Cranking System Symptom Diagnosis

Possible symptoms due to starting system trouble would be as follows:

• Starting motor does not run (or runs slowly)
• Starting motor runs but fails to crank engine
• Abnormal noise is heard

Proper diagnosis must be made to determine exactly where the cause of each trouble lies.....in battery, wiring harness, (including starting motor switch), starting motor or engine.

Do not remove motor just because starting motor does not run. Check the following items and narrow down scope of possible causes.

1. Condition of trouble
2. Tightness of battery terminals (including ground cable connection on engine side) and starting motor terminals
3. Discharge of battery
4. Mounting of starting motor
   CRANKING SYSTEM SYMPTOM DIAGNOSIS
   
   

   Condition	Possible Cause	Action
   Motor not running - No operating sound of magnetic switch	Shift lever switch is not in P or N, or not adjusted (A/T)	Shift in P or N, or adjust switch  .
   	Battery run down	Recharge battery  .
   	Battery voltage too low due to battery deterioration	Replace battery  .
   	Poor contact in battery terminal connection	Retighten or replace  .
   	Loose grounding cable connection	Retighten  .
   	Fuse set loose or blown off	Tighten or replace  .
   	Poor contacting action of ignition switch and magnetic switch	Replace  .
   	Lead wire coupler loose in place	Retighten  .
   	Open-circuit between ignition switch and magnetic switch	Repair  .
   	Open-circuit in pull-in coil	Replace magnetic switch  .
   	Brushes are seating poorly or worn down	Repair or replace  .
   	Poor sliding or plunger and/or pinion	Repair  .
   Motor not running - Operating sound of magnetic switch heard	Battery run down	Recharge battery  .
   	Battery voltage too low due to battery deterioration	Replace battery  .
   	Loose battery cable connections	Retighten  .
   	Burnt main contact point, or poor contacting action of magnetic switch	Replace magnetic switch  .
   	Brushes are seating poorly or worn down	Repair or replace  .
   	Weakened brush spring	Replace  .
   	Burnt commutator	Replace armature  .
   	Layer short-circuit of armature	Replace  .
   	Crankshaft rotation obstructed	Repair  .
   Starting motor running, but too slow (small torque) - Battery and wiring are satisfactory	Insufficient contact of magnetic switch main contacts	Replace magnetic switch  .
   	Layer short-circuit of armature	Replace  .
   	Disconnected, burnt or worn commutator	Repair commutator or replace armature  .
   	Worn brushes	Replace brush  .
   	Weakened brush springs	Replace spring  .
   	Burnt or abnormally worn end bush	Replace bush  .
   Starting motor running, but not cranking engine	Worn pinion tip	Replace over-running clutch  .
   	Poor sliding of over-running clutch	Repair  .
   	Over-running clutch slipping	Replace over-running clutch  .
   	Worn teeth of ring gear	Replace flywheel (M/T) or drive plate (A/T)  .
   Noise	Abnormally worn bush	Replace bush  .
   	Worn pinion or worn teeth of ring gear	Replace over-running clutch, flywheel (M/T) or drive plate (A/T)  .
   	Poor sliding of pinion (failure in return movement)	Repair or replace  .
   	Worn internal or planetary gear teeth	Replace  .
   	Lack of oil in each part	Lubricate
   Starting motor does not stop running	Fused contact points of magnetic switch	Replace magnetic switch  .
   	Short-circuit between turns of magnetic switch coil (layer short-circuit)	Replace magnetic switch  .
   	Failure of returning action in ignition switch	Replace  .