2000 Ford explorer will not start

I went out to start my explorer this morning and it wouldn't start. I thought it was the battery so I disconnected it and had it checked. It is good. Could it be my security system? Every since I bought the explorer, I have a hard time using my key. I bought it in December.

Any ideas?

does the motor crank? if so, then it is not the battery. if there is no cranking then the battery coudl be low. or key problem. i have a key for my daughters mustang that fits the hole, but dont have the electric chip inside. the key turns, but will not crank the motor.

does the motor crank? if so, then it is not the battery. if there is no cranking then the battery coudl be low. or key problem. i have a key for my daughters mustang that fits the hole, but dont have the electric chip inside. the key turns, but will not crank the motor.

They key will turn, but it does not crank. I took the battery to the auto parts store and they said the battery was good. This has never happened before. I just went out yesterday morning and it wouldn't crank. The red light is blinking for the security system. The truck has the numbers on the door, but I never used them because I bought the Explorer used.

The same thing happend to me with my 02 explorer. The theft light kept blinking fast and it would not start. I called the dealership and he told me how to reset the alarm system. Put the key in and turn it to the on position and let it sit for a minute or so and then turn it off and take the key out. You should here a chime and the flashing should stop. He told me to do that a couple of times and it should reset. To tell you the truth though I think it is your battery. When you had it checked how many Cold cranking amps did you have left on the battery? How old is it? If it is over four years old I would replace it. I think that if the security system notices a change in the battery it thinks that the car is getting stolen therfore shutting down everything. As soon as I put a new one in mine it started right up. If that doesn't work then you might have to take it in and get it reprogrammed and get a new key cut.