Engine Controls - Basic Diagnostic Procedures: Diagnosis Pontiac Aztek I

VISUAL INSPECTION

Visually inspect all electrical wiring. Look for chafed, stretched, cut or pinched wiring. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and not pinched or cut. If necessary, see VACUUM DIAGRAMS - AZTEK & RENDEZVOUS article to verify routing and connections. Inspect air induction system for possible vacuum leaks.

Diagnosis

1. Start engine and allow it to reach normal operating temperature. Increase engine speed to 2000-2500 RPM and note gauge. If reading exceeds 1.25 psi (.09 kg/cm 2 ), exhaust system is restricted.
2. Check exhaust system for collapsed pipe, heat distress and possible internal muffler failure. If none of these conditions exist, check for restricted catalytic converter. Replace as necessary.

NO-START DIAGNOSIS

Note. For terminal and circuit identification, see WIRING DIAGRAMS

1. Definition - No-start is defined as engine cranks properly, but does not start. Engine may fire a few times.

Circuit Description

The Ignition Control (IC) module has independent power and ground circuits. The circuits between the IC module and the PCM consist of the IC timing signal, IC timing control, low resolution engine speed signal and a low reference signal.

The IC module sends 3X signals to the PCM. The IC module controls the timing advance during engine cranking. The timing advance changes to PCM control after the PCM receives the second 3X signal and after the PCM applies 5 volts to the IC timing signal circuit.

Diagnostic Aids

An arcing spark plug wire or an arcing ignition coil to the IC module may cause a stall, misfire or a no-start condition.

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-155075-S24848794192003060600000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.4L AZTEK & RENDEZVOUS article. After performing diagnostic system check, go to next step.
2. Attempt to start the engine. Does engine start and run? If yes, go to next step. If no, go to step 4.
3. Disconnect the Crankshaft Position Sensor (CKP) sensor "B" connector from the Ignition Control Module (ICM). ICM control module is located on top of rear valve cover. CKP sensor "B" is located on right side of engine block. (Схема №3) Measure the resistance from the CKP sensor 1 signal circuit to the low reference circuit of the CKP sensor "B" with a DVOM. (Схема №1) Is the resistance within 800-1200 ohms? If yes, go to next step. If no, go to step 28.
4. Disconnect the CKP sensor "A". CKP sensor "A" is located on front of engine, near crankshaft pulley. (Схема №2) Observe the 3X crank sensor parameter with a scan tool. Crank the engine. Does the scan tool indicate a 3X crank sensor signal present? If yes, go to next step. If no, go to step 11.
5. Reconnect the CKP sensor "A". Test for spark at each cylinder with a Spark Tester (J-26792). Did you observe any non-sparking cylinders? If yes, go to next step. If no, go to step 9.
6. Inspect and test the affected cylinder spark plug wires, ignition coils and spark plugs for a short to ground or an arching to ground. If carbon tracking or corrosion is present, replace both components that are affected. Did you find and correct the condition? If yes, go to step 32. If no, go to next step.
7. Test the resistance of the spark plug wires. Is resistance more than 3000 ohms per foot? If yes, go to step 30. If no, go to next step.
8. Measure the secondary resistance of the ignition coils. Is the resistance 5000-8000 ohms? If yes, go to step 25. If no, go to step 29.
9. Inspect the spark plug wires for proper routing and for the correct firing order. If any spark plug wires are found to be misrouted, reroute as necessary. Did you find and correct the condition? If yes, go to step 32. If no, go to next step.
10. Remove spark plugs. Inspect spark plugs. Did you find the problem? If yes, go to step 31. If no, see «DIAGNOSTIC AIDS»(ref-152619-S31117751302003021700000).
11. Connect the CKP sensor "A". Disconnect the IC module. Turn ignition on. Connect a test light between the IC module ignition 1 voltage circuit and a good ground. (Схема №1) Does the test light illuminate? If yes, go to next step. If no, go to step 24.
12. Connect a test light between the IC module ignition 1 voltage circuit and the IC module ground circuit. Does the test light illuminate? If yes, go to next step. If no, go to step 26.
13. Test for an intermittent and for a poor connection at the ICM. Did you find and correct the condition? If yes, go to step 32. If no, go to next step.
14. Disconnect the CKP sensor "B" connector from the ICM. Probe the CKP sensor 1 signal circuit of the CKP sensor "B" with a test light connected to battery voltage. Does the test light illuminate? If yes, go to step 17. If no, go to next step.
15. Probe the CKP sensor 1 signal circuit of the CKP sensor "B" with a test light connected to a good ground. Does the test light illuminate? If yes, go to step 18. If no, go to next step.
16. Ensure the battery voltage is within specifications. Measure the voltage from the CKP sensor 1 signal circuit and the low reference circuit of the CKP sensor "B" with DVOM at the ICM harness connector. Crank the engine while observing the AC scale. Is the voltage greater than 200 mV? If yes, go to step 27. If no, go to step 19.
17. Test the CKP sensor 1 signal circuit for a short to ground. Did you find and correct the condition? If yes, go to step 32. If no, go to step 20.
18. Test the CKP sensor 1 signal circuit for a short to ground. Did you find and correct the condition? If yes, go to step 32. If no, go to step 20.
19. Test the CKP sensor "B" circuits for an open or CKP sensor 1 signal and low reference circuit shorted together. Did you find and correct the condition? If yes, go to step 32. If no, go to next step.
20. Test for an intermittent and for a poor connection at the ICM. Did you find and correct the condition? If yes, go to step 32. If no, go to next step.
21. Test for an intermittent and for a poor connection at the CKP sensor. Did you find and correct the condition? If yes, go to step 32. If no, go to next step.
22. Remove CKP sensor. Visually inspect the CKP sensor for physical damage, excessive play or looseness, improper installation, foreign material passing between the CKP sensor and reluctor wheel or wiring routed too closely to secondary ignition components. Did you find and correct the condition? If yes, go to step 32. If no, go to next step.
23. Visually inspect the reluctor wheel for foreign material passing between the CKP sensor and reluctor wheel, physical damage, excessive end play or looseness, improper installation, or excessive air gap between CKP sensor and reluctor wheel. Did you find and correct the condition? If yes, go to step 32. If no, go to step 28.
24. Repair the open or the short to ground in the IC module ignition 1 voltage circuit. Replace fuse, if necessary. After repairs, go to step 32.
25. Remove the coils associated with the cylinder that did not have spark. Connect a test light across the ignition module primary circuit, between the ICM terminals for the coils. Observe the test light while cranking the engine. Does the test light flash continuously while the engine is being cranked? If yes, go to step 29. If no, go to step 27.
26. Repair open in the IC module ground circuit. After repairs, go to step 32.
27. Replace IC module. After replacing module, go to step 32.
28. Replace CKP sensor "B". After replacing sensor, go to step 32.
29. Replace affected ignition coil(s). After replacing ignition coil(s), go to step 32.
30. Replace spark plug wires. After replacing spark plug wires, go to step 32.
31. Replace spark plugs. After replacing spark plugs, go to next step.
32. Turn ignition off for 30 seconds. Start engine and operate vehicle. Observe the MIL, vehicle performance and driveability. Does the vehicle operate normally, with no MIL? If yes, system is okay. If no, go to step 2.