WHILE DRIVING TRANSMISSION GOES FROM DRIVE TO NEUTRAL..DOORS UNLOCK AND GOES BACK TO LOCK,ALSO I GET SERVIVE BRAKE SYSTEM IN THE MESSAGE CENTER

go to chevy dealer
this is a dangerous car, take , Ralf Nader with you.
author of old book Unsafe at any speed..

chevy should hid their head in shame. for such danger
bad programming for sure.
they may have a recall fix for free, seems it should to me.

Though it will not harm your transmission to shift into Neutral while your vehicle is in motion, the additional wear on your brakes by leaving the transmission in Drive will be negligible over the life of the brake pads. It is that minor. NEVER, EVER go into neutral while slowing down to a stop, for 3 reasons: 1.
https://mechanics.stackexchange.com/questions/3902/automatic-transmission-is-shifting-to-neutral-while-approaching-stops-bad

Here are the 3 engines listed for this year. IGNITION TIMING

2002 Nissan/Datsun Truck Frontier Pickup 2WD 2.4L SFI 4cyl

The Ignition Timing

18-22 DegreesBefore top dead center - When throttle positionsensor disconnected and using suitably programmedscan tool.When adjusting idle speed, set parking brake & chock drive wheels, curb idle speed (750-850 RPM)transmission in neutral.

IGNITION TIMING

2002 Nissan/Datsun Truck Frontier Pickup 2WD 3.3L SFI 6cyl

The Ignition Timing

8-12 DegreesBefore top dead center - throttle position sensorharness disconnected.When adjusting idle speed, set parking brake & chock drive wheels, curb idle speed (700-800 RPM)transmission in neutral.

IGNITION TIMING

2002 Nissan/Datsun Truck Frontier Pickup 2WD 3.3L SFI SC 6cyl

The Ignition Timing

8-12 DegreesBefore top dead center - throttle position sensorharness disconnected.When adjusting idle speed, set parking brake & chockdrive wheels, curb idle speed (700-800 RPM)transmission in neutral.

Intermittent connection problem inside the neutral safety switch.

The indicator for park/neutral is changing on the dash without you moving the shifter?
If so...the park/neutral switch on the transmission...(or could be on shifter housing) is informing the lock control module/body module... that the vehicle has been put in park...thus the door unlock actuation...then..apparently the switch is erroneously informing the lock module that it is in neutral...drive...thus locking the doors....could also be a fault in the general body module...which ..most likely...controls most of the body systems via CAN BUS....Controller Area Network system....
Odd that no codes are in the body/lock module....make sure your scan tool is indeed able to access the body control systems...if not...you need to find a location that will provide that service.

if it has automatic lock in hubs only!! start truck, put truck in neutral, push button for 2x2 shift into reverse,back up 5to 10 feet,truck should shift back into 2x2 automatically. shift into drive and the 4x4 light should go off. if you have manual lock hubs you''ll need to unlock those manually on the 2 front wheels.w/truck in neutral and emergency brake on or someone holdling brake inside truck,go to front and rotate the locking hubs to front tire or wheels in centerof hub to free wheel.they will be marked,or should be. if not,then try turning the center of hub switch counter clockwise until it stops turning,then go to passenger side and turn it counter clockwise. thank you for choosing fixya.

FOUR-WHEEL DRIVE SYSTEM

(a) Four-wheel drive control

Use the four-wheel drive control lever and center

differential lock button to select the following transfer and

center differential modes.

The "H" and "L" position of the four-wheel drive control lever

provides either lock or unlock mode of the center differential

depending on the center differential lock button position.

Use the center differential lock system if your wheels get stuck

in a ditch, or when you are driving on a slippery or bumpy

surface. When the center differential is locked, the vehicle

stability control system is automatically turned off and the

center differential lock and "VSC OFF" indicator lights come on

because the function that controls engine performance

As soon as the center differential lock switch is turned

on, the "VSC OFF" indicator light comes on. After the

wheels are out of the ditch or off the slippery or bumpy

surface, turn the center differential lock switch off.

Make sure the center differential lock indicator light and

vehicle stability control system off indicator light turn

off.

"H" (high speed position, center differential unlocked):

Lever at "H", center differential lock button left out

Use this for normal driving on all types of roads, from dry

hard-surfaced roads to wet, icy or snow-covered roads. This

position gives greater economy, quietest ride, least wear and

better vehicle control.

"H" (high speed position, center differential locked): Lever

at "H", center differential lock button pushed in

Use this for greater traction when you experience a loss of

power, such as wheel slipping, in the center differential unlock

mode.

"N" (neutral position): Lever at "N"

No power is delivered to the wheels. The vehicle must be

stopped.

"L" (low speed position, center differential unlocked):

Lever at "L", center differential lock button left out

Use this for maximum power and traction. Use this for climbing

or descending steep hills, off-road driving, and hard pulling in

sand or mud.

In this mode, the braking feeling that occurs when the wheels

are negotiating a sharp corner is further reduced than in the "L"

(low position, center differential locked) mode.

"L" (low speed position, center differential locked): Lever

at "L", center differential lock button pushed in

Use this for maximum power and traction. Use this for hard

pulling in situations the vehicle cannot negotiate even in the "L"

(low speed position, center differential unlocked) mode. Also,

using this mode when driving down steep off-road inclines will

help contribute to increased vehicle stability.

https://secure.drivers.lexus.com/lexusdrivers/info/my-lexus/resources/submit-owners-manual-search.do

Please copy and paste the link above and it will take you to the lexus site. There you will find the owners manual and you can download whatever sections you need for free.

Hope this helps.

sounds like your bcm is internally malfunctioning

The Central Electronics module is detecting a fault in on of the door locks. Its not necessary that the lock is faulty, it may just need to be adjusted. To be more specific, the locking knob that goes up when vehicle is unlocked and goes down when locked , is connected via a linkage to a microswitch on the door lock actuator. The microswitch has three positions. top position is unlocked, center is neutral, bottom is locked. However after any cycle of the lock/unlock switch, the microswitch has to return to the neutral position for it function correctly. Most likely your vehicles drivers door lock microswitch does not return to the center/neutral position after you lock you car which causes the alarm to go off. In this case you should have the drivers door lock assembly replaced by a good knowledgeable workshop, and the dealer isnt one of them.

As far as I know the procedure should go something like this...

Stop the vehicle, engage the parking brake and if applicable, get out and turn the hubs on the front wheels from Free, to Lock.(You may not have these on a Suzuki, they may be auto-lockers)

Get back in the vehicle and put the transmission shift selector into Neutral.

If you have a manual transfer case, move the selector-shaft to 4x4-High, or 4x4-Low -- whichever is desired. Now, putting the vehicle in gear with the transfer case is sometimes somewhat difficult. As long as the vehicle's transmission is in neutral, don't worry, the gears inside the transfer case are big and beefy -- Don't be afraid to be rough -- Again as long as the transmission is in neutral. You may also have to disengage the parking brake and slightly let the vehicle roll forward or back with your foot-brake to get the Transfer case to lock into place.

Once 4x4 of the selected High, Or Low range is selected, usually indicated by the vehicle jerking slightly with a slightly loud clank/thud. Move the Transmission selector out of neutral into your desired gear (Drive if Automatic, if Manual, whichever gear you pull out from). and voila! You should now be in 4-Wheel-Drive.

To disengage 4-Wheel-Drive. Just reverse the steps.