Possible causes of electrical failure in a car:
1. Discharged or faulty battery
* Check the battery voltage using a multimeter. It should be around 12.6 volts with the engine off.
* Check that the battery terminals are clean and secure.
2. Defective starter
* Try starting the engine using jumper cables. If the engine starts, the starter may be faulty.
* Check the starter terminals and connections for corrosion or looseness.
3. Faulty generator
* Check the generator voltage with the engine running. It should be about 14 volts.
* Check the alternator drive belt for tension and damage.
4. Short circuit or blown fuses
* Check the fuses located in the fuse box under the instrument panel.
* Replace blown fuses with fuses of the same rating.
5. Broken wiring or poor contact
* Check the wiring under the hood and inside the vehicle for damage or loose connections.
* Try moving or tapping the wires to identify possible contact problems.
6. Faulty ignition switch
* Try replacing the ignition switch with a known good one.
* Check the connections of the connectors and contacts of the switch.
7. Electronic control unit (ECU) failure
*A faulty ECU can lead to various electrical problems.
* Diagnosis of ECU malfunction requires specialized equipment and software.
8. Electrical interference
* Sources of electrical noise, such as radios or faulty electronic equipment, can interfere with the vehicle’s electrical system.
* Remove or disconnect possible sources of interference.
9. Humidity or corrosion
*Moisture or corrosion may affect electrical connections.
* Clean terminals, connectors and wiring from corrosion.
10. Other reasons
* Faulty sensors or switches
* Problems with the lighting system
* Errors in wiring or installation of electrical equipment