how to diagnose Volkswagen Golf MK7 (2015-2019) electrical problems

Solution

1. Preparation

• Gather the necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical systems.
• Ensure the vehicle is parked on a level surface and secure it with wheel chocks.

2. Battery and Charging System Inspection

• Tools Required: Multimeter, battery tester
• Sub-steps:
  1. Remove the battery cover and disconnect the negative terminal first, followed by the positive terminal.
  2. Use the multimeter to measure the battery voltage (should be around 12.6 volts when fully charged).
  3. If voltage is low, charge the battery or replace it if it fails a load test.
  4. Inspect the alternator by measuring voltage at the battery while the engine is running (should be between 13.7 to 14.7 volts).

3. Fuse and Relay Inspection

• Tools Required: Fuse puller or needle-nose pliers
• Sub-steps:
  1. Locate the fuse box (usually under the dashboard or in the engine compartment).
  2. Remove fuses one at a time and inspect for any breaks or discoloration.
  3. Replace any blown fuses with the correct amperage rating as specified in the owner's manual.
  4. Check relays by swapping with a known good relay of the same type to see if the issue resolves.

4. Wiring Inspection

• Tools Required: Visual inspection tools, multimeter
• Sub-steps:
  1. Inspect visible wiring harnesses for signs of wear, fraying, or corrosion.
  2. Use a multimeter to check for continuity in suspect wires.
  3. Repair or replace damaged wiring as necessary, ensuring proper insulation and connection.

5. Component Testing

• Tools Required: Multimeter, specific tools for component removal
• Sub-steps:
  1. Test individual components such as switches, motors (e.g., window motors), and sensors.
  2. Disconnect the component, and measure resistance or voltage as specified in the service manual.
  3. Replace any components that do not meet specified measurements.