Disarm OEM Alarm on 1999 Grand Prix GTP

This car does not have the Passkey III transponder, all I would like to do is disable the OEM alarm.  I have attempted to connect to the 32 pin connector on the BCM, pin 5.  When I send a single negative pulse, it does actually disable the alarm, but it also unlocks all the doors, as it's part of the power door lock circut. 

Any ideas wuold be a great help.

https://www.the12volt.com/installbay/detail.asp?info=alarm&year=1999&make=Pontiac&model=Grand%20Prix&ID=18793&type=Alarm

TIA,

John

Can not get around this. The OEM alarm is integrated into the keyless entry circuit and if you take one out then you have to take both of them out.

Factory alarm on the Pontiac Grand Prix 1997 & up The factory anti-theft systems on the new Grand Prix and Grand Prix GTP are user programmable tohave control over various features like horn honk and flashing lights as well as adjusting the alarmmodes and arming and disarming modes. When these vehicles come in to your shop, they may notbe programmed to disarm with the key in the door. This of course will cause a problem as you willnot be able to disarm the factory alarm when remote starting the vehicle. This of course can berectified through the user programming, the unit can be reprogrammed to accept a ground pulse fromthe wire at the key switch in the door as well as allow arming of the alarm through the driver’s lockswitch before the door is closed.

1. Pull fuse no.27 (MALL PGM ) 10amp from instrument panel fuse block. Turn ignition switch toACCESSORY position. Ensure that seat belt indicator flashes and chime sounds 2 to 4 times.Turn parking lights on. As soon as parking lights are turned on, seat belt indicator will flash andchime will sound the number of times equal to the current mode number.2. The mode will advance, each time the parking lights are turned on and off. Passing mode 4 willbring you back to mode 1. To save the new setting, turn ignition switch to OFF and replace fuse.

Alarm modes:Mode 1: If vehicle is seriously damaged and/or door or liftgate is opened while system is armed, thealarm will sound and parking lights will flash for up to 2 minutes.

Mode 2: If door or liftgate is opened while system is armed, the alarm will sound and the parkinglights will flash for up to 2 minutes.

Mode 3: System is always disarmed

Mode 4: If vehicle is damaged and/or someone enters the vehicle while system is armed, an alarmwill sound and the parking lights will flash for up to 2 minutes.Programming ARM/DISARM modes is on next page.

1. Pull fuse No.27 ( MALL PGM ) 10amp from instrument panel fuse block. Turn the ignition switchto ACCESSORY position. Ensure that the seat belt indicator flashes and the chime sounds 2 to 4times. Using other key, turn and hold door lock cylinder to UNLOCK position.2. Depress HORN button on remote keyless entry transmitter to set arming and disarming modes.Each time the button is pressed the mode will advance by one. Seat belt indicator will flash andchime will sound the number of times equal to the current mode setting. A transition past mode 3will bring you back to mode 1. To exit programming and save the current mode, turn ignitionswitch to OFF and replace the fuse.

Arming and disarming modes:Mode 1: System will ARM and DISARM using door lock key or remote transmitter.

Mode 2: System will ARM and DISARM using remote transmitter only (will not disarm with key)

Mode 3: System will ARM when doors are locked from any door lock switch, while any door or liftgateis open and key is removed from ignition switch or while locking doors with key or remote transmitter.The system will disarm using the key or the remote transmitter.

That's great.... where did you get his information from ?

Thanks for all the information, the vehicle was set to arm/disarm using door lock or remote, so I did not have to modify any programming.  Jeff, you are correct, this car will unlock when disarm occurs, I have attempted many relay variations, but no luck.  I have come to the conclusion, once the vehicle is running, press lock once on the remote, the doors will be locked.

Thanks again,

John