1999 GMC Sierra reseting the computer after installing new

Hook the cable back up generic relearning and do below

#1 set the parking brake and start the engine. You can put it in park or neutral. You need to let the engine run until the cooling fan comes on or it gets up to operating temperature.

#2 After step one you will need to let the engine idle in neutral for one minute. Then you will need to let the engine run in drive for one minute. Remember not to touch the accelerator in this step and #1.

#3 Remove the parking brake and drive the car at 20%-50% throttle until it reaches top gear.

#4 Cruise at light throttle for 5 minutes.

#5 Allow for the vehicle to come to a stop, you can use the brakes if needed.