Ground Wire on a 1999 Mazda Protege LX

[Josiah]

I need to know what wire is used as the ground on a 99 Mazda Protege LX. The thing is, the wiring diagrams for a 99 protege found on the internet don't match mine. After a lot of researching, i found that the wiring diagram for a 2003 protege does though.

http://www.modifiedlife.com/2003-mazda-protege-car-stereo-installation-diagram/

That diagram matches perfectly and states that the ground wire is black. The only solid black cord i have is a thicker wire with a clip that reads AMP. It was clipped on to the factory radio from a piece of metal that is attached to the entire frame of the head unit. That is to say, it doesn't connect to anything that would run to a chipset. All cords in the diagram are accounted for so am i wrong to assume that this black cord must be the ground wire?

Here's a pic too:

http://img524.imageshack.us/img524/1503/img00020201102081144.jpg

 

[john21]

I dont know if that is a ground wire test it with a multi meter to find out if it is use it if it is not the ground wire just make your own ground wire by finding a bolt or a piece of metal that attaches to a bigger piece of metal that eventually will somehow touch the frame which is almost everything behind the dash (i can see a piece of metal about one inch wide in the top left of your picture) by using a self tapping screw and a wire with a ring terminal or drill a hole and put a bolt through with a ring terminal with the wire attached.

 

[323_stephan]

Yeah that's the ground wire, just cut off the connector at the end and solder the wires together. I've noticed that a lot of pre-2000 Mazdas have their ground wire like yours. I replaced a HU on a 97 121 (bubble) and it had the same dealio.