DIY Guide: How to Check and Repair Turn Signal Light Malfunctions｜BLIAUTO Professional Lighting Tutorial

2. DIY Troubleshooting Steps

1. Check the Bulb (Most Common Issue)

Tools needed: Screwdriver, replacement bulb, gloves

Remove the front or rear signal lens cover;

Inspect the bulb for blackening, broken filaments, or discoloration;

Replace it with a bulb of the same specification to test;

Ensure it's properly secured to prevent water ingress or poor contact.

Tip: LED bulbs don’t burn out easily, but poor wiring or a failed driver can still cause malfunction.

2. Check the Turn Signal Relay (Critical for Blink Rate Issues)

Purpose of the relay: Controls the blinking rhythm and maintains the correct frequency.

Open the vehicle’s fuse or relay box (usually under the dashboard or in the engine bay);

Locate the relay labeled “Turn Signal” or “Flasher”;

Place a finger on it to feel for rhythmic clicks during blinking;

Replace with a backup relay to determine if it's faulty.

3. Check the Turn Signal Switch and Wiring

If bulbs and relays are functioning properly, the issue may lie in the turn signal switch or wiring.

Carefully remove the steering column cover (disconnect the negative battery terminal to avoid airbag issues);

Check if the stalk is loose, aged, or has worn contacts;

Use a multimeter to test wiring continuity;

If the switch is suspected faulty, replace it with an OEM or manufacturer-recommended part.

3. Advanced Diagnostics (For More Experienced Users)

Test the ground connection: Poor grounding is a common issue. Ensure the light socket and vehicle body are properly connected.

Use an OBD scanner: Some modern vehicles log lighting faults through the CAN bus system.

Check compatibility of aftermarket LEDs: Some LED bulbs require load resistors to prevent “hyper flashing.”

Consult your vehicle’s wiring diagram: Understanding the signal path helps locate short circuits or breaks more accurately.

4. Repair and Replacement Suggestions