Verify repair.
16. a. While the coil connector are disconnected, touch each connector's secondary ground terminal with a test light to B+. (The ground wires are black).
d. Does the test lamp illuminate at each coil connector?
[YES] Go to Step 18.
[NO] Go to Step 17.
17. Repair the open secondary ground circuit.
b. Is the action complete?
[YES] Verify repair.
18. a. Test the fuel for contamination.
b. If a problem is found, clean the fuel system and correct the contaminated fuel condition as necessary.
c. Replace the Fuel Filter and replace any injectors that are not delivering fuel (see Injector Balance Test).
d. Was a problem found?
[YES] Verify repair.
[NO] Go to Step 19.
19. a. Remove any ignition coil and install a spark tester at the spark plug end of the coil.
b. Observe the tester while the engine is cranking. Was a crisp, blue spark observed? Only one or two sparks followed by no result is considered the same as "No Spark."
[YES] Go to Step 21.
[NO] Go to Step 20.
20. a. Replace the ignition coil, and return to Step 19 to test the remaining coils.
b. Is the action complete?
[YES] Verify repair.
21. a. Repeat Step 19 for each coil. Remove only one coil at a time, and reinstall each coil on its spark plug after testing, but do not refasten coils with screws at this time.
b. After all coils have passed the spark test, does the engine start?
[YES] Refasten all coils with their screws.
[NO] Go to Step 22.
22. a. Remove the spark plugs from all cylinders.
b. Visually inspect the spark plug electrodes.
c. Replace any spark plugs with loose or missing electrodes or cracked insulators.
d. Did your inspection reveal any spark plugs exhibiting excessive fouling?
[YES] Correct the fouling condition.
[NO] Go to Step 23.
23. a. Refer to Engine / System Diagnosis to diagnose the following conditions:
- Faulty or incorrect camshaft drive belt.
- Leaking or sticky valves or rings.
- Excessive valve deposits.
- Loose or worn rocker arms.
- Weak valve springs.
- Incorrect valve timing.
- Leaking head gasket.
b. Is the action complete?
[YES] Verify repair.
[NO] Go to Step 25.
24. a. Observe the "Engine Speed" data display on the scan tool while cranking the engine.
b. Is the engine RPM indicated? (If the scan tool is normally powered from the cigarette lighter socket, and if the scan tool display goes blank while cranking the engine, it will be necessary to power the scan tool directly from the vehicle batter
[YES] Go to Step 25.
[NO] Go to Step 34.
25. a. Disconnect the 7-pin gray connector at the rear of the air filter beneath the point where the air duct attaches to the MAF sensor.
b. Ignition "ON."
c. Using a test light connected to ground, probe the ignition terminal at the [1][2]PCM (female) side of the 7-pin connector.
d. Is the test light "ON?"
[YES] Go to Step 26.
[NO] Go to Step 32.
26. a. At the [1][2]PCM (female) side of the connector mentioned in step 25, connect a test light between the ignition + terminal and one of the injector driver circuits at the same connector.
b. Ignition "ON."
c. Observe the test light, and repeat the test for each injector driver circuit.
d. Did the test light stay on when checking any of the 6 injector driver circuits?
[YES] Go to Step 27.
[NO] Go to Step 29.
27. a. Ignition "OFF," disconnect the [1][2]PCM.
b. Ignition "ON," observe the test light.
c. Is the test light "ON?"
[YES] Go to Step 28.
[NO] Go to Step 33.
28. a. Locate and repair the short to ground in the injector driver circuit.
b. Is the action complete?
[YES] Verify repair.
29. a. Using the same test location as in step 26, connect a test light between the ignition terminal and one of the driver circuits.
b. Crank the engine and observe the test light.
c. Repeat for each injector driver circuit.
d. Did the light blink during the test for each circuit?
[YES] Go to Step 31.
[NO] Go to Step 30.
30. a. Check for an open injector driver circuit.
b. Was a problem found?
[YES] Verify repair.
[NO] Go to Step 33.
31. a. At the injector (male) side of the gray connector mentioned in step 25, connect an ohmmeter between the ignition pin and one of the driver circuit pins.
b. Check for continuity in the circuit.
c. Repeat for each injector circuit. The readings should be approximately equal to the specified value for injector resistance.
d. Was a problem found?
[VALUES] 12.5 ohms.
[YES] Verify repair.
[NO] Go to Step 8.
32. a. Repair the ignition feed circuit.
b. Is the action complete?
[YES] Verify repair.
33. a. Replace the [1][2]PCM.
IMPORTANT: The replacement [1][2]PCM must be programmed.
b. Is the action complete?
[YES] Verify repair.
34. a. Raise the vehicle and disconnect the CKP sensor harness.
b. Ignition "ON."
c. With a test light to ground, probe the harness ignition feed terminal.
d. Did the light illuminate?
[YES] Go to Step 36.
[NO] Go to Step 35.
35. a. Check the ignition feed wire between the sensor and the [1][2]PCM for a short to ground or open circuit.
b. Is the action complete?
[YES] Verify repair.
36. a. Ignition "ON."
b. At the CKP harness connector, connect a test light between the ignition and ground terminals.
c. Did the light illuminate?
[YES] Go to Step 38.
[NO] Go to Step 37.
37. a. Check the sensor ground circuit for an open or short to voltage.
b. Is the action complete?
[YES] Verify repair.
38. a. Check the signal circuit between the sensor and the [1][2]PCM for a short to ground, short to voltage, or an open.
b. Was a problem found?
[YES] Verify repair.
[NO] Go to Step 39.
39. a. Replace the CKP position sensor.
b. Is the action complete?
[YES] Verify repair.
[NO] Go to Step 33.