need wiring help!

jackdietze10

Member
:
2002 MazdaSpeed Protege5
Hello all.

I just bought an 02 protege5 and the more i look at it, the more i find has been done to it. For example, one of the previous owners installed a siren in the grille, the wiring to which no longer functions, but nonetheless is there. The same guy, i assume, put in an aftermarket receiver and kinda completely botched the wiring. The receiver resets to factory and goes through demo mode every time the car is turned on. It's fricken annoying. I've been trying to narrow down possibilities by going through the wires myself. Here's what i've discovered.

The ground cable is completely useless. It does not have any voltage ever.
The stereo only turns on when both constant voltage power wires (from the car and from the deck) are in contact with both ignition power wires.
When the ignition power wire from the car is in contact with the constant power wire from the deck, the stereo does not turn on, however, the dome light works and the beeping to tell you the door is open also works.
When the wires are done properly, (constant to constant, ignition to ignition, ground to ground) the stereo has no power and the dome lights and door alert do not function.

It's kinda looking to me like this guy messed up the wiring elsewhere in order to, idk, put in a siren or some other essential like that paramount to having a working stereo. I hope that's not the case because if it was, there are a million different places he could have frigged it up and it could take me as many years to find it. I'm posting in hope that someone else sees something i don't and can point me in the right direction to having my stereo work!

Thanks in advance
 
If it were me I would disconnect the stereo, tape off the wires leading to it and start over.

Get B+ from the battery or a fuse under the dash,... separate ground from a good spot even straight from the battery,... then find a wire from the fuse panel under the steering wheel to get your ignition source,... That fuse will be powered only when the key is on.

You can connect all three wires right behind the fuse panel, if you prefer, then feed them to your stereo,... you can get ground from under a bolt that holds one of the relays. Make sure you connect ground to the metal casing of the stereo itself too,... I had a car once where the head unit was only grounded through the antennas ground.

It sounds like your car will work "normally" if you disconnect the stereo, so you shouldn't have to try to figure out what the PO did.
 
Thanks for your help! I forgot to check the forum for a thousand years after i figured it out. Turns out the only problem was that the constant power circuit in the car was screwed somehow so i ran a lead straight from the battery and connected it behind the stereo and voila. It all works. In retrospect it should have been obvious but oh well.
 
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