Diagnostic Notes

NOTE: For catalytic converter and feedback system to function properly, it is essential that vehicle is at operating temperature, (except when attempting to diagnose cold start or cold driveability problem).

VERIFY PROBLEM

- Define customer complaint and reproduce symptom.

EXTRACT AND CLEAR FAULT CODES

- Diagnose and repair any fault code related problems before proceeding with further diagnosis. (This step verifies Powertrain Control Module (PCM) and related systems are functioning properly.)

PERFORM VISUAL INSPECTION:

- PCM ground connections for location, and condition (clean and tight).
- Vacuum hoses for condition, leaks or restrictions.
- Throttle body mounting area and intake manifold sealing surfaces, for vacuum leaks.
- Ignition wires for location, condition and connections. (Look for cracking, arcing or carbon tracking.)
- Wiring for location, condition and connections. (Look for pinches, cuts, melted insulation or bare wires.)
- Wiring harness and vacuum hose routing.

PROCEED TO DIAGNOSIS BY SYMPTOM

NOTE: These charts contain possible causes of symptoms. Proceed in logical order, easiest to check or most likely cause first.