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

Learn how to diagnose and fix P0700 transmission fault 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, and torque wrench.
• Disconnect the battery to ensure safety.
• Allow the vehicle to cool down before beginning work.

2. Check Transmission Fluid

• Tools Required: Transmission dipstick or funnel for refilling.
• Remove the dipstick and check the fluid level; add the appropriate transmission fluid if low.
• Inspect fluid quality; if it is dirty or burnt, a fluid change is necessary.

3. Inspect Wiring and Connectors

• Visually inspect the wiring harness and connectors leading to the TCM.
• Look for frayed wires, corrosion, or loose connections.
• Repair or replace any damaged wiring or connectors.

4. Test Transmission Control Module

• Tools Required: Multimeter.
• Disconnect the TCM connector and check for voltage supply and ground continuity as per the service manual specifications.
• If the TCM is receiving insufficient power or ground, trace the circuit and repair as necessary.

5. Replace Transmission Fluid and Filter (if necessary)

• Tools Required: Socket set, replacement filter, and new transmission fluid.
• Drain the old transmission fluid by removing the pan; replace the filter if applicable.
• Reinstall the pan with new gasket material and torque to manufacturer specifications.
• Refill the transmission with new fluid as per manufacturer recommendations.