Tools for diagnosing electrics in a car:
* Multimeter
* Oscilloscope (optional)
* Probe lamp (or LED test lamp)
*Car wiring diagram
Diagnostic procedures:
1. Visual inspection:
* Check for loose or damaged wires, connectors and fuses.
* Check the battery and terminals for corrosion or damage.
2. Fuse testing:
* Use a multimeter in continuity test mode to check the integrity of the fuses.
* Replace any blown fuses.
3. Voltage check:
*Use a multimeter to measure the voltage on the battery. At idle it should be around 12.6V.
* Check the voltage at various points on the circuit to ensure it is correct.
4. Current testing:
* Use the multimeter in current mode to check the current in the circuit.
*Compare readings with manufacturer’s directions.
5. Resistance testing:
* Use a multimeter in resistance mode to check the resistance in the circuit.
*Compare readings with manufacturer’s directions.
6. Grounding testing:
*Use a multimeter to check for proper grounding.
* Measure the resistance between the negative terminal of the battery and a metal part of the car frame.
7. Signal testing:
* Use an oscilloscope to test control signals (eg from the ECU), sensors and actuators.
* Compare the received signals with the reference ones.
Common car electrical faults:
*Blown fuses
* Short circuits
* Circuit breaks
* Faulty sensors and actuators
* Defective battery
*Wiring problems
Adviсe:
*Always disconnect the battery before starting diagnostics.
*Use the correct tools and follow safety precautions.
*Refer to the vehicle wiring diagram if necessary.
* If necessary, contact a qualified auto electrician.