Set the gearbox to neutral position and turn on the ignition.
Using an auxiliary wire (with a cross-section of at least 4 mm), short-circuit terminals 30 and 50 of the starter.
If the starter works properly, then the problem lies in the wiring. If the starter does not work, it must be removed and checked.
When checking the connection, the wires must be well secured and not oxidized.
| Sign of malfunction | Possible reason | Method of elimination |
| The starter does not turn when the ignition is on | The battery is discharged | Charge the battery |
| Jumper terminals 30 and 50 of the starter: the starter rotates. Wire 50 in the ignition switch is broken, the ignition switch is defective | Fix the break, replace damaged parts | |
| Broken wire or ground connection | Check the wires and their connection to the battery | |
| The battery is discharged | Measure the battery voltage or charge it | |
| High transition resistance due to loosening and oxidation of connections | Clean the battery terminals. Secure the connection between the battery, starter and ground | |
| No voltage at terminal 50 (start relay) | Broken wire, defective ignition switch | |
| Starter relay failure (diesel engine) | Check or replace the relay | |
| Slow rotation of the starter, the starter does not turn the engine | The battery is discharged | Charge the battery |
| The wrong oil was poured into the engine | Fill with multi-grade oil | |
| High transition resistance due to weakening and oxidation of connections | Clean the battery and starter connection terminals, secure the contacts | |
| Brushes do not fit the collector, are stuck in the guides, are worn, broken or dirty | Check, clean or replace carbon brushes, check guides | |
| Small distance between brushes and commutator | Replace the carbon brushes and clean their guides | |
| The collector is scratched, burnt or dirty | Turn the commutator or replace the anchor | |
| No voltage at terminal 50 (less than 8 V) | Check the ignition switch or starter relay | |
| Starter relay defective | Replace the starting relay | |
| The starter engages but does not pull, the engine turns in jerks | Gearbox failure | Replace the gearbox |
| Gear contamination | Clean the gears | |
| Damage to the flywheel ring gear | Treat the ring gear, replace the flywheel | |
| The gear does not disengage from the flywheel | The gearbox or the helical splines of the armature shaft are dirty or damaged | Clean or replace the gearbox |
| Starter relay failure | Replace the starting relay | |
| The return spring is damaged | Replace the spring | |
| The starter operates after the ignition key is released | The starting relay is stuck | Turn off ignition immediately, replace starter relay |
| The ignition switch does not turn off | Disconnect the wires from the battery and replace the ignition switch |
[The article is reprinted from this source: MitsubishiMan]