why wont my sons 2003 mazda speed protege start/

Not sure on how old battery is.i didn't check cause when I got a good connection on the positive cable...it started right up.i did not change the negative cable cause it looked ok.i did take it of and cleaned it up and put it back on. Checked the switch on the clutch pedal too.that works fine.im pretty mechanical inclined.im kinda stumped on this.u think the battery??.I was leaning mor towards the seliniod??? But when I found where it was??? Holey crap!!! How the heck ya get to it with out removing half the motor??? Any way , I'll check the battery..put my charger on it for a while .Thank u for Ur input.

Might also try jump starting it. Negative jumper cable on motor. If it then starts you either have a battery or connection issue.

Ok...thanks. why negative on motor? I understand it's grounded...but how does that explain a connection or battery issue? Just wondering .

By passes the negative cable from your battery to the frame and motor of your car.

K...thanks.ill go give it a shot

This will take your battery cable connections out of the loop when calling for the extra amps to start the car.

I had the same problem. Turns out the car is equipped with an immobilizer that get triggered if the battery is either low or disconnected. There is a tiny little button located under the dash behind the steering column. (Took me a while to find it.) You have to hold the button down while starting the car and it should start right away while resetting the immobilizer. Common problem with these cars after changing the battery.