Back Up Battery & Hood Pin Switch

Several weeks ago I installed a battery back-up to my viper 791. the diagram told me to splice the blue wire from the battery to the hood pin switch. everything seemed to work OK (alarm went off with main battery disconnected) but I guess I forgot to check to make sure the hood pin switch functioned properly. Well, today I noticed that it doesn't. when the alarm is armed and the hood is popped open the alarm doesn't go off. Yet the brain still reads ground as remote start doesn't work if the hood is open. I'm at work now but won't have time to further diagnose the problem till I get home. I think it is the battery though since that was the only time I tampered with the hood pin switch wire. Any suggestions?