I have a 2001 pontiac Aztek, the parking lights and tail lights stay on when the car is off. They only go off when the battery is disconnected, the car also had a warning light "park lamp off". We have pulled the relay to the lights and they still stay on. How do I fix this problem and shut them off?

Better to do that with a high end scan tool. You can't do it by disconnecting the battery overnight, but that can cause all sort of new problems. Where you say your speedometer 'sets' at 55mph, do you mean always stays at 55 even stopped, or do you mean if 'sits' at 55 even if you are doing 110?

The most likely cause of all this the VSS (vehicle speed sensor)

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2005 Pontiac Aztek Vehicle/Transmission Speed Sensor ...

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Pontiac Aztek Vehicle Speed Sensor - GM Parts Giant

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Do you know what a wiring diagram is ? How to use a DVOM - digital volt ohm meter to test automotive electrical circuits ? That is the way to find the problem . Free wiring diagrams here http://www.bbbind.com/free-tsb

Electric Testing Techniques You Need to Know

fuses or harness connection to the rear

Switch is hung

Check brake switch near brake pedal most often it will be broken. sometimes you can try pulling up on the brake pedal to get the light to go out for a sec if that works it is the brake light switch. usually the warning light is tied to the actual light sockets it is also possible that the brake light switch went bad and from the tail lights staying on so long it may have melted the wires at the tail lights and now causing the warning light to light.

Here's a video showing you how to remove battery. Battery Replacement 2001 2005 Pontiac Aztek 2003 Pontiac Aztek 3 4L V6

This is caused by a defective return spring or a spring that has become disconnected. I am not completely sure the type this car uses. There are generally two ways this is done. The more common way today has the spring in the Mastercylinder. some vehicles, usually older ones, still use an actual coil spring to pull the pedal back. It hooks under the dash somewhere. Also some vehicles actually have adjustable switches for the tail lights if the switch is mounted down near the pedal.
I suggest that the main spring in the master cylinder is bad. Usually these are replaced as a unit.

did you check both the fuses under the dash and the ones under the hood?

Does it stay on? If so, you most likely have a bad wheel speed sensor/wheel bearing in one of the front wheels.