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

Learn how to diagnose and fix P0700 transmission code on GMC Sierra T1XX (2019-Present). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather the necessary tools and parts.
• Disconnect the vehicle battery.
• Raise the vehicle securely on jack stands to access the transmission.

2. Check and Replace Transmission Fluid

• Tools Required: Transmission funnel, drain pan, socket set, torque wrench.
• Inspect the transmission fluid level. If low, add the appropriate type of transmission fluid as specified in the owner's manual.
• If the fluid is dirty or has a burnt smell, drain the old fluid and replace with new fluid:
  • Place a drain pan under the transmission pan.
  • Remove the transmission pan bolts using a socket set.
  • Allow fluid to drain completely, then clean the pan and filter.
  • Replace the transmission filter if necessary.
  • Reinstall the transmission pan and torque the bolts to manufacturer specifications.

3. Inspect and Repair Electrical Connections

• Tools Required: Multimeter, wire brush, electrical cleaner.
• Inspect the wiring harness connected to the transmission and the TCM:
  • Check for any damaged wires or corroded connections.
  • Clean any corrosion using an electrical cleaner and a wire brush.
  • Repair or replace damaged wiring as necessary.

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

• Tools Required: OBD-II scanner, multimeter, socket set.
• If no wiring issues are found, test the TCM:
  • Use a multimeter to check for proper voltage at the TCM connector.
  • If the TCM is not functioning properly, remove it by unscrewing the mounting bolts and disconnecting the harness.
  • Replace it with a new module that matches the original specifications.
  • Reinstall the new TCM and reconnect the harness.

5. Clear Codes and Test

• Tools Required: OBD-II scanner.
• Once repairs are completed, reconnect the battery.
• Use the OBD-II scanner to clear the P0700 code and any other codes present.
• Perform a road test to ensure the transmission operates smoothly.