SYMPTOM DIAGNOSIS
Symptom checks cannot be used properly unless problem occurs while vehicle is being tested. To reduce diagnostic time, ensure steps in BASIC DIAGNOSTIC PROCEDURES article and appropriate SELF-DIAGNOSTICS article were performed before diagnosing a symptom. Select the symptom that most accurately describes the vehicle's driveability problem and then perform that test. If the test performed does not repair the problem, continue with the next test in sequence until the problem is found and repaired. Symptoms available for diagnosis are as follows
- «ENGINE DOES NOT START»(ref-63406-S16657219882001020500000)
- «HARD START»(ref-63406-S32232161732001020500000)
- «STARTS & STALLS»(ref-63406-S04024485012001020500000)
- «HESITATION/STUMBLE»(ref-63406-S15730225262001020500000)
- «SURGE»(ref-63406-S23174132222001020500000)
- «LACK OF POWER/SLUGGISH»(ref-63406-S06956272152001020500000)
- «SPARK KNOCK/DETONATION»(ref-63406-S42711730152001020500000)
- «CUTS OUT/MISSES»(ref-63406-S31716462972001020500000)
- «BACKFIRE»(ref-63406-S17937190412001020500000)
- «RUNS ROUGH/UNSTABLE, ERRATIC IDLE»(ref-63406-S14417101592001020500000)
- «POOR FUEL ECONOMY»(ref-63406-S21818409192001020500000)
INTERMITTENT PROBLEM DIAGNOSIS
Intermittent fault testing requires duplicating circuit or component failure to identify the problem. These procedures may lead to PCM setting a Diagnostic Trouble Code (DTC) which may help in diagnosis.
If problem vehicle does not produce DTC, monitor voltage or resistance values using a DVOM while attempting to reproduce conditions causing intermittent fault. A status change on DVOM indicates a fault has been located.
Use a DVOM to pinpoint faults. When monitoring voltage, ensure ignition switch is in ON position or engine is running. Ensure ignition switch is in OFF position or negative battery cable is disconnected when monitoring circuit resistance. Status changes on DVOM during test procedures indicate area of fault.