amplifire question: regarding possitive and negative battery wiring

[adrianfromthecastle]

i already have preexisting wires for an amplifire, so i went out and got me one. all the wires matched up for the speakers, but the possitive and negative wires that connect to the battery arent labeled. i dont know which is possitive and which is negative. so my question is, if i just guess which one is possitive and just straight plug them in, and i'm wrong, is there something bad gonna happen? or will nothing happen, and i can just switch the wires. i'd hate to follow the wires because they are already under the carpet. or is there a way of finding out which is possitive and which is negative? thanks,adrian

[zerepdivad]

i already have preexisting wires for an amplifire, so i went out and got me one. all the wires matched up for the speakers, but the possitive and negative wires that connect to the battery arent labeled. i dont know which is possitive and which is negative. so my question is, if i just guess which one is possitive and just straight plug them in, and i'm wrong, is there something bad gonna happen? or will nothing happen, and i can just switch the wires. i'd hate to follow the wires because they are already under the carpet. or is there a way of finding out which is possitive and which is negative? thanks,adrian

they shouldn't both connect to the battery.....? at least very rarely do people do ti that way one should be grounded to the chassis somewhere.. i'd say just follow the wires and see what you come put with.

[onosqv]

you could use a multimeter to do a continuity test.

One lead to wire, one lead to chassis. The one that has continuity is ground.

Double check to make sure the other one does not have continuity and spits out voltage when it is suppose to.

[benemorius]

...or even better, use the multimeter to check the voltage. A multimeter without protection could be damaged if you put it in continuity check mode and connected it to chassis ground and the positive battery wire.

If you're lazy like me, you find the closest bare metal part of the car to the wires in question (screw, trunk floor, seat bolt, etc) and very rapidly strike each wire across it. (rapidly so as not to blow the fuse, but blowing the fuse should be pretty hard as the fuse for amplifier wiring is usually 60 amps or more) The wire which sparks is positive; the wire which does nothing is ground.

[joe603]

If you can, follow the alternator lead to the battery. This is your positive. OR look for a wire bolted to the frame, this is your negative lead.

[PoorManQ45]

Take a multimeter and set it to DC ~20V(anything above 12V will do).

Touch one lead to one wire, and the other lead to a bare piece of metal on the chassis.

Repeat for the other wire.

Which ever wire gives you a reading is the positive