missing radio fuse

[PeterGinger]

Hi folks,

I recently bought a Sony car radio (CDX700) of a mate, on the understanding that he would fit it and get it working.
This he has done. However we can't seem to manage to get the radio to save any time or settings.
Before you say anything, I know its to do with the red and yellow wires. But we tried all three possible combos with
the wires and nothing helped. He went online and did some digging. There are two fuses for the radio. One that only does the radio by itself and another one that is with heated door mirrors etc. His theory is that the one with heated mirrors etc that we don't have is deliberately left out by Renault, as its not needed. He reckons this is why there is no permanent live feed to the radio. Does anyone know anything about this, or is he talking out of his behind?

 

[BenG]

I just recently wired a head unit into my workshops 12V solar setup. I noticed there were 2 12v feeds also, one red and one yellow. According to the head unit diagram the yellow cable was wired to the ignition so I figured I should wire a switch between that and the battery and keep the red wire as a permanent live. That didn't seem to work and all the settings were lost every time I turned the head unit off. I then tried wiring the switch on the red wire and that didn't work either. It seems that both wires need to have permanent 12V supplies. I'm afraid I didn't look into it much further as it was just a case of connecting both wires to the battery.

I do know for sure that both the red and yellow cables in the car were both present when I connected the head unit up so I don't think its a case of Renault removing them.

 

[PeterGinger]

Ok. So how did the standard radio work wihout this?
I know there is someone on this forum with a high end audio setup. They must have came across this too.

 

[PeterGinger]

So I also assume that this is a problem with the car, not the stereo. Just thinking as its second hand if I'd be better off with a shiny new one.
Think I may get mark fish to fix it.

 

[BenG]

So is either the red or yellow cable missing from the plug that connects to the head unit?

Edit: sorry just re read your post.

I'd just check for voltage across the black negative wire and the red/yellow wires to rule out supply issues first. with the ignition off at least one should have 12V

 

[PeterGinger]

Ok just an update. Took the car to Mark Fish and he tested all the stereo wires; no live feed. So he soldered a wire behind the fuse box at the side of the dash on the stereo fuse. He attached the other end to the iso harness. No I have a stereo that works properly. Yay.