Symptom Diagnosis

Symptom checks cannot be used properly unless problem occurs while vehicle is being tested. To reduce diagnostic time, ensure steps in appropriate BASIC DIAGNOSTIC PROCEDURES article and SELF-DIAGNOSTICS - EEC-V (GASOLINE) article were performed before diagnosing a symptom. Symptom checks are listed in order of probability, ease of accomplishment, and accessibility. Symptoms available for diagnosis are as follows:

• ROUGH OR ROLLING IDLE, STALLS, MISSES, HESITATION OR SURGE 
• HARD START/LONG CRANK OR ERRATIC START/CRANK 
• NO START/NORMAL CRANK 
• SLOW RETURN TO IDLE 
• FAST IDLE (DIESELS/RUNS ON) 
• LOW IDLE (STALLS ON DECELERATION) 
• BACKFIRES 
• LACK/LOSS OF POWER 
• SPARK KNOCK 
• POOR FUEL ECONOMY 
• EMISSIONS COMPLIANCE 
• WARNING INDICATOR LIGHTS 
• IMPROPER AUTOMATIC TRANSMISSION SHIFT 
• TACHOMETER INOPERATIVE 
• HIGH OIL CONSUMPTION 
• ELECTRIC COOLING FAN DOES NOT RUN AT LOW &/OR HIGH SPEED 
• ELECTRIC COOLING FAN ALWAYS ON 
• HYDRAULIC COOLING FAN DRIVE RUNS AT ONE SPEED 
• EXHAUST SMOKE 
• FUEL ODOR 
• ENGINE NOISE 
• CLIMATE CONTROL (LACK OF COOLING) 
• CLIMATE CONTROL (A/C ALWAYS ON) 
• A/C DOES NOT TURN OFF DURING WOT 
• SULFUR SMELL