how to diagnose P0700 code in BMW 3 Series E90/E91 (2005-2012)

Solution

1. Preparation

• Gather tools and safety equipment.
• Disconnect the vehicle's battery to ensure safety while working on electrical components.

Tools Required:

• OBD-II scanner
• Multimeter
• Socket set
• Torque wrench
• Screwdrivers

2. Inspect and Change Transmission Fluid

• Check Fluid Level: Locate the transmission dipstick and remove it. Wipe clean, reinsert, and check the fluid level.
• Change Fluid: If the fluid is low or dirty, drain the transmission fluid using a fluid pump. Replace it with the manufacturer-recommended fluid.
  • Torque Specifications: Follow specific torque specs for the drain/fill plugs as per the service manual.

3. Repair Wiring and Connectors

• Inspect Wiring: Look for any damaged or frayed wires leading to the TCM.
• Repair or Replace: If any wires are damaged, either repair them with electrical tape or replace the entire harness as needed.
• Check Connectors: Ensure that all connectors are securely attached and free of corrosion. Clean or replace connectors as necessary.

4. Test and Replace TCM (if necessary)

• Testing: Use a multimeter to check the power supply and ground to the TCM.
• Replace TCM: If the TCM is faulty, remove it by disconnecting the wiring harness and unscrewing it from its mounting location. Install the new TCM and reconnect the wiring harness.