HU Troubleshooting

[TBreaks]

Hi, first time installing any sort of head unit so need some help troubleshooting this issue, any help appreciated.
Car is Audi A3 2005, non-bose, rear amplified.
New head unit is Sony DAB6650. Using PC9-401 connector.
I have removed my Concert and connected up the new HU.
The problem is I see nothing at all on the HU display, no sound either.
The power connector from the car only has 2 wires, a continuous supply(red wire) and earth(black wire).
I've connected the continuous supply(red) to the yellow wire on the new HU and confirmed with a multimeter that there is 12V present even when the ignition is off.
I can put a CD into the new HU and I can hear the CD motor going as it takes the CD in. I can press the Eject button and hear the CD motor turning as it spits out the CD. So this sounds like it is getting (some)power but it should start playback when i put the CD in but nothing happens, nothing appears on the display.

What I'm wondering is, when I connect the red wire from the car(continuous supply) to the yellow on the new HU, I also have the yellow wire from the car(switched +) going to the red on the new HU. But this connection will have nothing on it since there is no connection in the car to the switched + supply. Do you reckon i need to take the 12V from somewhere and connect it to the red wire of the new HU?
There is a link below to the new HU wiring diagram, it might make it clearer.
ftp://ftp.vaio-link.com/PUB/MANUALS/CONSUMER/CDX-DAB6650_IG.PDF
Any ideas for troubleshooting ?

 

[AndyMac]

The ignition on/off function is handled via the CANBUS on newer Audi's, so, as you say, there is no separate "ignition on" supply on the Audi loom.
There are 3 solutions:
1. Buy one of these CANBUS emulators for £50
http://caraudiosecurity.com/shop/product/products_id/8074.html
2. Wire the red ignition on feed to the perm live and switch the HU on/off manually,
3. Wire in an ignition on feed so that the HU goes on/off with the ignition.
Two ways to do this. Either engine on/off functionality, so the HU will go off when you turn the engine off. to do this you just need to find a fuse in the fusebox that switches on/off with the ignition (there's plenty of them).
Or do it properly and wire in a feed from the ignition switch which will leave the HU on until you pull the keys out. This is a little more tricky as you need to identify the correct wire from the ignition switch, usually it is a very skinny red wire, much skinnier than all the other wires in the switch loom. But it could be different on later models. If you locate a skinny red wire then use a 12v testing screwdriver and a sewing needle or pin. Stick the pin into the wire and check it goes live when you turn the ignition on and stays live until you pull the keys out. Then tap into it and wire it to the trigger pin on a 12v relay and then wire the relay to the perm live and ground on the HU loom, using the remaining feed pin to power the red wire on the HU. Sounds a right pain but is actually only a 30min job.

 

[TBreaks]

Thanks Andy. After wiring the perm live to the ignition and memory lines on the new HU it works alright, even if i have to manually turn it on/off. At least i know it's working now.

 

[TBreaks]

I'm looking at the PC5-52 to get better FM reception. I was going to connect the blue power line from the PC5-52 to the Amp Remote from the HU and this will also connect to the rear amp power signal. But the amp remote from the HU has a max of 0.3Amps output. Would this be enough for both the amp and aerial connections?

 

[AndyMac]

Should be fine (remote on for the amp uses almost zero amps), but don't you have a power antenna lead on the Sony you can use just to be on the safe side?

 

[TBreaks]

Yea you're right, when the tuner is turned on it gives 12V on the power aerial lead so i can use that. Thanks for the tip.

 

[TBreaks]

I just noticed my new HU has a setting "SUBW/Rear" for the Audio output. It is set to SUBW by default but i wonder if it should be set to Rear because i have the rear amplified a3. It doesnt seem to make any difference to the sound when it change the setting but just wondering from a "could i damage anything" point of view? Or is this setting just for RCA outputs? I'm using PC9-401 so no RCAs. Thanks.

 

[AndyMac]

Yes that'll be for the RCA's as it only has two. Most HU's have 3, front/rear/sub. As yours only has 2 then you can switch the 2nd one to be either rear or sub and presumably when switched to sub it gives you some control over sub level and maybe crossover setting.