why does my GMC Sierra T1XX (2019-Present) have a rough shift between gears?

GMC Sierra T1XX (2019-Present)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

3 min read

545 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix rough shifting between gears in GMC Sierra T1XX (2019-Present). Step-by-step guide with diagnostic procedures and repair instructions.

Affected Component

Transmission

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect battery before working on electrical systems.
•Allow engine and transmission to cool before starting repairs.

Symptoms

•Harsh or jerky shifting during acceleration
•Delayed engagement when shifting from park to drive or reverse
•Unusual noises during gear changes (e.g., clunking or grinding)
•Fluctuating RPMs during shifts
•Transmission slipping or loss of power during shifts

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to identify any transmission-related fault codes.
2
Check the transmission fluid level and condition; ensure it is within the recommended range and free of contaminants.
3
Inspect the transmission mount for signs of wear or damage.
4
Examine the throttle position sensor (TPS) for proper operation and any fault codes.
5
Test the transmission control module (TCM) for updates or faults.
6
Perform a visual inspection of the shift linkage and cables for proper adjustment and wear.

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
•Transmission funnel
•Drain pan
•Socket set
•Multimeter
•Jack and jack stands
•Screwdriver

Parts Required

•Transmission fluid (specific type as per manufacturer)
•Transmission filter (if applicable)
•Throttle position sensor (if faulty)
•Transmission mount (if damaged)

Related Faults

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Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to identify any transmission-related fault codes.
2
Check the transmission fluid level and condition; ensure it is within the recommended range and free of contaminants.
3
Inspect the transmission mount for signs of wear or damage.
4
Examine the throttle position sensor (TPS) for proper operation and any fault codes.
5
Test the transmission control module (TCM) for updates or faults.
6
Perform a visual inspection of the shift linkage and cables for proper adjustment and wear.

Solution

1. Preparation

Park the vehicle on a level surface and set the parking brake.
Disconnect the battery to ensure electrical safety during repairs.

2. Check and Replace Transmission Fluid

Tools Required: Transmission funnel, drain pan, socket set.
Remove the transmission pan using a socket set, allowing fluid to drain into the pan.
Inspect the fluid condition; if it is dark or has a burnt smell, it should be replaced.
Clean the transmission pan and replace the filter if applicable.
Reinstall the pan with new transmission fluid, ensuring to torque bolts to the manufacturer’s specifications.

3. Inspect and Replace Throttle Position Sensor (if faulty)

Tools Required: Multimeter, socket set, screwdriver.
Disconnect the electrical connector from the TPS.
Use a multimeter to test the TPS for proper voltage output as per the specifications in the service manual.
If the TPS is faulty, remove it using a socket set and replace it with a new one, then reconnect the electrical connector.

4. Inspect and Replace Transmission Mount (if damaged)

Tools Required: Jack and jack stands, socket set.
Raise the vehicle using a jack and secure it with jack stands.
Inspect the transmission mount for cracks or deterioration.
If damaged, remove the old mount using a socket set and replace it with a new mount, tightening to the specified torque.