Tools:
* Multimeter
* Screwdriver
* Wrench
Checks:
Battery
* Check voltage: Connect the red lead of the multimeter to the positive terminal of the battery and the black lead to the negative terminal. The voltage should be around 12.6V when the engine is off and over 13.2V when the engine is running.
* Check the capacity: Use a load plug or battery tester to check the capacity of the battery. It must match the specified rated capacity.
* Inspect the physical condition: Check for corrosion on the terminals, cracks in the housing, and electrolyte leaks.
Generator
* Check terminal voltage: Start the engine and measure the voltage at the alternator terminals. It should be around 14.2 V.
*Check the diode bridge: Use the multimeter in diode test mode. Connect the red probe to the positive terminal and the black probe to the negative terminal. Diodes must allow current to pass in one direction (red arrow) and block it in the other (black stripe).
* Check the stator and rotor: This check requires removing the alternator from the vehicle. Use an ohmmeter to check the stator and rotor windings for opens or shorts.
Starter
* Check terminal voltage: Connect a multimeter to the starter terminals. When the ignition is turned on, the voltage should drop to about 10 V.
*Check Current: Use a current clamp to measure the current drawn by the starter. It must meet the specified specifications.
* Check the solenoid relay: Use a screwdriver to short-circuit the solenoid relay terminals. The starter should turn on.
Wiring
* Check continuity: Use the multimeter in continuity mode to check for opens or shorts in the wires.
* Check Resistance: Measure the resistance of the wires to ensure it is within specifications.
* Check the insulation: Use a megger to check the insulation resistance of the wires. It should be very high (usually more than 100 MΩ).
Other checks:
* Check fuses and relays: Inspect fuses and relays for burnt threads or rust. Replace damaged components.
* Check lighting: Check the functionality of all external and internal lighting fixtures.
* Check the warning lights: Make sure all the warning lights are working properly.
* Check the wipers and windshield wipers: Check the operation of the windshield wipers, windshield wipers and washer nozzles.