Definition
The VW fault codes “P27F500: Magnet 1 for selector lever lock stuck open “ & “P082B00: Selector lever sensor 1 for X position short circuit to ground in vehicles with MQB Evo platform and DSG transmission indicate a malfunction of the selector lever lock magnet.
This means that the magnet, which locks the cable of the pawl in the P position, does not close sporadically or permanently. This means that it is no longer possible to park the vehicle safely with the parking lock activated in the transmission.
The vehicle must also be secured using the electronic parking brake. Furthermore, incorrect operation of the vehicle due to premature release of the brake when starting the engine cannot be prevented.
Sytem description
VW’s shift-by-wire system shifts gears in DSG and automatic transmissions via electrical impulses, which are transmitted from the selector lever in the centre console to the transmission control unit via data bus cables. Only paddle shifters on the steering wheel are available for manual shifting of forward gears.
This information is also transmitted via the CAN network from the steering column module to the transmission control unit via a CAN cable. The mechanical selector lever, the P position and the Tiptronic gate have been eliminated. For safety reasons, the parking lock is still operated electromechanically to prevent incorrect operation of the vehicle when starting and parking. In an emergency, it is possible to unlock this using a service routine.
Fault description
The actuator for the parking lock, consisting of the drive for the cable and the locking mechanism with the locking magnet, is located under the shift-by-wire module in the centre console.
The shift-by-wire module controls and monitors the magnet for the parking lock. When the system activates the parking lock, the output stage in the shift-by-wire module is activated and the circuit with the lock magnet is closed.
At the same time, the system monitors the voltage drop in the circuit. If this does not occur and the parking lock mechanism is not locked, the system sets the fault “P082B00: selector lever sensor 1 for X position short circuit to ground‘ and ’P27F500: magnet 1 for selector lever lock stuck open”. Both faults can be sporadic or static.
The faults initially occur depending on the temperature.
Diagnosis/measurements
Read out the transmission control unit’s fault memory and evaluate the frequency counter for the stored faults. If the counter increases after each driving cycle, the fault is current. If faults relating to the power supply are stored at the same time, these must be dealt with as a priority.
The corresponding parameters can be called up to confirm the faults. The fault may be triggered by shaking the centre console in the area of the actuator module.
Repair indication
Experience has shown that the faults are the result of insufficient contact between the locking magnet and the receptacle in the module.
To visually inspect and repair, remove the shift-by-wire module and the parking lock magnet located underneath it from the actuator module to gain access to the contacts.
After making the corrections, fit the locking magnet and install the shift-by-wire module. Then carry out a function test. Clear the fault memory.
