how to troubleshoot GMC Sierra T1XX (2019-Present) transmission slipping

GMC Sierra T1XX (2019-Present)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

4 min read

609 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 troubleshoot and fix transmission slipping in GMC Sierra T1XX (2019-Present). Step-by-step guide with diagnostic steps and repair instructions.

Affected Component

Transmission

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical components.
•Allow the engine to cool before working on the transmission.

Symptoms

•Engine revs without acceleration
•Delayed or harsh shifting between gears
•Transmission fluid leaks under the vehicle
•Check engine light illuminated
•Increased engine RPMs without corresponding vehicle speed

Diagnostic Steps

1
Scan the vehicle's computer using an OBD-II scanner to identify any error codes related to the transmission.
2
Check transmission fluid level and condition using the dipstick; look for signs of contamination or burning.
3
Inspect the transmission wiring harness and connectors for damage or corrosion.
4
Test the transmission solenoids using a multimeter to ensure they are functioning correctly.
5
Verify that the transmission fluid is at the correct temperature using a scan tool and check for proper pressure readings.
6
Check for any software updates or recalls specific to the transmission control module.

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
•Socket set
•Torque wrench
•Funnel
•Clean rags
•Jack stands

Parts Required

•Transmission fluid
•Transmission filter (if applicable)
•Transmission solenoids (if applicable)
•Gasket for transmission pan

Related Faults

Share this solution

Comments

No comments yet

Be the first to share your thoughts

Back to Generation

Diagnostic Steps

1
Scan the vehicle's computer using an OBD-II scanner to identify any error codes related to the transmission.
2
Check transmission fluid level and condition using the dipstick; look for signs of contamination or burning.
3
Inspect the transmission wiring harness and connectors for damage or corrosion.
4
Test the transmission solenoids using a multimeter to ensure they are functioning correctly.
5
Verify that the transmission fluid is at the correct temperature using a scan tool and check for proper pressure readings.
6
Check for any software updates or recalls specific to the transmission control module.

Solution

1. Preparation

Gather necessary tools: OBD-II scanner, multimeter, socket set, torque wrench, transmission fluid, funnel, and clean rags.
Ensure the vehicle is parked on a level surface and the engine is turned off.

2. Fluid Inspection and Replacement

Check Fluid Level:
1. Start the engine and let it reach operating temperature.
2. With the transmission in park, pull the dipstick and wipe it clean.
3. Reinsert the dipstick and remove it to check the fluid level; add fluid if necessary.
Change Transmission Fluid:
1. Raise the vehicle using jack stands.
2. Place a drain pan under the transmission oil pan.
3. Remove the transmission pan bolts using a socket set, and carefully lower the pan to drain the old fluid.
4. Replace the transmission filter if applicable, following manufacturer specifications.
5. Clean the pan and magnet, if present, to remove any debris.
6. Reinstall the pan with a new gasket and torque the bolts to the manufacturer's specifications.
7. Refill the transmission with new fluid through the dipstick tube using a funnel.

3. Solenoid Testing and Replacement

Test Solenoids:
1. Disconnect the transmission solenoid connectors.
2. Use a multimeter to measure the resistance across the solenoid terminals; compare to manufacturer specifications.
Replace Solenoids (if necessary):
1. If solenoids are faulty, remove the transmission pan again (if not already done).
2. Locate and remove the faulty solenoid using a socket set.
3. Install the new solenoid, ensuring it is securely fastened.
4. Reinstall the transmission pan and refill with fluid.

4. Final Checks

After all repairs, check for leaks and ensure the fluid is at the correct level.
Perform a test drive to ensure proper operation of the transmission.