You can try disconnecting the battery for 5 minutes, that's how it's reset on a 1991.
Buick didn't make a Rainier in 1994
vehicle will not start how do I reset the computer you don't need to
The 1994 Buick engine control computer is located behind the passenger side dashboard. You will need to remove the glovebox in order to access the computer.
To reset the computer in a 2005 Buick Rendezvous, you can disconnect the negative battery cable for about 10-15 minutes. This will clear any stored codes and reset the system. After reconnecting the battery, start the vehicle and allow it to idle for a few minutes to enable the computer to recalibrate. Make sure to check for any warning lights after the reset.
On my 1994 Lesabre it is under the dash about center at edge of carpeting
Unhook the negative cable and wait ten minutes, the computer is reset.
You would need to disconnect the battery for at least 5 minutes. This should reset the computer system back to manufacturer settings.
To reset the computer codes on a 2001 Buick LeSabre, you can disconnect the negative battery cable and leave it off for about 15 minutes. This will clear the memory and reset the computer. After reconnecting the cable, start the vehicle to see if the check engine light is off. If the light persists, it may indicate an ongoing issue that needs to be addressed.
with hand held computer (scanner)
Disconnect the battery for a few seconds, then reconnect.
I think you just disconnect the battery then reconnect
the older cars u can unhook the battery for 15 minutes but with the new computers in the cars today u have to unhook them for 30 to 45 minutes then it will reset the computer