[Panzermann]

I’ve never had it confirmed but I suspect the spare lead is for audio out - presumably for the RT onboard speakers.

The supply to the cradle is 12V rather than 5V.

 

[Panzermann]

Hmmmmm. Is there a way to use that to wire in a jack for headphones?

It was only an assumption on my part.

If correct, I expect it would be line level, requiring an amplifier to feed headphones or speakers. You’d be better off connecting headphones via Bluetooth directly to the Nav.

 

[Panzermann]

My understanding is the Nav unit is powered by 12VDC, @Selby

 

[Panzermann]

Thank you Panzermann and Don.
Further investigation:

• I measured the voltage supplied by the bike system to the Nav 6 MOUNT via the blue plug connection and it is indeed 12 volts (by multi-meter).
• Built into the oem Nav 6 mount there must be a transformer to reduce voltage to the Nav 6 GPS to 5v as required. See Nav 6 spec in photo.
• My many past gps’s have been 5v as is the Zumo XT.
• It would be a costly mistake to assume power supplied to the Nav 6 mount by the bike system is 5v and if this supply were connected directly to an after market (non-oem) 5v gps.
• However, the bike supply can be conveniently connected to say a Zumo, via the Zumo 5v transformer. This is my next job.

Thanks again.
Selby.

Nav 6 spec below.
View attachment 119373

If you look at the cell above your arrowed cell, Selby, you'll see that power supply from the vehicle for normal use, via the pins on the back of the device, is 8-28 Vdc - pin 18 and GND on the image I posted (pass through).

The USB power is normally only used when connecting the unit to a computer.