Diagnosis and Testing

The starting system requires little maintenance. Simply, keep the battery fully charged and all electrical connections clean and tight.

Diagnosis of starting system problems is relatively easy. The system combines electrical and mechanical components. The cause of a starting problem may be electrical (e.g., faulty switch) or mechanical (e.g., wrong engine oil or a faulty flywheel ring gear).

Specific symptoms of starting system problems include:

• The engine will not crank;

• The engine cranks slowly;

• The starter keeps running;

• The starter spins, but the engine will not crank; and,

• The starter does not engage or disengage properly.

For each of these problems, refer to the chart below for the possible causes and needed actions. Diagnosis starts with a thorough visual inspection. Testing includes: a starter motor current draw test, starter circuit voltage drop tests, operational and continuity checks of control components, and starter motor bench tests.

SYMPTOM

POSSIBLE CAUSE

ACTION NEEDED

Engine will not crank

• Melted fusible link

• Loose connections

• Faulty ignition switch

• Faulty magnetic switch, relay, neutral start switch or clutch switch

• Mechanical problem in engine

• Problem in theft deterrent system

• Check battery state-of-charge

• Replace fusible link

• Clean and tighten connections

• Check switch operation; replace as needed

• Check and replace as needed

• Check service manual for system tests

Engine cranks too slowly to start

• Loose or corroded connections

• Faulty starter motor

• Mechanical problems with engine or starter

• Check battery and charge as needed

• Clean and tighten connections

• Check engine and starter; replace worn out parts

Starter keeps running

• Damaged pinion or ring gear

• Faulty plunger in magnetic switch

• Faulty ignition switch or control circuit

• Binding ignition key

• Check gears for wear or damage

• Test starter pull-in and hold-in coils

• Check switch and circuit components

• Check key for damage

Starter spins, but engine will not crank

• Faulty over-running clutch

• Damaged or worn pinion gear or ring gear

• Check over-running clutch for proper operation

• Check gears for damage and wear; replace as needed

Starter does not engage/disengage properly

• Faulty magnetic switch

• Damaged or worn pinion gear or ring gear

• Bench test starter

• Check gears for damage and wear; replace as needed

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

Don't pay hundreds of dollars to find out what is wrong with your car. This book is dedicated to helping the do it yourself home and independent technician understand and use OBD-II technology to diagnose and repair their own vehicles.

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