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

Learn how to troubleshoot and fix P0700 transmission control malfunction in GMC Sierra T1XX. Step-by-step guide with diagnostic and repair instructions.

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to prevent any electrical shorts.
• Allow the vehicle to cool down if the engine has been running.

2. Inspect and Replace Transmission Fluid

• Sub-steps:
  • Locate the transmission dipstick and remove it.
  • Check the fluid level. If low, add the recommended transmission fluid (check the owner’s manual for specifications).
  • If the fluid is dirty or burnt, drain the transmission fluid using a catch pan.
  • Replace the filter if necessary, following the manufacturer's instructions.
  • Refill the transmission with the correct type and amount of fluid.

Tools Required:

• Catch pan
• Funnel
• Transmission fluid

3. Inspect Wiring and Connectors

• Sub-steps:
  • Visually inspect the wiring harness connected to the TCM for frays, breaks, or signs of wear.
  • Disconnect and reconnect wiring connectors to ensure a good connection.
  • Repair or replace any damaged wiring or connectors as needed.

Tools Required:

• Wire stripper/crimper
• Electrical tape

4. Test the Transmission Control Module

• Sub-steps:
  • Reconnect the battery.
  • Use a multimeter to check the voltage and ground at the TCM connector.
  • Compare the readings with the specifications in the service manual.
  • If readings are out of range, the TCM may need replacement.

Tools Required:

• Multimeter

5. Replace the Transmission Control Module (if necessary)

• Sub-steps:
  • Locate the TCM (usually under the dashboard or near the transmission).
  • Disconnect the TCM by removing the connector.
  • Unbolt the TCM from its mounting.
  • Install the new TCM by reversing the removal steps, ensuring all connections are secure.

Parts Required:

• Transmission Control Module (if replacement is needed)