Electrical folding trailer tow hitch

The electrical folding trailer tow hitch is an element of the optional extra 'trailer tow hitch with articulated ball head'. This optional extra has been offered for the E9x since 03/2007. The electrical folding trailer tow hitch is operated using a button in the luggage compartment.

Fig 1: Identifying Luggage Compartment Trim Panel And Indicator Lamp

Courtesy of BMW OF NORTH AMERICA, INC.

The graphic shows the E90

There is a two-color LED for the indicator lamp in the button. The following signalling is possible:

• The LED lights up green  : The trailer tow hitch is in the locked end position.
• The LED flashes slowly red  (2 Hz): The trailer tow hitch is not in the locked end position.
• The LED flashes quickly red  (4 Hz):
  • The drive has been activated for longer than 4 seconds.
  • The current for the drive necessary for release has not been reached (12 Amperes).

The drive for the trailer tow hitch release is attached to the release unit. The ball head can only be released if the following conditions have been met:

• Terminal 15 OFF
• Tailgate open

The trailer tow hitch can be operated as of terminal 30 switched ON. The following signal states must be present:

• Terminal 30 switched: high signal
• Button for trailer coupling release: low signal
• Terminal 15: low signal
• Rear lid contact switch: low signal
• Micro-switch of trailer tow hitch release, output 1: low signal
• Micro-switch of trailer tow hitch release, output 2: high signal

After a successful check of the signal states, the direct current motor for the trailer tow hitch release is activated.

Fig 2: Identifying Trailer Coupling Release Drive And Ball Head

Courtesy of BMW OF NORTH AMERICA, INC.

The graphic shows the E90

The drive for the trailer tow hitch release consists of a direct current motor and a reduction gear. The following components are integrated in the release unit:

• Micro-switch with slide and compression spring
• Drive disc for the microswitch
• Drive disc for the release lever
• Release lever
  Fig 3: Identifying Compression Spring, Microswitch And Drive Shaft

  Courtesy of BMW OF NORTH AMERICA, INC.

The graphic shows the E90