Think a starter or alternator may be failing? Here's a quick checklist of things to keep in mind and inspect for, courtesy of Clint Stohler, director of training/tech support for Remy Power Products, a manufacturer of new and reman starters and alternators.
Starters
Engine won't start
- Defective fusible link
- Loose connections
- Defective ignition switch
- Defective solenoid/mag switch, relay, neutral start switch or clutch switch
- Could also be dead battery, mechanical problem in engine or problem in vehicle anti-theft system
Engine cranks too slow
- Loose or corroded connections
- Defective starter motor
- Could also be weak battery or mechanical problem with engine
Starter keeps running
- Damaged pinion or ring gear
- Defective starter or magnetic switch
- Defective ignition switch or control circuit
Starter spins but engine will not crank
- Defective drive clutch
- Defective starting motor
Alternators
No output, battery condition good, dashboard indicator light illuminates when key on engine off
- Drive belt broken or loose
- No voltage signal to field through regulator plug
- Voltage not present at alternator B+ terminal
- Defective alternator
Low voltage output from alternator
- Corroded or loose connections
- Drive belt slipping
- Belt tensioner weak
Lights dim at idle while all accessories are off
- Cables corroded
- Improper body ground
- Drive belt slipping or tensioner weak
- Improper engine rpm’s at idle
- Defective alternator
- Could also be weak or defective battery
About the Author
Gregg Wartgow
Gregg Wartgow is a freelancer who Fleet Maintenance has relied upon for many years, writing about virtually any trucking topic. He lives in Brodhead, Wisconsin.
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