Use the cigarette lighter 9V battery device that you can buy at any auto parts store ( AutoZone, Napa, Pep Boys, Advance Auto Parts, etc.etc).
- Plug a 9V battery into the device.
- Plug device into the cigarette lighter.
- Turn ignition switch to accessories (Doesn’t matter if your cigarette lighter is ON with the ignition off or it’s OFF. This will take the confusion out)
- Get out of the car and close all doors.
- Wait 2 minutes
- Remove battery terminals, and remove old battery.
- Install new battery.
- Connect battery leads back to the new battery.
DONE !
Any more confusion ?
P.S. : Your Viper alarm does not have to be reprogrammed. It will be fine.