GMC 1995 Jimmy Owner's Manual page 59

Operation
When you press UNLOCK, the driver's door will unlock automatically. If
you press UNLOCK again within five seconds, all doors will unlock. All
doors will lock when LOCK is pressed.
The endgate glass will unlock when the REAR button is pressed. Vehicles
with automatic transmissions must have the transmission in PARK (P).
Vehicles with manual transmission must have the parking brake engaged.
Matching Transmitter(s) To Your Vehicle
Each key chain transmitter is coded to prevent another transmitter from
unlocking your vehicle. If a transmitter is lost or stolen, a replacement can
be purchased through your dealer. Remember to bring any remaining
transmitters with you when you go to your dealer. When the dealer matches
the replacement transmitter to your vehicle, the remaining transmitters must
also be matched. Once the new transmitter is coded, the lost transmitter will
not unlock your vehicle.
You can match a transmitter to as many different vehicles as you own,
provided they are equipped with exactly the same model system. (General
Motors offers several different models of these systems on their vehicles.)
Each vehicle can have only two transmitters matched to it.
See your dealer to match transmitters to another vehicle.
Battery Replacement
Under normal use, the batteries in your key chain transmitter should last
about two years.
You can tell the batteries are weak if the transmitter won't work at the
normal range in any location. If you have to get close to your vehicle before
the transmitter works, it's probably time to change the batteries.
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