Alarm in my 2002 gmc Sonoma goes off when I open the door with the key. Lost remote. Can I disable the alarm without messing other things up?
Door Key Switch
The BCM monitors the door key switches in order to disarm the CTD system. When the lock cylinder turns in order to unlock the door, the switch grounds the disarm input to the BCM.
The key lock input to the BCM is probably missing , BCM doesn't see it . So it think's your breaking into the vehicle. Did you try the passenger door to see if it will disable the alarm .
The BCM - body control module ! Electronic -computer !
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Content Theft Deterrent (CTD) Does Not Disarm with Key Lock
The factory service repair manual has a 23 step diagnostic procedure . An you would need a factory scan tool to find the correct fix.
Turn ON the ignition with the engine OFF.
With a scan tool, observe the door key switch parameter in the Body Control Module (BCM) security data list.
Does the scan tool display INACTIVE?
Locking the Vehicle Without Arming the System
Use one of the following procedures in order to lock the vehicle without arming the system:
• Procedure A -- Lock the vehicle using the manual door lock knobs. Close all the doors.
• Procedure B -- Close all the doors. Use the key or the power door lock switch in order to lock the door. The doors must be closed prior to locking the doors for this procedure.
Disarming the System
In the arm initiated mode, the following conditions are true:
• The security telltale is ON.
• The doors are open.
In order to disarm a system in the arm initiated mode, perform one of the following procedures:
• Press the power door lock switch to the UNLOCK position.
• Press the door unlock button on the key fob.
In order to disarm a system in the arm delay or the armed mode, perform one of the following procedures:
• Use the key in order to unlock one of the doors.
• Press the door unlock button on the key fob.
Deactivating the Alarm
In the alarm mode, the following conditions are true:
• The horns sound intermittently.
• The headlights and the park lamps are flashing.
In order to deactivate a system in the alarm mode, perform one of the following procedures:
• Use the key in order to unlock one of the doors.
• Press the door unlock button on the key fob.
• If the vehicle control module (VCM)/powertrain control module (PCM) receives a valid Passlock™ ignition key rotation.
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