Audi S8 D2 RNS-D - changing video input on the move

[JimS8]

I eventually got round to rigging up my Pure Highway and mp3 player to play through the RNS-D Nav+ unit using the method helpfully suggested by craigyb last year here -

http://www.tyresmoke.net/forum/car-electronics-satnav-i-c-e-multimedia/107174-s8-rns-d-line-connection.html

i.e. by connecting the audio leads into the TV/AV input, and so AV1 is now my DAB and AV2 is the mp3 player and I can switch between the two in the TV set up screen. The only slight drawback I have found is that once the car gets moving, I get the screen that tells me that I can't watch the screen for safety reasons and it then goes to the satnav screen, and so I cannot get into the set up menu and so can't switch between AV1 and AV2 unless the car slows right down or stops.

Does anyone know a way of getting round this problem?

Jim

[craigyb]

You can cut the gala wire on pin 1 of the power connector, put a switch on it and that will give you TV in motion.

I used the rear blind position to control the TV in motion, but it requires a bank of relays to control it as the switch is momentary.

[JimS8]

Many thanks for the quick response.

Having done a bit of research since reading your reply, I gather that it is the GALA wire that triggers the disabling of the TV picture, but that disconnecting it stops the modification of the volume as the car speeds up and may also have an adverse effect on the satnav, hence it is desirable to fit a switch rather than just disconnecting it.

What I don't understand is the bit where you say "it requires a bank of relays to control it as the switch is momentary". Forgive my ignorance as I am a novice with auto electrics, but does something else have to be connected into the circuit in addition to the switch and if so, what?

Thanks

[craigyb]

Obviously the main problem is that the Audi dash switches are all momentary, so pressing the switch closes the connection but as soon as you let go it's open again. This needs to be made into a latching switch, one push closed, one push open. This allows TV in motion to be switched on and off, the default being off so the navigation position and volume GALA is not affected until you turn the TV in otion on. In fact with the RNS-D having two sources for speed pulses, cutting the single GALA wire doesn't affect NAV updates, but it does affect GALA, it's only on the RNS-E where it has one GALA input that cutting the GALA affects NAV updates.

The relays act as a latching mechanism for the momentary switch, I think altogether I used 5 relays and 2 diodes to make a latching switch from a momentary push. The beauty of which is it is only functional when power is applied to the car, so it always defaults to normal when the key is removed.

I have the diagram for the circuit I found on 12volt.com, the relays cost about £1.50 each from Maplins, along with 2 power diodes IN40001 etc. The switch was £12 from Audi for the head rest (not rear blind) switch, this can also be illuminated by taking a feed from the adjacent switches for lighting.

Although the circuit below only shows 4 relays, you use the 5th to open/close the circuit, it's coil being energised by the output form the 4 relay bank below.

Edited May 5, 2009 by craigyb