2001 Ford Ranger

Computer problem
2001 Ford Ranger 6 cyl Two Wheel Drive Automatic 130000 miles

The air bag light was on. I was hit in the rear end. No significant damage and it went off.
Now there is a beeping noise fromthe dash. A series of 5 beeps and 5 times, so 25 beeps. Every fifth beep there is a slight pause.
Any ideas
December 28, 2007.

Flash code25=P1871 Passenger air bag deactivation switch fault. If you try to fix this yourself, Disconnect the NEGATIVE battery cable and wait 5 minutes before you service it.

Dec 28, 2007.