how to fix the transmission code P0700 on my BMW 3 Series E90/E91 (2005-2012)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, fluid pump, transmission fluid.
• Ensure the vehicle is on a level surface and the engine is turned off before beginning any work.

2. Fluid Inspection and Replacement

1. Check Fluid Level:
   • Remove the transmission dipstick (if applicable) or the fill plug.
   • Check the fluid level; it should be within the specified range.
2. Inspect Fluid Condition:
   • If the fluid appears dark or has a burnt smell, it should be replaced.
3. Drain Old Fluid:
   • Place a drain pan under the transmission pan.
   • Remove the transmission pan bolts and carefully lower the pan to drain the fluid.
4. Replace with New Fluid:
   • Clean the transmission pan and replace the filter (if applicable).
   • Reinstall the pan and torque the bolts to manufacturer specifications.
   • Use a fluid pump to refill the transmission with the recommended fluid type, ensuring the level is correct.

3. Electrical Inspection

1. Inspect Wiring and Connectors:
   • Visual inspection of all wiring connected to the TCM and transmission for frays, breaks, or corrosion.
   • Repair or replace any damaged wiring or connectors.
2. Test TCM Functionality:
   • Using a multimeter, check for proper voltage and ground at the TCM.
   • If faulty, consider replacement of the TCM.

4. Solenoid Testing

1. Remove Transmission Solenoids:
   • Disconnect the electrical connectors and remove the solenoids as per manufacturer guidelines.
2. Test Solenoids:
   • Using a multimeter, check the resistance of each solenoid; refer to the service manual for specifications.
   • Replace any solenoids that do not meet specifications.