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Ask Hammer Time Your Own Question

Hammer Time
Hammer Time, L1 Master Technician
Category: Car
Satisfied Customers: 4942
Experience:  ASE Mastertech with Adv level Engine performance cert.
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disable my factory alarm on my 1998 jeep grand cherokee

Customer Question

How do i disable a factory alarm on a 1998 jeep grand cherokee?
Submitted: 8 years ago.
Category: Car
Expert:  Hammer Time replied 8 years ago.

Can't be done. The security features are written right into the operating software and cannot be disabled or defeated. That's why they call it security.


If your having a problem with the system, you will have to repair it. I know that's not what you want to hear but don't shoot the messenger.

Customer: replied 8 years ago.
Reply to Hammer Time's Post: I have read about people disconnecting the underhood switch and it shut down the alarm.
Customer: replied 8 years ago.
Reply to Hammer Time's Post: How do i repair it then?
Expert:  Hammer Time replied 8 years ago.

All you can do is have the dealer diagnose it using the factory scan tool. You really can't determine anything without that equipment.


here's some explanation on how the system works.








INTRODUCTION
The Vehicle Theft Security System (VTSS) is an available factory-installed option on this model. This system is designed to provide perimeter protection against unauthorized use or tampering by monitoring the vehicle doors, liftgate, and ignition system. If unauthorized use or tampering is detected, the system responds by sounding the horn, flashing the exterior lamps, and providing an engine no-run feature. The VTSS can be disarmed by unlocking the vehicle with the key in either front door lock cylinder or using the Remote Keyless Entry (RKE) transmitters.

Following are some general descriptions of the features of the VTSS. Refer to the vehicle owner's manual for additional information on the use and operation of this system.

Enabling
The Vehicle Theft Security System (VTSS) features are provided by two electronic modules in the vehicle; the Powertrain Control Module (PCM) located in the engine compartment, and the Body Control Module (BCM) located in the passenger compartment. Both of these modules must have their respective VTSS functions electronically enabled in order for the VTSS to perform as designed.

The VTSS engine no-run feature is disabled when it is shipped from the factory. This is done by programming within the Powertrain Control Module (PCM). The logic in the PCM prevents the VTSS engine no-run feature from arming until the engine start counter within the PCM sees twenty engine starts. The VTSS no-run feature must be enabled when the vehicle is received from the assembly plant.

The preferred method for enabling the VTSS engine no-run feature is to electronically advance the PCM engine start counter using a DRB scan tool. Refer to the Vehicle Theft Security System menu item on the DRB scan tool for the procedures. Once this condition has been met, the PCM will allow the engine no-run feature to arm. Once the VTSS engine no-run feature has been enabled in the PCM, it cannot be disabled. The same VTSS engine no-run feature enable logic will apply anytime the PCM is replaced with a new unit.

The remaining VTSS features are controlled by the BCM. The logic in the BCM keeps its VTSS features dormant until it is enabled using a DRB scan tool. The VTSS features of the BCM are enabled on vehicles equipped with the VTSS option at the factory, but a service replacement BCM must be enabled by the dealer with a DRB scan tool anytime the BCM is replaced with a new unit.

Arming
Passive arming of the Vehicle Theft Security System (VTSS) occurs when the vehicle is exited with the key removed from the ignition switch, the head-lamps are turned off, and the doors are locked using the power lock switch. The power lock switch will not function if the key is in the ignition switch or the headlamps are on with the driver side front door open. The VTSS will not arm if either front door or the liftgate are locked using the key in the lock cylinder or using the mechanical lock button.

Active arming of the VTSS occurs when the Remote Keyless Entry (RKE) transmitter is used to lock the vehicle, even if the doors and/or the liftgate are open when the RKE transmitter Lock button is depressed. However, the VTSS arming will not be complete until all of the doors and the liftgate are closed.

Following successful passive or active VTSS arming, the VTSS set lamp on the top of the instrument panel will flash rapidly for about fifteen seconds after the illuminated entry system times out. This indicates that VTSS arming is in progress. Once the fifteen second arming function is successfully completed, the set lamp will flash at a slower rate to indicate that the VTSS is armed.

Disarming
Passive disarming of the Vehicle Theft Security System (VTSS) occurs when the vehicle is unlocked using the key to unlock either front door or the lift-gate. Active disarming of the VTSS occurs when the vehicle is unlocked by depressing the Unlock button of the Remote Keyless Entry (RKE) transmitter.

Once the alarm has been activated (horn sounding, exterior lamps flashing, and the engine no-run feature), either disarming method will also deactivate the alarm.

Depressing the Panic button on the RKE transmitter will also disarm the VTSS, but the horn will sound and the exterior lamps will flash for about three minutes as part of the Panic feature function. Refer to Body and Frame/Locks/Power Locks Systems for more information on the Panic feature.

Power-Up Mode
When the armed Vehicle Theft Security System (VTSS) senses that the battery has been disconnected and reconnected, it enters its power-up mode. In the power-up mode the alarm system remains armed following a battery failure or disconnect. If the VTSS was armed prior to a battery disconnect or failure, the system will have to be actively or passively disarmed after the battery is reconnected.

The power-up mode will also apply if the battery goes dead while the system is armed, and battery jump-starting is attempted. The engine no-run feature will prevent the engine from starting until the alarm system has been actively or passively disarmed.

Tamper Alert
The Vehicle Theft Security System (VTSS) tamper alert will sound the horn three times upon disarming, if the alarm was activated and has since timed-out (about eighteen minutes). This feature alerts the vehicle operator that the VTSS was activated while the vehicle was unattended.

SYSTEM OPERATION
Body Control Module
A Body Control Module (BCM) is used on this model to control and integrate many of the electronic functions and features included on the vehicle. The BCM contains a central processing unit and interfaces with other modules in the vehicle on the Chrysler Collision Detection (CCD) data bus network.

The CCD data bus network allows the sharing of sensor information. This helps to reduce wire harness complexity, reduce internal controller hardware, and reduce component sensor current loads. At the same time, this system provides increased reliability, enhanced diagnostics, and allows the addition of many new feature capabilities.

One of the functions and features that the BCM supports and controls, is the Vehicle Theft Security System (VTSS). In the VTSS, the BCM receives CCD message inputs from the Passenger Door Module (PDM), which contains the Remote Keyless Entry (RKE) receiver. In addition to the information received on the CCD data bus, the BCM receives hard-wired inputs from the door ajar, door lock cylinder, ignition, liftgate ajar, liftgate lock cylinder, and liftglass ajar switches. The programming in the BCM allows it to process the information from all of its inputs and send control outputs to energize or de-energize the auto headlamp relay, horn relay, park lamp relay, Powertrain Control Module (PCM), and the security set lamp.

The BCM is mounted under the driver side outboard end of the instrument panel, behind the instrument panel support armature and below the outboard switch pod. Refer to Instrument Panel, Gauges and Warning Indicators/Instrument Panel Systems for the removal and installation procedures. For diagnosis of the BCM or the CCD data bus, the use of a DRB scan tool and the proper Diagnostic Procedures are recommended. The BCM can only be serviced by an authorized electronic repair station. Refer to the latest Warranty Policies and Procedures for a current listing of authorized electronic repair stations.

Door Ajar Switch
The door ajar switches are mounted to the pillar in the rear of each door opening. They are plunger-type switches that are case grounded to the pillar. When the door is open the switch is closed, and when the door is closed the switch is open.

The door ajar switches cannot be repaired and, if faulty or damaged, they must be replaced.

Door Lock Cylinder Switch
The door lock cylinder switches are mounted to the back of the key lock cylinder inside each front door. They are normally-open momentary switches that close to ground only when the lock cylinder is rotated to the unlock position.

The door lock cylinder switches cannot be repaired and, if faulty or damaged, they must be replaced.

Liftgate Ajar Switch
The liftgate ajar switch is integral to the liftgate latch assembly on the liftgate. It is a momentary-type switch that is open when the liftgate is closed, and closed when the liftgate is open.

The liftgate ajar switch cannot be repaired and, if faulty or damaged, the liftgate latch assembly must be replaced.

Liftgate Lock Cylinder Switch
The liftgate lock cylinder switch is mounted to the back of the key lock cylinder inside the liftgate. It is a normally-open momentary switch that closes to ground only when the lock cylinder is rotated to the unlock position.

The liftgate lock cylinder switch cannot be repaired and, if faulty or damaged, it must be replaced.

Liftglass Ajar Switch
The liftglass ajar switch is integral to the liftglass latch assembly on the liftgate. It is a momentary-type switch that is open when the liftglass is closed, and closed when the liftglass is open.

The liftglass ajar switch cannot be repaired and, if faulty or damaged, the liftglass latch assembly must be replaced.

Auto Headlamp Relay
The auto headlamp relay is a International Standards Organization (ISO) micro-relay. The terminal designations and functions are the same as a conventional ISO relay. However, the micro-relay terminal orientation (or footprint) is different, current capacity is lower, and the relay case dimensions are smaller than those of the conventional ISO relay.

The auto headlamp relay is a electromechanical device that switches battery current to the head-lamps when the Body Control Module (BCM) grounds the relay coil. See the Diagnosis and Testing for more information on the operation of the auto headlamp relay.

The auto headlamp relay is located in the junction block, on the right cowl side inner panel below the instrument panel in the passenger compartment.

The auto headlamp relay cannot be repaired and, if faulty or damaged, it must be replaced.

Horn Relay
The horn relay is a International Standards Organization (ISO) micro-relay. The terminal designations and functions are the same as a conventional ISO relay. However, the micro-relay terminal orientation (or footprint) is different, current capacity is lower, and the relay case dimensions are smaller than those of the conventional ISO relay.

The horn relay is a electromechanical device that switches battery current to the horn when the horn switch or the Body Control Module (BCM) grounds the relay coil. See the Diagnosis and Testing for more information on the operation of the horn relay.

The horn relay is located in the Power Distribution Center (PDC), in the engine compartment. Refer to the PDC label for relay identification and location.

If a problem is encountered with a continuously sounding horn, it can usually be quickly resolved by removing the horn relay from PDC until further diagnosis is completed.

The horn relay cannot be repaired and, if faulty or damaged, it must be replaced.

Park Lamp Relay
The park lamp relay is a International Standards Organization (ISO) micro-relay. The terminal designations and functions are the same as a conventional ISO relay However, the micro-relay terminal orientation (or footprint) is different, current capacity is lower, and the relay case dimensions are smaller than those of the conventional ISO relay.

The park lamp relay is a electromechanical device that switches battery current to the park lamps when the Body Control Module (BCM) grounds the relay coil. See the Diagnosis and Testing for more information on the operation of the park lamp relay.

The park lamp relay is located in the junction block, on the right cowl side panel below the instrument panel in the passenger compartment. The park lamp relay can be accessed by removing the fuse access panel and the right cowl side trim panel.

The park lamp relay cannot be repaired and, if faulty or damaged, it must be replaced.

Set Lamp
The Vehicle Theft Security System (VTSS) set lamp is a red light-emitting diode mounted with the auto headlamp ambient light sensor on top of the instrument panel near the driver side defroster outlet. The set lamp receives fused battery feed at all times and is grounded by the Body Control Module (BCM) to give a visual indication of the VTSS status.

The set lamp cannot be repaired and, if damaged or faulty, the set lamp/auto headlamp ambient light sensor unit must be replaced.












































































































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