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

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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the vehicle battery to avoid electrical shorts.
• Raise the vehicle and secure it on jack stands if necessary.

2. Check and Replace Transmission Fluid

• Sub-steps:
  • Remove the transmission fluid dipstick and check the fluid level.
  • If low or contaminated, drain the old transmission fluid using a fluid evacuation tool.
  • Replace with manufacturer-recommended transmission fluid (e.g., GM Dexron VI).
  • Recheck fluid level and ensure it is within the proper range.

3. Inspect and Repair Wiring and Connectors

• Sub-steps:
  • Visually inspect the wiring harness and connectors leading to the TCM for any signs of wear or damage.
  • Repair any frayed wires or corroded connectors using appropriate electrical connectors.
  • Use dielectric grease on connectors to prevent moisture intrusion.

4. Test and Replace Transmission Control Module (if necessary)

• Sub-steps:
  • Use a scan tool to check for software updates for the TCM.
  • If updates are available, follow the manufacturer’s instructions to reprogram the TCM.
  • If the TCM is faulty, remove it by disconnecting the wiring harness and unbolting it from its mount.
  • Install the new TCM and reconnect the wiring harness.

5. Inspect and Replace Transmission Solenoids (if necessary)

• Sub-steps:
  • Locate the transmission solenoids (refer to service manual for exact location).
  • Remove the transmission pan if necessary to access solenoids.
  • Disconnect the solenoid wiring and remove the solenoid from its housing.
  • Install the new solenoid and reassemble any components removed.