Forums Forums Enthusiast Forums A - Z Autowirral Sony MEX-BT3900U

Now am quite good at fitting stereos, but am having trouble working out this one.

Its the power side of things am intrested in.

See pic

3: Blue & white stripe = Amp Remote
2: Blue = Aerial Remote
6: Yellow = Permanent Live
1: Black = Neg
5: Red = Live when ignition on

Number 4 light blue has me stumped it's labeled ATT.

The ATT stands for "attenuate". It's also known as the "mute" wire. This is used only when you're installing a hands-free phone kit. Most hands-free kits for cars include an output that can be connected to the mute wire. When you receive a wireless phone call, the hands-free kit automatically mutes the car radio. Otherwise, this wire doesn't need to be connected to anything, and should be taped off so it can't contact the head unit chassis or dash metal.

Thank You.

On my Sony head unit, the ATT is a low voltage supply that switches on my amp, so if you have aftermarket amp it acts as a switch to that.

Number 3 wire in picture does that.

I have this stereo I also have the same one without the Bluetooth and both units vary on what cars you put them in.
For example if fitting in a pug 206 the red live and the yellow live need to be swapped over or the unit will not function correctly.

Same with my Astra, the red and yellow lives needed swapping over as without doing this the init would not work.

My att wires are disconnected, amp in my Astra is powered by the amp remote wire which basically just acts as a passive switch for the amp.

My Saab has an amp which is powered by wiring right into the fuse box which in turn is connected to the ignition as it still has its original stereo. This is another option when fitting your amp.

It's all sorted now, I pick up my fascia adaptor from Ford's tomorrow.

How much are ford charging for the adapter if you don't mind me asking as they can proove expensive from halfords ect?

£12

I got my adapter from fords yesterday from village motors, the adapter is for mk1 focus, but it dont fit.

I took it back and told them that i think they have given me the one for a left hand drive car, (they laughed) so i asked them to come to my car, and i showed them what i meant.

And they said, yes you are right.