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

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

Solution

1. Preparation

• Gather necessary tools: OBD-II scanner, multimeter, socket set, torque wrench, and transmission fluid.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent any electrical shorts.

2. Inspect and Replace Transmission Fluid

• Inspect Fluid: Remove the transmission dipstick and check the fluid level and condition.
• Replace Fluid (if needed):
  1. Place a drain pan under the transmission pan.
  2. Remove the transmission pan bolts with a socket set.
  3. Carefully lower the pan to avoid spilling fluid.
  4. Inspect the old fluid; if it is dark or smells burnt, a complete fluid change is necessary.
  5. Clean the transmission pan and replace the filter if applicable.
  6. Reattach the pan with new gasket and torque bolts to manufacturer specifications (typically 10-15 ft-lbs).
  7. Refill transmission with the correct type of fluid per manufacturer specifications.

3. Repair or Replace TCM

• If the TCM is found faulty:
  1. Disconnect the wiring harness from the TCM.
  2. Remove the TCM mounting bolts and carefully take out the module.
  3. Install the new TCM in the reverse order of removal.
  4. Reconnect the wiring harness securely.
  5. Reconnect the battery.

4. Clear Codes and Test Drive

• Use the OBD-II scanner to clear the P0700 code and any other related codes.
• Conduct a test drive to ensure proper transmission operation and monitor for any reoccurrence of DTCs.