Electrical/anti-theft alarm goes off and will not let the car start

This may be an add on alarm system issue. Did you notice any wires tapped in to when you replace the switch?

Something has triggered your anti theft system, the best way to diagnose this is to use a scan tool that can show the inputs and what they read to find out what has triggered the alarm. Also the system is tied in to the lighting control module, which is a known problem and can cause various faults. I've attached the wire diagrams so you can see how it ties in.

Here are the steps for transmitter programming:

1. Enter the five-digit permanent code into keyless entry keypad (14A626).

A. Within five seconds, press 1/2 switch.
B. Within five seconds, press any button on the first transmitter. The locks will cycle to confirm successful programming.
C. Within five seconds, press any button on the second transmitter.
D. Repeat step c for each additional transmitter (up to four total).
E. Press 7/8 and 9/0 together to end the programming session or wait more than 7.5 seconds.