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

Learn how to diagnose and fix P0700 transmission control system fault in GMC Sierra T1XX. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Ensure the vehicle is on a flat, stable surface and secure it with wheel chocks.

2. Inspect and Replace Transmission Fluid

• Tools Required: Transmission fluid pump, socket set, funnel.
• Remove the transmission pan bolts using a socket.
• Carefully lower the transmission pan and drain the fluid into a clean container.
• Inspect the fluid for debris or contaminants. If dirty, replace with new fluid.
• Clean the pan and replace the transmission filter if applicable.
• Reinstall the pan with a new gasket and torque the bolts to the manufacturer's specification (usually around 10-15 ft-lbs).

3. Repair or Replace TCM (if required)

• If the TCM is found to be faulty during testing:
  • Disconnect the wiring harness from the TCM.
  • Remove the mounting bolts securing the TCM and carefully take it out.
  • Install the new TCM by reversing the removal steps.
  • Reconnect the wiring harness ensuring all connections are secure.

4. Test Drive and Recheck

• Reconnect the negative battery terminal.
• Start the engine and let it idle for a few minutes.
• Take the vehicle for a test drive to confirm proper shifting and operation.
• Recheck for any new or previously stored error codes.