Starting Motor Fundamentals

SEAT BELT/STARTER INTERLOCK

By law, all late model cars are equipped with starter interlocks in conjunction with shoulder and lap belts. The starter interlock, prevents the engine from starting until all front seat passengers have been seated and buckled their belts.

TROUBLESHOOTING: STARTING SYSTEM

TROUBLE: STARTER CRANKS ENGINE SLOWLY

Possible Cause

1. Discharged battery or defective cell.

2. Excessive resistance in starter.

3. Excessive resistance in cranking circuit.

4. Engine oil too heavy for prevailing temperature.

5. Excessive engine friction.

Correction

1. Make specific gravity and load tests. Recharge or replace battery.

2. Disassemble and check for bent armature, or armature dragging on field poles. Straighten or replace armature.

3. Make voltmeter or ohmmeter checks at cable connections, solenoid or relay, and at ground connections. Repair or replace units as required.

4. Change oil to suit conditions.

5. Check the tight-fitting engine bearings, pristons, rings, etc.

TROUBLE: STARTER INOPERATIVE

Possible Cause

1. Loose or corroded battery terminals.

2. Discharged battery.

3. Dead battery.

4. Open starting circuit.

5. Inoperative solenoid or relay.

6. Faulty ignition switch.

7. Defective starter.

8. Inoperative neutral safety switch (cars with automatic transmission).

Correction

1. Clean battery posts and cable clamps. Tighten clamps securely.

2. Recharge battery.

3. Replace battery.

4. Check cable connections, ignition switch, solenoid or relay and writing. Repair as required.

5. Use heavy jumper cable to bypass unit. Replace faulty solenoid or relay.

6. Replace switch.

7. Disassemble starter and inspect parts. Repair or replace starter.

8. Check operation of switch. Adjust or replace switch.

TROUBLE: STARTER TURNS BUT DRIVE DOES NOT ENGAGE

Possible Cause

1. Broken teeth in fly wheel ring gear.

2. Rusted starter drive shaft.

3. Defective starter drive.

Correction

1. Replace ring gear.

2. Clean, lubricate shaft.

3. Replace drive unit.

TROUBLE: STARTER DOES NOT DISENGAGE

Possible Cause

1. Faulty ignition switch.

2. Short circuit in solenoid.

3. Stuck solenoid contact switch plunger spring.

4. Broken solenoid plunger spring.

5. Faulty starter relay.

Correction

1. Replace switch.

2. Replace solenoid.

3. Repair solenoid.

4. Replace spring or solenoid.

5. Replace relay.