I have a 2001 nissan frontier and the key is in the lock position in the ignition. how do i unlock and start the car.

The easy way is to get a local auto electrician to do it with a scan tool computer

https://www.google.com/search?q=mobile+auto+electrician+near+me

or a mobile locksmith

https://www.google.com/search?q=mobile+auto+locksmith+near+me

Or try this again with these instructions and videos

2003 Nissan Frontier Key Fob Remote Programming Instructions

1. Get inside the vehicle close and LOCK all doors using the lock/unlock switch on the driver's side door. ( ...
2. Insert your key into the ignition and remove it 6 times within 10 seconds. ...
3. Insert the key in the ignition and turn it to the ACC position.

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Sep 12, 2013

2003 Nissan Frontier Key Fob Remote Programming Instructions

There are rumors that there are "hidden" features accessible by the dealer. If this is something you dont want, contact your local dealer and ask if that is something they can turn off.

Power is supplied at all times: ? from 30A fusible link (Letter , located in the fuse and fusible link box) ? to circuit breaker terminal s1 ? through circuit breaker terminal s2 ? to power window relay terminal s5 . With ignition switch in ON or START position, power is supplied: ? through 7.5A fuse [No. located in the fuse block (J/B)] ? to power window relay terminal s2 . Ground is supplied to power window relay terminal s1 : ? through body groundssM68 andsM14 . The power window relay is energized and power is supplied: ? through power window relay terminal s3 ? to main power window and door lock/unlock switch terminal s1 , ? to power window switch RH terminal s4 .

https://www.nicoclub.com/FSM/Frontier/2000.0_Frontier-VG/el.pdf

Get a locksmith to make a key for the door. that's the only way to disarm factory alarm is by unlocking the door with a key

James, Check the attached links,instruction and guides on changing ignition, Good luck
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."
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call locksmith look need key reprograming

The shifter lever must be in either neutral or drive. The Frontier has an unlock mechanism to shift the lever if is locked.

The horn chirp can be disable by pressing the lock and unlock buttons simultaneously until the hazard lights flash, and no enable press the lock and unlock until the horn chirp.
To reprogram (enter new ID) key fob (keyless remote controller) follow the steps.
1. Close all doors and lock all doors
2. Insert and remove the key from the ignition key cylinder more than six times within 10 seconds. (The hazard warning lamp will then flash.) NOTE: Key should be withdrawn from ignition key cylinder completely each time.
NOTE: Do not rush the insertion/removal key cycling process. The side marker/tail/license lamps and interior illumination will flash twice when this step is accurately completed.
3. Insert key on ignition key cylinder and turn ignition key switch to "AAC" position At this time, the new ID code is entered and original (previous) ID codes are erase.
4. Press any button on the new remote controller once. (The hazard warning lamp will then flash)
NOTE: Do not press the button more than one time in the above step. If the button is pressed more than one time, the programming procedure will not be successful. The side marker/tail/license lamps and interior illumination will flash twice when this step is accurately completed and programming is successful.
If there is only one remote controller skip step 5.
5. Additional ID code entry Release the door lock, then lock again with door lock/unlock switch (In power window main switch)
6. Remove key from ignition
7. Unlock driver side door, open driver side door and then close the door. (END)

Yes, there is a way to reprogram your car to lock the doors when the gear selector is put into Drive.
Follow this site for a complete step by step re-program of the door locks:
http://www.nialtima.com/automatic_door_locks-113.html

IMPORTANT: Before entering programming mode, have in possession all of the
transmitters you will be using on the vehicle. Once you program the
transmitter, all previous codes will be erased from the memory. The other
transmitters will not be functional until you program the transmitters
again.

1. Close and lock all doors with the driver's side power lock/unlock
switch.

2. Insert key into ignition and remove it from the ignition key cylinder
at least six times within 10 seconds. Your Hazard
Lamps will flash if you have performed this step successfully. NOTE:
Withdraw key completely from ignition cylinder
each time. If this procedure is performed too fast, system will not
enter programming mode.

3. Insert key into the ignition cylinder and turn to the ACC position.

4. Within 5 seconds, push ANY button on the remote transmitter. Your
Hazard Lamps should flash. NOTE: Do not press
the button more than one time in the above step. If the button is
pressed more than one time, the programming
procedure will not be successful.

5. If there are any remaining transmitters (including the old ones),
unlock then lock all doors using the driver's side
power lock/unlock switch and within 5 seconds, push ANY button on the
next remote. Your Hazard Lamps should
flash. Repeat this step for each transmitter (including any existing
transmitters).

6. Turn the key to the OFF position, remove keys from the ignition, unlock
doors using the driver's side power lock/unlock switch and open the driver
side door.