396 Cradle Power Supply

[sola_bristol]

I have a 396 which is just over 2 years old. The cradle is connected to the bike power via the horn and until recently has worked without a problem. In recent weeks on bike start-up, locking the unit in the cradle and turning on the ignition didn't "wake up" the unit which had to be turned on manually operating on battery. Thus far the bike power seems to have connected at some point during the ride after which it worked fine as normal but each new start is the same. I have been trying to get to the bottom of the problem over this weekend. I first assumed it was a problem with the power supply to the cradle. I used an avimeter to determine the voltage at the cradle contact points with the ignition turned on and its 5.7 volts. Is that what its supposed to be?
Thinking now that the problem was with the unit rather than the power supply I have renewed the XML file and master re-setted. After that, the unit wakes from the "stand-by" mode but not the "switched off mode". Moreover, having woken, in response to the ignition turn on, the unit doesn't react when the ignition is turned off with the usual message about "external power turned off etc".
I think I can't go much further with this until I can be sure if its the unit or the power supply. I see there's what I assume to be a relay box as part of the wiring for the cradle and don't know if that might be faulty. Does anyone have any thoughts or ideas on how to locate the problem?

[sola_bristol]

Have been on the Garmin chat line and they've decided the unit needs to be replaced so I get a discounted exchange price of £95 inc VAT...........so I've done that