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

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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.

2. Check and Replace Transmission Fluid

• Tools Required: Transmission fluid funnel, fluid pump, appropriate transmission fluid.
• Sub-steps:
  1. Locate the transmission dipstick or fill port.
  2. Remove the dipstick/fill cap and check the fluid level; add fluid if needed.
  3. If fluid is dark or smells burnt, drain and replace it.
  4. Use a fluid pump to fill new transmission fluid through the fill port until the correct level is reached.

3. Inspect and Repair Wiring

• Tools Required: Multimeter, wire brush, electrical cleaner.
• Sub-steps:
  1. Inspect the wiring harness for any visible damage.
  2. Use a multimeter to check for continuity in the wires leading to the TCM.
  3. Clean any corrosion found on connectors with electrical cleaner.
  4. Repair or replace any damaged wiring or connectors.

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

• Tools Required: OBD-II scanner, socket set.
• Sub-steps:
  1. If the TCM is suspected to be faulty, disconnect it from the wiring harness.
  2. Remove the TCM from its mounting bracket using a socket set.
  3. Install the new TCM by reversing the removal steps and reconnecting the wiring harness.
  4. Reconnect the battery and clear any diagnostic codes.

5. Final Checks

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the battery and start the engine.
  2. Use the OBD-II scanner to check for any remaining codes after repairs.
  3. Conduct a test drive to ensure smooth shifting and monitor for any reoccurrence of the P0700 code.