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, i.e. 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.
- Condition of trouble
- Tightness of battery terminals (including ground cable connection on engine side) and starting motor terminals
- Discharge of battery
- Mounting of starting motor
CRANKING SYSTEM DIAGNOSTIC PROCEDURE CHART
| 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 . |
| Malfunction of clutch pedal position switch (M/T) | Adjust or replace . | |
| 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 . | |
| Faulty starting motor control relay | Engine and Emission Control System Relay Inspection . | |
| Faulty ECM and its circuit | Inspection of ECM and Its Circuits . | |
| 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 brush assembly . | |
| Burnt or abnormally worn end bush | Replace front housing . | |
| Burnt commutator | Replace armature . | |
| Layer short-circuit of armature | Replace . | |
| Crankshaft rotation obstructed | Repair . | |
| 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 front housing . |
| 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 . |