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 appropriate VACUUM DIAGRAMS article to verify routing and connections. Inspect air induction system for possible vacuum leaks.
Diagnosis
- 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, exhaust system is restricted.
- 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 .
- Definition - No-start is defined as engine cranks properly, but does not start. Engine may fire a few times.
Circuit Description
The electronic ignition system uses an individual ignition coil for each cylinder. The PCM controls ignition operation through 8 individual Ignition Control (IC) circuits. Each bank of 4 ignition coils is connected to PCM, power or ground by low reference, chassis ground, ignition 1 voltage circuits and appropriate IC circuit. PCM triggers an ignition coil by grounding appropriate IC circuit using information from Crankshaft Position (CKP) and Camshaft Position (CMP) sensors. The CMP sensor is located on top center rear of engine and CKP sensor is located on engine block, near starter. (Схема №1)or (Схема №2).
Diagnostic Aids
A missing CMP sensor signal may cause a long crank condition. The CKP signal must be available for engine to start. The CMP signal is not needed to start and operate engine. The PCM can determine when a cylinder is on either firing or exhaust stroke by 24X signal. Remove any debris from PCM connector surfaces before servicing PCM. Inspect PCM connector gaskets when diagnosing or replacing PCM. Ensure that gaskets are installed correctly. The gaskets prevent water intrusion into PCM.