how to diagnose P0700 transmission code in GMC Sierra T1XX (2019-Present)

• •Check engine light illuminated
• •Transmission malfunction indicator light active
• •Erratic shifting or harsh shifting
• •Delayed engagement when shifting from park to drive
• •Reduced fuel efficiency
• •Possible loss of power during acceleration

1. 1Scan the vehicle’s onboard diagnostic system using an OBD-II scanner to confirm the P0700 code and identify any additional transmission-related codes.
2. 2Inspect the transmission fluid level and condition; check for contamination or burnt odor.
3. 3Examine the wiring and connectors related to the transmission control module for damage or corrosion.
4. 4Verify the battery voltage and ground connections to ensure proper power supply to the TCM.
5. 5Test the TCM with a multimeter to check for proper voltage and ground signals.
6. 6If applicable, check for any TCM software updates or reprogramming requirements from the manufacturer.

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

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

• •OBD-II scanner
• •Multimeter
• •Socket set
• •Torque wrench
• •Electrical contact cleaner

• •Transmission fluid
• •Transmission control module (if replacement is necessary)
• •Wiring harness (if damaged)