Fuel tank flap lock

Pin Color Function
1 GY/VT Connected to pin 71 of C2 connector in the BCM
2 WH/VT Connected to pin 62 of C2 connector in the BCM

Power supply to the relays is done directly over Kl.30, located in the engine bay and protected with fuse F17 (60 amps fuse). However, both electric lines going to the fuel tank flap lock motor have their own fuses. These are located in the BCM. F8 fuse provide protection for the UNLOCK line (WH/VT), while F12 fuse protects the LOCK line (GY/VT).


The motor in the fuel tank flap is directly connected to the BCM. The are two relays (1xUM each) to unlock (FUEL FLAP UNLOCK) and lock (FUEL FLAP LOCK) the flap. In idle state, both pins are grounded through the relay contacts. Depending on the commanded direction of motor rotation, one of the relays will be switched and connect the respective pin to +12V rail.

  1. Verify F8 and F12 fuses in the BCM.
  2. Disconnect C2 connector in the BCM.
  3. Measure impedance between pins 71 and 62 of C2 connector. If around 8 Ohms, then the motor is likely not the problem.
  4. Measure impedance between pin 71 and ground, and also check 12V rail level. If there is continuity, then the cable has been compromised. Repeat the same measurement with pin 62.
  5. Apply 12V directly from the battery or a battery charger to the brown BCM connector 12V pin. It should be possible to hear the fuel tank flap motor move. Revert polarity to switch between opening and closing.
  6. To reach the fuel tank flap lock mechanism, it is necessary to remove the panel in the rear right side of the trunk.
  • en/artikel/tankklappen-verriegelung/start.txt
  • Last modified: Wed. 30.01.2019 08:46
  • by jphid