If the engine is not running, the brake pedal will get stiff due to no engine vacuum. If when you start the engine it remains the same, that is most likely related to the vacuum brake booster.
Now, the vehicle has a shift interlock in the vehicle to prevent the vehicle from being shifted from park by accident. The release solenoid is powered via the brake light switch. So, first check to see if the brake lights are working. If they aren't, check fuses first. The brake light fuses is located in the vehicle fuse box. It is number 9. See the attached two pics.
Here are a few links you may find helpful:
Let me know what you find.
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Thursday, February 27th, 2020 AT 3:06 PM