Here's what you should do:
1. Don't drive the car: Continuing to drive with this problem could cause further damage and create a safety hazard.
2. Take it to a qualified mechanic or auto electrician: This is the safest and most reliable way to get this issue resolved. A professional will be able to accurately diagnose the problem (whether it's a faulty switch, a short in the wiring harness, a damaged relay, or something else) and make the necessary repairs.
3. Explain the problem clearly: When you take your car in, describe exactly what happens – that turning on the headlights simultaneously activates the rear defroster, fan, and AC.
The mechanic will likely perform these steps (or similar ones):
* Visual Inspection: They'll visually inspect the wiring harness, looking for any obvious damage, fraying, or loose connections.
* Circuit Testing: They'll use a multimeter to check the electrical circuits and identify where the short circuit is occurring.
* Component Testing: They may test various components, such as switches, relays, and fuses, to determine if any are faulty.
* Repair or Replacement: Once the problem is identified, they'll repair or replace the faulty component(s).
In short, don't try to fix this yourself. A professional diagnosis and repair are essential to ensure your safety and the proper functioning of your vehicle's electrical system.
