how to fix GMC Sierra T1XX (2019-Present) fog lights not working

GMC Sierra T1XX (2019-Present)

Error Codes

1-2 hours

Time

medium

Difficulty

medium

Severity

3 min read

508 words

Problem Statement

Learn how to diagnose and fix fog lights not working on GMC Sierra T1XX (2019-Present). Step-by-step guide with symptoms, diagnostic steps, and repair instructions.

Affected Component

Electrical

Estimated Time

1-2 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems to prevent short circuits.
•Allow the fog light assembly to cool if they have been in use prior to inspection or replacement.

Symptoms

•Fog lights do not illuminate when activated
•No sound from the fog light relay when switched on
•Check engine light illuminated (if related to electrical issues)
•Other exterior lights functioning normally
•Possible dimming or flickering of dashboard lights

Diagnostic Steps

1
Inspect the fog light bulbs for any signs of damage or burnout.
2
Check the fog light fuses in the fuse box for continuity.
3
Use an OBD-II scanner to check for any stored error codes related to the fog lights.
4
Measure voltage at the fog light connector using a multimeter to ensure power supply.
5
Inspect the fog light relay for proper operation.
6
Verify the wiring harness for any signs of damage or corrosion.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•Socket set
•Multimeter
•OBD-II scanner
•Pliers

Parts Required

•Fog light bulbs
•Fog light fuse (if needed)
•Fog light relay (if needed)

Related Faults

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Diagnostic Steps

1
Inspect the fog light bulbs for any signs of damage or burnout.
2
Check the fog light fuses in the fuse box for continuity.
3
Use an OBD-II scanner to check for any stored error codes related to the fog lights.
4
Measure voltage at the fog light connector using a multimeter to ensure power supply.
5
Inspect the fog light relay for proper operation.
6
Verify the wiring harness for any signs of damage or corrosion.

Solution

1. Preparation

Gather tools and parts required for the repair.
Disconnect the negative terminal of the battery to ensure safety during repairs.

2. Replace Fog Light Bulbs

Locate the fog light housing behind the bumper.
Twist and remove the fog light assembly from the housing.
Disconnect the wiring harness from the fog light bulb.
Replace the old bulb with a new, compatible fog light bulb (check owner's manual for specifications).
Reconnect the wiring harness and secure the fog light assembly back in place.

3. Replace Fog Light Fuse

Locate the fuse box, which is usually under the dashboard or in the engine compartment.
Identify the fog light fuse using the diagram on the fuse box cover.
Remove the faulty fuse and replace it with a new fuse of the same amperage.
Ensure the fuse is seated properly in its slot.

4. Test the Fog Light Relay

Access the relay box, typically located in the engine compartment.
Remove the fog light relay and test it using a multimeter for continuity.
If faulty, replace it with a new relay.

5. Reconnect Battery

Reconnect the negative terminal of the battery after all repairs.
Ensure all connections are tight and secure.