A&Q about 350Z
Q:
Hi Guys. I have a '91 2.0 16V mk2 gti and i have recently fitted a cd player and amp (running rear speakers only). The amp is wired directly to the battery (positive and earth) and there is an inline fuse in the positive.The amp is currently just sitting loosely in the boot i.e not bolted in but i'm not using car at moment. If i turn on the ignition and turn on my cd player the sound is excellent,but if i either turn on my lights or start the car, the amp dies and i only have front speakers??? There is a new battery in the car also. Am i missing something simple or is there a problem with the amp??? The amp was working fine in my mates car previously.Please help
A:
The earth cable shouldn't be wired to the battery as the other post is a negative not earth. The cable needs to be attached to the body of the car with preferably a bit of paint rubbed off around the screw for a good connection. As it is wired incorrectly it'll be earthing when the lights are turned on which is why its then turning off.
A:
Ok, Thank you very much for the info. I'm a little baffled though as to why it would make a difference whether i connect the black wire to negative or earth??? Are they not one in the same?? I'm not doubting you, I just don't quite understand. Thanks Mate
A:
Negative and earth are different, negative is needed to complete the circuit where as earth is basically required when things go wrong. You turning the lights on is causing the current for the amp to go the wrong way which is why its effectively turning off. Have a look in the manual for the amp which'll no doubt explain it better than me.
A:
Ok. Put earth for amp onto same bolt thet earths the central locking pump but amp still cutting out????????????????????????????????????
A:
Anyone any ideas
A:
Anyone any ideas
Personally I would bolt the earth wire securely to a bare piece of metal under the rear seat, earthed on it's own. Make sure the connection is squeaky clean and bolt/screw it down tight and it should be just fine.
The other factors to take in to account is wether you have sufficient thickness of power lead to the amp.
What model amp is it and what RMS does it put out, plus what gauge of power cable are you running? - let me know the model of the amp I can then tell you what size cable you need.
You will also have somewhere on the amp an led marked 'protection' - does this flash when the car is not running and the sounds are at, say, half volume or more? - if so then that's a warning sign that something isnt quite right. Keep us posted.
A:
there's nothing wrong with earthing amp back to the battery
A:
Thanks guys. I didn't think that there would be a problem earthing the amp back to the battery but i'm not too familure with the wiring of amps. The amp is jvc but i'll find out the model number tomorrow. I think you may be correct with regard to the gauge of wire as the wire coming out of the amp (red and black) is a certain thickness but the wires that are joined onto those to go up the battery seem a fair bit lighter. Very much appreciate the help guys
A:
Negative and earth are different, negative is needed to complete the circuit where as earth is basically required when things go wrong. You turning the lights on is causing the current for the amp to go the wrong way which is why its effectively turning off. Have a look in the manual for the amp which'll no doubt explain it better than me.
Uhm?
"Earth" is battery negative...
Battery negative is connected to the body shell, which then becomes one big "conductor" that various equipment picks its earth/negative supply from.
Earthing electrical equipment, especially amplifiers, to the car body saves having to run double the length of cabling, saving weight and the cost. Ask yourself, how do they manage with GRP bodied cars?
If anything, and if my memory serves me correctly, I think some installers will run the amp's negative directly to the battery to prevent electrical noise being picked up from other electrical stuff that's earthed via the bodyshell.
A:
Cheers for the info. It didn't make sence to me either. Do you have any idea as to what my problem could be???
A:
heres an idea, as you have wired the amp directly to the battery, positive and earth, a good idea btw , you must be running the remote wire from the head unit to turn it on and off. otherwise the amp is on all the time and the battery would run flat.
so the power supply to the head unit is
positive 12v live , allways on
key switch live , live with ign. on
light switch live , goes to 12v with lights on
gnd.
out puts are
rem , remote switch , goes 12v positive with head unit on
speakers e.t.c
if the light sw. live is shorting the rem. wire, then when the lights are switched on, the amp will switch off. to check remove the rem. input from the amp. power supply and connect a small guage wire from the 12v positive supply to the rem. connection on the amp,. this will make the amp on all the time. start the car, lights e.t.c. if the amp stays on then theres your problem.
i think.
edit,
just seen the post in the elecrtical section, with a better description.
you have used an output from the head as an earth as golden said.
rewire the head unit.
A:
Hi Thanks for info. The earth from the head unit is connected to the radio earth wire in the original loom (brown) Everything else is connected as you described with the exception of the light switch live?? Don't have that connected and have it taped up in car loom and head unit. Is this wire necessary???
A:
Have actually discovered that the amp breaks down when wipers of interior fan etc are switched on?? Have thied earthing amp to battery using larger dia wire but no better. Getting really p@#]€d off with it now.
A:
Negative and earth are different, negative is needed to complete the circuit where as earth is basically required when things go wrong. You turning the lights on is causing the current for the amp to go the wrong way which is why its effectively turning off. Have a look in the manual for the amp which'll no doubt explain it better than me.
Uhm?
"Earth" is battery negative...
Battery negative is connected to the body shell, which then becomes one big "conductor" that various equipment picks its earth/negative supply from.
Earthing electrical equipment, especially amplifiers, to the car body saves having to run double the length of cabling, saving weight and the cost. Ask yourself, how do they manage with GRP bodied cars?
If anything, and if my memory serves me correctly, I think some installers will run the amp's negative directly to the battery to prevent electrical noise being picked up from other electrical stuff that's earthed via the bodyshell.
That makes sense, never really thought about it in depth before (especially GRP cars etc, never crossed my mind!) Guess I've been working on housing electrics too much lately. How much of a prat do I feel right now
A:
Ok. Looks like i'll have to rip out this amp ang go wiyh bog standard speaker setup. Pity as the sound is great when amp working
A:
I've been trying to think what could be happening here.
You said you're not using the car? Are you sure the battery is charged up enough? If the amp has some sort of low battery voltage protection, it may switch itself off if turning other things on makes the voltage drop below the threshold. There can still be enough juice left in the battery to start the car and for stuff to work, but low enough to cause odd problems with eletronics.
Are you sure the head unit is wired up properly? Check the remote switch cable (blue) still has +12V when lights, etc., are turned on. If not, there's a problem with the wiring and/or the head unit.
As a reference, you should have:
Yellow - constant + (used for the memory)
Red - switched + (aux and ignition on position on key)
black - earth (brown on car)
blue - remote on/off control for amps and electric aerials, etc.
Those are the main ones (apart from speaker wires), but you may also have one that goes to sidelights, which dims the display when the lights are turned on, and a phone mute wire.
You can also wire up both red and yellow to a constant +, so that you can use the install without the key in the ignition.
A:
I would try connecting your amps remote wire to a constant live to see if that cures it. if it does then you could leave it and just fit a switch. It sounds to me like someone has badley messed about with the headunit wiring behind your dash at some point.
A:
Ok Thanks very much for info guys. I really appreciate it. It's just bugging me as to what could be wrong with the setup. I'll take on board what you recommend and keep you posted. Cheers again.
A:
Ok. Glory at last I ran a wire (fused line) to a switch on the dash and from there to the switch wire on the amp and hey presto, Impressive tunes. Thanks for all your help guys. Appreciate it.