how to fix GMC Sierra T1XX (2019-Present) power mirror not adjusting

GMC Sierra T1XX (2019-Present)

Error Codes

1-2 hours

Time

medium

Difficulty

medium

Severity

3 min read

558 words

Problem Statement

Learn how to diagnose and fix the power mirror adjustment issue in GMC Sierra T1XX (2019-Present). Step-by-step guide with tools and safety tips.

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 shock.
•Allow the vehicle to sit for a while if the engine has recently been running, to prevent burns from hot components.

Symptoms

•Power mirror does not respond to adjustment commands
•Mirror adjustment switch feels loose or unresponsive
•Other electrical components in the door may also be malfunctioning
•No sound or movement from the mirror when attempting to adjust
•Check engine light illuminated (if related electrical components are affected)

Diagnostic Steps

1
Inspect the mirror adjustment switch for physical damage or wear.
2
Use an OBD-II scanner to check for any related error codes that might indicate electrical problems.
3
Test the power supply to the mirror motor using a multimeter.
4
Check the wiring harness for any signs of damage or disconnections.
5
Inspect the fuse associated with the power mirror function to ensure it is intact.

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

•OBD-II scanner
•Multimeter
•Screwdriver set
•Trim removal tool
•Socket set
•Torque wrench

Parts Required

•Replacement mirror motor (if faulty)
•New door panel clips (if damaged during removal)

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Symptoms

•Power mirror does not respond to adjustment commands

•Mirror adjustment switch feels loose or unresponsive

•Other electrical components in the door may also be malfunctioning

•No sound or movement from the mirror when attempting to adjust

•Check engine light illuminated (if related electrical components are affected)

Diagnostic Steps

1
Inspect the mirror adjustment switch for physical damage or wear.
2
Use an OBD-II scanner to check for any related error codes that might indicate electrical problems.
3
Test the power supply to the mirror motor using a multimeter.
4
Check the wiring harness for any signs of damage or disconnections.
5
Inspect the fuse associated with the power mirror function to ensure it is intact.

Solution

1. Preparation

Gather tools and parts.
Ensure the vehicle is parked on a level surface with the ignition turned off.
Disconnect the negative battery terminal to avoid electrical shock.

2. Remove the Door Panel

Tools Required: Screwdriver set, trim removal tool.
Remove screws from the door panel as indicated in the vehicle's service manual.
Carefully use a trim removal tool to pry off the door panel without damaging clips.
Disconnect any electrical connectors for window switches and door lock.

3. Inspect and Test the Mirror Motor

Locate the mirror motor connector behind the door panel.
Tools Required: Multimeter.
Using a multimeter, test for voltage at the mirror motor connector while operating the adjustment switch.
If voltage is present but the mirror does not move, the mirror motor may need replacement.

4. Replace the Mirror Motor (if necessary)

Tools Required: Socket set, torque wrench.
Remove the screws or bolts securing the mirror assembly to the door.
Disconnect the electrical connector from the mirror motor.
Install the new mirror motor by reversing the removal steps and securing it with the appropriate torque specifications (usually around 10-15 ft-lbs).

5. Reassemble the Door Panel

Reconnect any electrical connectors.
Align the door panel and press it back onto the clips.
Replace all screws and secure the door panel firmly.

6. Final Checks

Reconnect the negative battery terminal.
Test the power mirror adjustment function to ensure it operates correctly.