Quote:
Originally Posted by compu_85
One interesting thing I noticed... the remotes arm and disarm the factory alarm. Not sure how that works... I'd think to the alarm module the remote looks just like a lock plunger being pulled up, which would happen when a door is forced.
|
The factory alarm uses the door cylinder switches to arm and disarm the alarm module. The same +12/ground signal from the lock cylinders that drives the pump also goes to the alarm box and activates or deactivates the alarm. The alarm also looks at the dome light switches on the doors and trunk (or hatch for the wagon). If the alarm module sees a dome switch close while the alarm is armed it will sound. In addition the hood switch, the radio removal lead, and the tilt sensor are monitored.
The green wire goes from the door switch to the pump then to the alarm. That is why if you cut the wrong green wire at the pump the keyless will not work. You have to be between the door switch and the pump, so that both the pump and alarm are controlled by the relays in the alarm module.
The schematic above shows how the relays work. When the keyless controller is idle, the normally closed contacts are made to the commons, and the signal from the door switch is passed through to the pump and alarm module. When either the lock or unlock command is issued, the appropriate relay is energized, which interrupts the signal from the door switch and applies either +12 or ground as needed to lock or unlock.
What all this means is that the keyless controller acts like another door or trunk switch to the alarm module, so the factory alarm functions normally. Pulling up the plungers on the doors does not send the electrical signal to the alarm and pump so the alarm stays armed, and when the alarm module sees the door or trunk dome light switch contact, the alarm sounds.