Car electrical diagnostics
Equipment required for diagnosis:
* Multimeter
* Light Emitting Diode (LED) or lamp
* Diagnostic probes
*Car wiring diagram (for reference)
Diagnostic stages:
1. Interview with the owner and inspection of the car
* Ask the owner questions about the malfunctions observed in the car.
* Check all components that could be causing the problem, such as battery, alternator, starter.
2. Visual inspection
* Visually inspect wiring harnesses, connectors and connections for damage or corrosion.
* Look for signs of overheating, such as melted insulation or discolored wires.
3. Checking battery voltage
* Connect the red lead of the multimeter to the positive terminal of the battery and the black lead to the negative terminal.
*Voltage should be between 12.6 and 13.2 volts with the engine off.
* Start the engine and check the voltage again. It should be between 13.8 and 14.5 volts.
*If the voltage deviates from these values, it may indicate a problem with the battery, alternator, or starter.
4. Check the charging system
* Start the engine and turn on as many electrical components as possible (headlights, heated rear window, etc.).
*Connect the red lead of the multimeter to the positive terminal of the alternator and the black lead to the negative terminal of the battery.
*Voltage should be between 13.8 and 14.5 volts.
*If the voltage is below this value, it may indicate a problem with the alternator or voltage regulator.
5. Checking the starting system
* Try to start the engine.
*Connect the red lead of the multimeter to the positive terminal of the starter and the black lead to the negative terminal of the battery.
*Voltage should drop to 9-11 volts during startup.
*If the voltage drops too much or does not drop at all, it may indicate a faulty starter, solenoid, or battery.
6. Wiring check
* You can use an LED or a lamp to check the wiring for an open or short circuit.
*Connect one wire from the LED or lamp to the positive terminal of the battery and the other to the wire being tested.
* If the LED lights up, the circuit is good.
*If the LED does not light up, this indicates an open circuit.
7. Diagnostics using a diagnostic scanner
* Connect the diagnostic scanner to the vehicle’s diagnostic port.
* The scanner reads fault codes from the vehicle’s on-board computer and provides information about faults.
8. Additional checks
*If the above checks do not reveal a problem, more in-depth diagnostics may need to be performed, such as:
* Relay test
* Checking fuses
* Checking ground connections
Note:
* When diagnosing electrical wiring, always follow safety precautions.
* Disconnect the negative terminal of the battery before starting work.
*Use insulated tools and wear protective gloves.