GMC Sierra T1XX (2019-Present) check engine light P0700 code how to diagnose

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

Solution

1. Preparation

• Gather necessary tools and parts, including an OBD-II scanner, multimeter, transmission fluid, and any replacement components as needed.
• Ensure the vehicle is parked on a level surface, and the engine is off before beginning work.

2. Transmission Fluid Inspection

• Tools Required: Transmission dipstick (if applicable), funnel.
• Remove the transmission dipstick and check the fluid level.
• Inspect fluid color and smell; it should be bright red and have a clean smell. If it is dark or smells burnt, a fluid change may be necessary.
• If low, add the recommended transmission fluid type as specified in the owner's manual.

3. Wiring and Connector Inspection

• Tools Required: Basic hand tools (socket set, screwdrivers).
• Visually inspect the wiring harness and connectors connected to the TCM and transmission for signs of damage, corrosion, or loose connections.
• If any issues are found, repair or replace the damaged wiring or connectors.

4. TCM and Solenoid Testing

• Tools Required: Multimeter.
• Disconnect the TCM and test each pin according to the specifications in the service manual.
• Test the transmission solenoids for resistance; compare readings against manufacturer specifications.
• Replace any faulty solenoids or TCM as necessary.

5. Code Clearing and Test Drive

• Reconnect all components and use the OBD-II scanner to clear the P0700 code.
• Conduct a test drive to verify normal transmission operation and check if the check engine light reappears.