here is a link to the owners manual, read the section starting at 2-6
http://www.pontiac.com/content/dam/...ontana/2002-pontiac-montana-owners-manual.pdf
there are a few sections that cover the normal operation of the locks that could be set up in a way that your not used to.
Go through the entire door locking section and subsections make sure the vehicle is setup according to the way you expect. if you are experiencing a problem that requires diagnostics and or work to sort out we will try and help.
Below is a example of a sub section worth looking into. ( before taking your vehicle apart)
Lockout Deterrent
The lockout deterrent feature makes it difficult for you
to lock your keys in your vehicle. If the driver’s door
is open while the keys are in the ignition, a chime will
sound and you will not be able to use your power door
lock switch to lock the vehicle.
If you don’t leave the keys in the ignition or if you use
the manual door lock, you could still lock your keys
in your vehicle. Always remember to take your keys
with you.
To turn this feature off or on, see “Multifunction Alarm
Locks and Lighting Choices” in the Index.
The Automatic Level control operates the rear only, it is automatic and does not control the normal ride height. it adjust the height of the rear of the vehicle to compensate for loads by added cargo or use of a trailer .
If your entire vehicle is low because of sagging springs the level control is not designed to make up for that.
the compressor should be controlled by a switch on the rear suspension.
the fuse for this is labeled ELC/TRAILER
To know if it is working or not have someone sit on the rear bumper then turn the key on you should here the compressor run. and the vehicle should raise up then shut off.
If it raises up and your concerned there may be a leak, get a spray bottle of soapy water and spray down the air lines connections the shocks compressor head and connections.
If the compressor does not come on check for power at the related fuse with a computer safe test light on both sides of the fuse.
if you have power there, re run the test where you load the rear of the vehicle down with the key on and test for power at the compressor to ensure the switch is sending the signal to run.
If you do not have power to the compressor you can check the switch to see if it is good with a DVOM ( digital volt ohm meter )
Or just break out a factory service manual for the diagnostic flow chart that will help you pin point the problem.
Again if the whole vehicle is too low you may have to replace the springs.
Do not forget the obvious like making sure the tires are inflated and they are the correct size for the vehicle.
many times the system will develop a leak and cause the compressor to run its self to death, the previous owner may not have heard the compressor running all the time if they always had the radio turned up.
here is a small clip from the owners manual
Electronic Level Control (Option)
On vehicles equipped with the optional electronic level
control, the rear of the vehicle is automatically kept
level as you load or unload your vehicle. However, you
should still not exceed the GVWR or the GAWR.
If the engine is running or the ignition key is in
ACCESSORY or when Retained Accessory Power
(RAP) is active, you may hear the compressor
operating when you load or unload your vehicle,
and periodically as the system self-adjusts. This is
normal. See “Retained Accessory Power” in the Index.
The compressor should operate for brief periods of time.
If the sound continues for an extended period of time,
your vehicle needs service.
Using heavier suspension components to get added
durability might not change your weight ratings. Ask
your dealer to help you load your vehicle the right way
