Car Alarms: 98 Toyota Tacoma, valet mode, toyota tacoma

Question
I just changed the battery on my husband's recently purchased 98 Toyota Tacoma and now I can't start it because the alarm keeps going off. I just bought the truck for him used and the previous owner doesn't know anything about the alarm, nor is it mentioned in the owner's manual, although it was originally equipped with the alarm. The key has two buttons, one larger than the other, but pushing neither button will disable the alarm. I tried using a spare key (one without a button) and it won't even turn in the ignition. There is a switch on the left driver floorboard, which does not disable the system to allow it to start (although you can't turn the key if the switch is in the lower position) and there is a button above the toggle switch that doesn't seem to do anything. I currently have the positive battery terminal disconnected in hopes this helps reset the alarm, but I need answers quickly :) My husband comes home from working overseas tomorrow and I need that truck running! Thanks a bunch.
Angela

Answer
Typically you would have to have the ignition key turned to the run position for those switches you are referring to to work.  Try flipping the switch under the dash with the key in the run position.  If there is an LED mounted in the vehicle it should light solid to indicate the system has been put into valet mode.

The 1998 Tacoma did not come with a factory alarm, so this is either a dealer installed item or it was installed after market.  If you take a look under the dash at the ignition wiring harness you should see where wires were tapped in to supply the system.  Tracing these wires back should lead you to the brain, disconnecting the brain should also disarm your alarm.  The easiest way to disconnect the brain would be to pull the fuses supplying it.

To the fact that you can not turn the key, this is odd because I have not seen a system that operates like that.  However if there is an electronic lock on the key switch it could be that they interfaced with that wiring to disable it when the switch is not in the correct position.