[Pukmeister]

Mike,

According to the Bentley repair manual, the DSG uses the selector mechanism (E313) inside the car and the Mechatronic unit (J743) to operate the reversing lights and prevent starter motor operation unless in Park or Neutral.

There is a relay No 13 in the lower panel beneath the dashboard (Back Up Light relay J219) fitted on the bottom rail of relays on the far right. This relay handles the current for the reversing lights when operated.

Perhaps you have a poor connection to/from the relay, or the relay itself is open-circuit or has worn contacts and needs replacing?

I guess you will need to test for the presence of a pilot signal voltage to the relay primary when reverse is selected, with the aid of an assistant. If no signal is found on the Back Up Light Relay primary side when selecting reverse, I would check the connections to the selector mechanism circuit board in the centre console.

Also check for a bad earth connection downstream of the relay primary. If all good, assuming the fuse is good and +12V is provided to the relay secondary input, check output voltage and wiring continuity on the secondary circuit from the relay to the lamp holder.