New stereo - no power!

[MiniMike]

Hello, I purchased an Alpine head unit to replace the old standard cassette stereo I have in my W203.

I have the correct MB "connector" wires too. So I have connected it all up correctly, but there is no power. I then reconnected the old MB stereo to see if I had blown a fuse or something - but no, it works fine.

Then I tried my old Alpine head unit that I just took out of my Audi A4 I just sold (in case the new one was duff), but again, there is no power to this.

I am completely lost now, the connector seems fine, no loose bits or anything.

Can anyone help?

 

[grober]

Have you fallen foul of the permanent live/ ignition on live switch in the supply lines problem to the unit. Sometimes these have to be swapped before things work properly. Check for the permanent 12v on your car connection and verify this is correct for the Alpine unit. If not you may have to swap it with the 12v switched line

 

[MiniMike]

Erm, I'm not so good with this kind of stuff!

So on the "car" wires, I need to swap the permanent live with the ignition live wires?
If so, what colours do I need to swap?!

 

[grober]

Usually they are red and yellow and sometimes you can actually see inline connectors on 2 of the input lines on the radio wiring to facilitate this SWAP . But if this is all foreign territory to you I would suggest taking the car to a good ICE centre to sort it out for you since getting things wrong might damage the unit permanently. car radio connections - Google Search

Did the head unit not come with installation instructions? if not you may be able to download them by keying in the unit model number.

 

[Benzmanc]

You may not have the switched live, if so one can be obtained from the cigarette lighter. To check connect both red and yellow wires from the head unit together. Although if unsure then seek help, if you're near Manchester I can do it for you.

Daz

 

[MiniMike]

Thanks for the offer Daz, bit far for me though. I'm living in Munich at the moment!

On my new head unit I have red to red and yellow to yellow - doesn't work. On my old head unit I have red to yellow and vice-versa - doesn't work!

I've had a look at what the wires mean! I have an earth (MB = brown to Alpine = black) and the battery (MB = red/green (I think) to Alpine = yellow). But I don't have any connection to my red / ignition cable from the MB side of the connector. Could this be the problem?

 

[grober]

Can you post your alpine unit model number

You will deffo need a 12v supply to the ignition 12v input [ red] for the unit to switch on. You could temporarily run a loop from the battery red/green---yellow lead. this means the unit will be "live " all the time and you will have to switch it off manually. BUT only do this if you are sure of what you are doing.

 

[MiniMike]

It's an Alpine CDE-125BT

 

[grober]

you need a 12v supply to the red wire [5] ( ignition)------ check the MB wiring plug you may have a 12v ignition switched pin somewhere? If not its easy enough to run one

 

[MiniMike]

Great, thanks for that. What colour would it be on the MB side? Everything is completely different!

 

[Benzmanc]

As I said you don't have the ignition switched live. Simply run a wire from the cigarette lighter to the red on the alpine. Had to do this on my kenwood.

Daz

 

[grober]

Further research would indicate the Mercedes Audio10 and 20 are no longer ISO [standard] compatible and thus the MB connector plug will not have a Ignition switched 12V supply. Its probably switched on via the can [ data] bus connections. If this is the case you will have to to run a separate auxilliary ignition switched supply from the cigarette lighter as previously suggested.

 

[MiniMike]

OK, so I need to find a spare bit of wire, connect it to the wire going to the ciggy lighter (any idea what colour and how to get to the wire?), then put t'other end into the connector going to the red wire for the Alpine?

That doesn't sound too difficult!

 

[MiniMike]

I have a boxing match to watch now (it's free to watch in Germany!) so will try it out tomorrow and will let you know how I get on.

Thanks for all your help!

 

[W210 E55]

Your looking for a black/yellow wire. Pop up the gear lever surround, then ashtray assembly will unclip

 

[MiniMike]

Two hours later...completed and working!!!

Thanks for all of your help, that sneaky yellow/black wire did the trick!

Just one last question, it obviously goes off when I turn the car off. Is there any way that it will stay on even with the keys out? Or would that involve wiring the red wire to a permanent live somehow?

Thanks again!

 

[MiniMike]

Couple of pics - during and after!

 

[grober]

Two hours later...completed and working!!!

Thanks for all of your help, that sneaky yellow/black wire did the trick!

Just one last question, it obviously goes off when I turn the car off. Is there any way that it will stay on even with the keys out? Or would that involve wiring the red wire to a permanent live somehow?

Thanks again!

The answer is yes you would need a fused permanent 12v feed to the red wire. However the down side is that the head unit and any other equipment it switches would remain powered up with the ignition key removed- meaning you might flatten the battery if you left the head unit on by mistake overnight/ or for a few days for example.

 

[Benzmanc]

I presume it's a detachable front, if so then removing the front will power it and anything connected off if you wired it to work without ignition.

Daz