Unless you want to pay a whole lot for a transmission scanner, just bring it to a reputable transmission shop or dealer.
If the torque converter is slipping your engine will start to stall and cut out eventually you will be driving and the car will rev in the drive position as if it is in neutral go to a transmission shop and get the tech to test drive your car.
It has low oil or it has serious internal failure. With out a test drive and at leasta 1 hour diagnostic, no further can be determined.
Do a compression test.
The Test - 2001 The Etiquette Test was released on: USA: 6 June 2001
The Test - 2001 Infidelity Test was released on: USA: 4 June 2001
The Test - 2001 The Humility Test was released on: USA: 23 July 2001
The Test - 2001 The Debt Test 1-22 was released on: USA: 2001
The Test - 2001 was released on: USA: April 2001
You fill the primary/transmission oil supply with one quart of HD Sport/Trans through either the derby cover or the chain tension test cover.
To adjust the emergency brake on a 2001 Hyundai Elantra, first, locate the adjustment nut under the center console. Remove the console cover to access the nut, then tighten or loosen it as needed to achieve the desired brake tension. Ensure that the brake engages properly when pulled and releases fully when disengaged. Finally, test the brake by pulling it while the vehicle is in gear to confirm it holds the car securely.
My best guess would be for the parking break. Easy way to test, when the car is running just pull the lever or step on the lever and see what light turns on
The Test - 2001 The Dating Test 1-5 was released on:USA: 19 April 2001The Test - 2001 The Dating Test - 1.5 was released on:USA: 19 April 2001