When in Park, button on shifter (automatic Trans) will not press in allowing me to shift into any gear. must be a relay or something...I often can hear a clicking and if I mess with it long enough it will all the sudden be ok but seems to be getting more frequent. hoping it's something I can fix myself? any ideas?

Vehicles have a safety system that won't allow gear selector to be moved out of park unless brake pedal is pushed ! This what Buick calls there's
Automatic Transmission Shift Lock Control ! Depending on make of your vehicle it mite be called something else . But all vehicles have it.
The automatic transmission shift lock control system is a safety device that prevents an inadvertent shift out of PARK when the ignition is ON. The driver must press the brake pedal before moving the shift lever out of the PARK position. The system consists of the following components:
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The automatic transmission shift lock control solenoid

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The automatic transmission shift lock control switch

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The brake to shift relay

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The rear integration module (RIM)

With the ignition in the ON position, battery positive voltage is supplied to the brake to shift relay coil. When the RIM energizes the brake to shift relay, the brake to shift relay switch contacts close suppling battery voltage to the automatic transmission shift lock control switch. The circuit continues through the normally closed switch to the automatic transmission shift lock control solenoid. The permanently grounded solenoid is energized. This locks the shift linkage in the PARK position. When the driver presses the brake pedal, the contacts in the automatic transmission shift lock control switch open. This causes the automatic transmission shift lock control solenoid to release. This allows the shift lever to move from the PARK position.

You should definitely have to push th button to get from forward to reverse. If not the gate at the base of shifter has broken and will need to be replaced

shift lever does not move out of the PARK position with the ignition ON and the brake pedal pressed ?

First, check transmission fluid level, if low may not be able to pump, may need trans filter and fluid change.

there should be a release hole by the shifter stick a pin in it and press the button to release the shifter. if not press brake down and try to shift

models did have a shifter lock lock in the trans
if standard shift yes it could happen so use you emergency brake

It is probably not the shift linkage causing your concern. All modern vehicles have a feature called Shift Interlock. It doesn't allow the shifter on automatic equipped vehicles to be moved from park without the key in the ignition and the brake applied. There should be a bypass that will allow you to atleast drive the car for the time being. Check your owners manual to find where it is. It's usually around the shifter. The most common cause for this problem are the brake switch or the shift lock solenoid.

can you move the shifter and it wont go into gear or will the shifter not move at all?? if shifter wont move, there is an electrical solinoid that will not allow the shifter to release when the car is off, that could be faulty, i think it also has a safety mechanism that wont allow it to shift if your foot is not on the brake? if the shifter moves through prn321 but the trans wont come out of park, you have broken the shifter cableand or damaged the shifter mechanism in the trans. hope i have been of some assistance

there is a selenoid that unlocks the shifter it may be broke. you can also check your brake switch.

you have what is called a btsi, brake trans shift interlock that may be the problem, usually there is a little square cover on the console you can remove and use a screwdriver to depress the latching mechanism to shift the car out of park