You need the prom that matches your car otherwise the computer is useless. Since you don't have that it is going to be difficult to get it matched so let the mechanic do it and hope he knows how to get it working correctly.
No. People ignore car alarms. False alarms are so common that car alarms no longer cause anyone to even look out the window any longer. Alarms are not effective at preventing theft, even a little.
--scott
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