I believe the only way to reset the ECU for 00-01 is disconnecting the positive battery terminal. If you take it off overnight and the ECU still isn't reset then you can try the following procedure, BUT I think that the following procedure only works on 2002 and up. You should know that your ECU is reset just by the way it drives, you will def feel a difference, especially since its an auto, on the way it shifts at first and where it shifts.
How to reset ECU in 5th and 6th Generation Maxima's
1. Turn ignition switch on and wait about 3 seconds.
Repeat the following steps (2a and 2b) procedures quickly five times within 5 seconds.
2a. Fully depress the accelerator pedal (HARD).
2b. Fully release the accelerator pedal.
3. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 10 seconds until the CEL starts blinking. (here is where i think you can get a code from this.)
4. Fully release the accelerator pedal (while the CEL is still blinking)
5. Wait about 10 second.
6. Fully depress the accelerator pedal and keep it for more than 10 seconds.
7. Fully release the accelerator pedal (The CEL light will continue to blink).
8. Turn ignition switch to “OFF” position and now you can start the car. The CEL light should be gone.
Here is also the thread I got the procedure from if you want to do some reading about it: