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 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
| Condition | Possible Cause | Action |
|---|---|---|
| Motor not running (No operating sound of magnetic switch) | Clutch pedal is not depressed fully or clutch pedal position switch is maladjusted (M/T) | Depress clutch pedal or adjust clutch pedal position 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 of 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) (If battery and wiring are satisfactory, inspect starting motor) | Insufficient contact of magnetic switch main contacts | Replace magnetic switch . |
| Layer short-circuit of armature | Replace . | |
| Disconnected, burnt or worn commutator | 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 . | |
| Noise | Abnormally worn bush | Replace bush . |
| Worn pinion or worn teeth of ring gear | Replace pinion or flywheel . | |
| 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 . |
CRANKING SYSTEM SYMPTOM DIAGNOSIS CHART
Cranking System Test
| CAUTION | Each test must be performed within 3 - 5 seconds to avoid coil from burning. |
Pull-in Test
Connect battery to the magnetic switch as shown.
Check that plunger and pinion move outward.
If plunger and pinion don't move, replace the magnetic switch.
Note. Before testing, disconnect lead wire from terminal M (2).
Scheme 2
Hold-in Test
While connected as the figure with plunger out, disconnect negative lead from terminal "M".
Check that plunger and pinion remain out.
If plunger and pinion return inward, replace the magnetic switch.
Scheme 3
Plunger and Pinion Return Test
Disconnect negative lead from starting motor body.
Check that plunger and pinion return inward.
If plunger and pinion don't return, replace the magnetic switch.
Scheme 4
No-load Performance Test
Connect battery and ammeter to starter as shown.
Check that starter rotates smoothly and steadily with pinion moving out. Check that ammeter indicates specified current.
Specified current (No-load performance test)
90 A MAX. at 11 V
Scheme 5
Starting Motor Inspection
Reference: STARTING MOTOR DISMOUNTING AND REMOUNTING
Reference: STARTING MOTOR COMPONENTS
Pull-in coil open circuit test
Check for continuity across magnetic switch "S" terminal (1) and "M" terminal (2). If no continuity, coil is open and should be replaced.
Scheme 6
Hold-in coil open circuit test
Check for continuity across magnetic switch "S" terminal (1) and coil case. If no continuity, coil is open and should be replaced.
