my Toyota Highlander Fourth Generation (2020-present) headlights keep flickering what could be the i...

Solution

1. Preparation

• Gather tools and safety gear: gloves, safety glasses, and a multimeter.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Headlight Bulbs

• Sub-steps:
  1. Remove the headlight assembly as per the vehicle manual.
  2. Disconnect the electrical connector from the bulb.
  3. Remove the old bulb and inspect the base for corrosion.
  4. Install a new bulb, ensuring it is seated properly.
  5. Reconnect the electrical connector and reassemble the headlight assembly.

3. Check and Repair Wiring

• Sub-steps:
  1. Visually inspect the wiring harness for any signs of wear, fraying, or loose connections.
  2. Use a multimeter to check for continuity in the wiring.
  3. Repair any damaged wires using appropriate connectors and electrical tape.

4. Test Battery and Alternator

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use a multimeter to measure the battery voltage; it should read around 12.6 volts when off and 13.7-14.7 volts when running.
  3. If the voltage is low, consider testing or replacing the battery.
  4. Check the alternator output at different RPMs to ensure consistent voltage.

5. Inspect and Replace Headlight Relay

• Sub-steps:
  1. Locate the headlight relay in the fuse box as per the owner's manual.
  2. Remove the relay and inspect for signs of damage.
  3. Replace with a new relay if necessary.