head unit to amp cable

Post Tue Mar 17, 2009 7:17 am

Hi, taking my amp to work today and wondering if there's a route the wire can take that's known to everyone before i take my 4dr e30 apart. thank you

Martin

Post Tue Mar 17, 2009 9:22 am

are you talking about the blue remote cable that tells the headunit wether its on or not

Post Tue Mar 17, 2009 9:40 am

Cable like this from the head unit to the amp. Mine has a single wire in the middle also. Not sure what that is for. lol

Post Tue Mar 17, 2009 10:01 am

the single wire is used as the remote to tell the amp when the head unit is on/off

Post Tue Mar 17, 2009 1:58 pm

Super.

I fitted the amp but no power.

Battery to B+ correct?

Remote to remote cable.

Thanks Alex!

Post Tue Mar 17, 2009 2:02 pm

What about an earth?

Post Tue Mar 17, 2009 2:17 pm

Ok, you need three wires.

Remote
Power
Earth

the Remote is usually thin blue wire that goes into the back of your head unit. As stated above, this is so you can control your amp from your head unit.

the power cable is self explanatory. Usually a thick wire coming from your battery to the amp.

Earth, any colour, should be connected to the chassis of the car. You need to find a spot with no paint/coatings so it is a direct connection to the metal.

once the three are connected one of a few things will happen. it is a process of elimination.

If you have a green power light on the amp, your good to go.

Most amps have a security device fitted which mean that it if the remote is not connected, or the earth is not connected/isnt a clean enough connection.

If there is no power at all, check your connections from your battery, and to the amp. with this connected, you should at least get a red light.

Post Tue Mar 17, 2009 4:20 pm

Thanks all.

OK connected remote , power and earth. Switch head unit on and amp does not power up. No power light at all. Checked fuses and it's OK.

Dumb question maybe but does it need speakers connected?

Otherwise it's new amp time

It used to work I know that.

Post Tue Mar 17, 2009 4:50 pm

is the remote connected to a blue wire on the back of radio and REM on amp

Post Tue Mar 17, 2009 5:02 pm

You got a multimeter?

Or if you know you're getting power to your permo live then bridge it to the remote with some pliers to see if it does work

Post Tue Mar 17, 2009 5:13 pm

no speakers needs to be connected to an amp to turn it on.

take a short piece of wire and short the positive terminal to the remote terminal at the amp (without the blue remote lead connected) DO NOT touch the negative!!!!

if this does not turn it on then the amp power connections are not correct, or the amp is broken. If this turns on the amp then the problem could be your headunit or the connection from remote on your head unit to the amp, if you have an electric ariel that works then try connecting the remote wire to that to see it that makes it work (but not always a good solution as your amp may only be on with th radio not the CD/etc)

no one has mentioned but you should put an inline fuse as close to the battery positive as possible (this way you protect the live wire too thus preventing car fires once if the insulation wears through) there may or may not be a fuse on the amp itself - DO NOT rely on this, put an addition fuse next to battery of the same rating.

as for running the lead the easiest i found was to remove the centre handbreak surround (one 10mm nut under the ashtray) then remove the gearlever surround (one 10mm nut visible when you remove the handbreak surround) and two screw under the heater controls and two plastic clips down in the footwell, remove the gear lever (pulls off) then remove the rear seat base (just pulls up) then thread the RCA cable under the carpet to come out under the rear seat, then easy to get into the boot.

I am just about to do a wiki article on it if you can wait a week or so.

mrlee

Post Tue Mar 17, 2009 7:26 pm

Mrlee, u beat me to it. I was going to ask if you have a fuse in place to protect the Battery. If you do, check it. If not, take it to a local dealer ask him to take a look he should figure it out sharpish. Depending on the guy might costs you £20 quid or so.

Post Wed Mar 18, 2009 4:30 pm

Thanks all. I had the romote connected at the head unit. in other words I guessed wrong and the correct wire was something else.

So now I have power. Nothing out of speakers.

I have a RCA Pre out on the head unit. I don't understand the problem now

Post Wed Mar 18, 2009 4:54 pm

is the output level on the amp turned up?
Is the preout on the headunit turned on? (some HU have this function but not all)
Are the speakers connected correctly?

if not then plug any other device into the amp that has the red/white RCA leads such as your home DVD/CD player/ipod etc and see if you get any sound output from them.

mrlee

Post Wed Mar 18, 2009 5:52 pm

Afraid I don't have anything else to plug into it. I found the menu and rear out is on. Now it says S/W on back on the player. Does that mean no amp output?

Also tested another player (also 2 ports) and nothing. I have a 3rd but it's panasonic and I can't find the cable but that has 3 sockets.

:S

Post Wed Mar 18, 2009 6:09 pm

very hard to say without knowing your head unit. my unit (alpine 9880) for example has three RCA outputs one for front one rear and one sub. i can turn each one on or off, i can also turn off the internal (headunit) amp, so if your is similar it could just be a setting issue, that why i suggested to plug a known source into the amp to rule out a problem with that.

only other way i can think of is if you take a fairly flat 1.5 volt battery and connect one side to the middle of the RCA lead and touch the other to the outer of the lead you will hear a thump if your amp is working.

mrlee

Post Wed Mar 18, 2009 11:45 pm

The one with USB is what I been trying to use (kenwood) also my old Kenwood does nothing for the amp and it used to work out the box... Hmm I'll test the rca trick tomorrow. cheers

martin

Post Thu Mar 19, 2009 7:30 am

the kenwood you show the rear of cannot run rear speakers as it only has a subwoofer output, this must be turned on by the menu to get any signal from it. but even plugged in you should hear something out of the speaker connected to the amp, you also realise (i assume!!) that you only have one speaker connected??!!

but on a good note this amp has a high level input, look at the 'high in' next to the 'super bass'. this high in allows you to run the amp from the output of your head unit amp. so you would wire the rear right + and - speaker wires driectly from your head unit to the R + and - high input, and same with left + and - . then from the amp to the speakers in the normal fashion. you will need to find the 4 pin plug which will come with short length of wire to connect to, try the dealer shop otherwise go to an electronics supply shop (or brouse the RS componant website) i have sort of drawn it below!!!

This is the best set up for your system as you show me.

then later is cash allows run a sperate amp from the S/W output on HU to amp and this will run a sub woofer.

Post Thu Mar 19, 2009 5:40 pm

Well it must be shagged then! It's blowing the fuse (inline from battery) I bridged that fuse and the protection light comes on.

Odd I never noticed the fuse had blown because the power light was ON. I guess the romote has voltage.

Get another amp at some point then.

Thank you all for the massive help!!!!!!!!

Post Thu Mar 19, 2009 6:10 pm

have it checked first. the remote does have a voltage of about 12V but it is only a voltage for signal (i.e. to turn the amp on) no power can be drawn from this supply. if you have the green light on (as in the pic above) then it is on. i would not throw it away yet! what make is it, is there a local dealer/electronics specialist who can look at it?

otherwise good luck with the next one!

mrlee