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 and parts.
• Park the vehicle on a flat surface and engage the parking brake.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Transmission Fluid Check

• Tools Required: Dipstick tool or funnel, transmission fluid.
• Remove the transmission dipstick and check fluid level. If low:
  • Add the manufacturer-recommended transmission fluid until proper level is reached.
  • Check fluid condition; if it is dark or has a burnt smell, a fluid change is necessary.

3. Inspect Wiring and Connectors

• Tools Required: Multimeter, wire brush, dielectric grease.
• Visually inspect the wiring harness connected to the TCM for any damage or corrosion.
• Use a multimeter to check for continuity in the wires leading to the TCM.
• Clean connectors with a wire brush, apply dielectric grease, and reconnect.

4. Test Transmission Control Module

• Tools Required: OBD-II scanner, multimeter.
• Use an OBD-II scanner to monitor the live data from the TCM.
• Check for any abnormal readings or errors in the input/output data.
• If the TCM is faulty, replace it with a new module, following the manufacturer’s instructions for programming and installation.

5. Transmission Fluid Change (if needed)

• Tools Required: Socket set, drain pan, funnel, new transmission fluid.
• Drain the old transmission fluid from the transmission pan by removing the drain plug.
• Replace the transmission filter if applicable.
• Reinstall the drain plug and refill the transmission with new fluid through the dipstick tube.