Alarm goes off Every Time I Open My Door...

[INHWMW]

Hey folks. Got an embarrassment-causing issue I need some help with. Nearly every time I open my door (passenger or driver), regardless of whether I unlocked it or not, the truck's alarm goes off. Very embarrassing in the parking lot at work haha. It's a '96 4.0 Supercab, no key fob or anything. Does anyone know if there's a sensor or something that I can replace to fix this? Or any other possible fixes? I don't know what it is that tells the alarm to go off, so I don't really know where to start here.

Thanks

 

[franklin2]

Do you have a door ajar light on the dash? If you do, is it working?

 

[RobbieD]

And it may help to figure out upfront if it's a factory alarm or an aftermarket alarm.

I take it, that when the "alarm goes off", it's honking the horn, right? Horn can be either; if it's a siren it's aftermarket.

Do you see, or have you noticed, any wiring that doesn't look original? Usual location for such is up under and behind the driver-side dash; and in the engine bay for wires or gizmos that look like they're not factory-installed.

 

[INHWMW]

Yup, door ajar light works. And yes, I meant the horn honking. The “Theft” light on the gauge cluster flashes as it goes off too.

I have crawled around in there before, and didn’t see anything there that I didn’t do. This has only been going on for the last couple weeks, and I’ve owned the truck for years. So it’s rather recent.

 

[RobbieD]

That does sound like a factory-installed alarm. I'm sorry but I don't know that much about trucks after the '94 model year, but there's others here that are knowledgeable, and should be chiming in.

 

[INHWMW]

Anyone else have anything? I’d really appreciate some leads here. Thanks.

 

[franklin2]

What happens when you use the key in the door and unlock it(even if it's already unlocked). Then what happens when you do lock the door, go to work, and then come out and unlock the door?

Sounds like something is arming the alarm, when you do not want it to be armed. I would think if you lock the doors it would arm the alarm, if you did not lock the doors it would not arm the alarm.

 

[franklin2]

Various bits of info from a Chilton manual


Alarm States When Battery Power Is Cycled
When the receiver assembly is powered the very first time at the vehicle assembly plant the system will be in the DISARMED state. The receiver assembly will remember whether it is ARMED, DISARMED or TRIGGERED in its non-volatile memory. When battery power is removed and then reconnected, the system will return to its state just before the battery (10655) was disconnected. If the system is in any PREARM state as described previously, then the system will return to a DISARMED state when battery is disconnected and then reconnected.





Anti-Theft Alarm System
The theft warning system provides the vehicle with protection from unauthorized entry into the passenger compartment and engine compartment (hood opening). It also protects against engine starting through ignition switch tampering. If triggered, the system provides both audio and visual alarm signals and disables the starter circuit.

The system is controlled by a receiver assembly . This assembly also controls the electronic door lock control system functions. System anti-theft functions are:

• Perimeter sensing — doors, trunk, hood
• Ignition tamper sensing
• Starter interrupt
• LED flashing when system is armed
• Perimeter alarm
• Worldwide alarm configurations

For additional information and diagnostic procedures, refer to Remote Control Alarm and Lock System.

When armed, unauthorized entry into the vehicle is detected by a hood switch or the door ajar switches. The hood switch is monitored directly by the receiver assembly. The door ajar switches are monitored by the generic electronic module (see Generic Electronic Module (GEM)). The GEM module signals the receiver assembly when a door is ajar (opened). If the anti-theft system is armed, this signal will trigger the receiver assembly. The door ajar signal will also prevent arming of the system if a door or liftgate is not fully closed.

Once triggered, the system flashes the low beam headlamps (Explorer only), the parking lamps (13200), the alarm indicator, and sounds the horn. In addition, the starter circuit is interrupted until the system is disarmed.

 

[franklin2]

Cancelling the PREARM Sequence
If the anti-theft system is prearmed and waiting, it will wait only 30 minutes for a door to close. The THEFT LED will remain lit for this time. If a door does not close within 30 minutes, the LED will turn off and the theft system will return to a disarmed state.

An anti-theft system PREARM can also be cancelled before the system is armed by:

• pressing the unlock switch on the door
• any disarm event (see Disarming the System)

 

[franklin2]

Disarming the System

NOTE

NOTE: A perimeter alarm will "shut off" after 165 seconds, but the system is still triggered and is not disarmed. The starter circuit will remain disabled until the system is disarmed. An Armed or triggered system can be disarmed by one of the five events listed.

1. Unlock the doors by pressing the remote entry transmitter UNLOCK button once.

1. Unlock the doors by entering the unlock code on the keyless entry keypad.

1. Unlock any door with a key.

1. Turn ignition to RUN or ACCY.

1. The remote entry PANIC button will disarm the anti-theft system only when the perimeter alarm is triggered and sounding.

 

[franklin2]

System Arming

The system is ready to arm any time the ignition switch (11572) is turned OFF and the PANIC alarm is off. There are three ways to PREARM the anti-theft system:

1. Press the remote entry transmitter LOCK button once to lock the doors (with the doors open or closed).

1. Press the 7/8 and 9/0 buttons on the keyless entry keypad at the same time to lock the doors (with the doors open or closed), or

1. Open a door and press the power door lock button to lock the doors.

If a door is open, the anti-theft system is prearmed and waiting for all doors to close. The THEFT LED in the instrument panel (04320) will light continuously while the system is prearmed. Once all doors are closed, if any were open, the system will be prearmed with a 30 second countdown to become armed. The THEFT LED will remain lit continuously until the system is ARMED. When the system is armed, the THEFT LED will begin to flash quickly (blip) for 50 mS every two seconds until the system is triggered or disarmed.

 

[INHWMW]

What happens when you use the key in the door and unlock it(even if it's already unlocked). Then what happens when you do lock the door, go to work, and then come out and unlock the door?

Sounds like something is arming the alarm, when you do not want it to be armed. I would think if you lock the doors it would arm the alarm, if you did not lock the doors it would not arm the alarm.

Thanks for the info there, I’m thinking it might be the door ajar sensor? Or maybe there’s a sensor that tells the truck whether it’s unlocked or not that’s gone bad? I might just need to start taking panels off my door until I find something to try replacing. Anyone know of any sensors that talk to the alarm system?

 

[Uncle Gump]

Disconnect the horn and put a test light across the horn connector when testing.

Does it have an antenna above the inside rear view mirror?

That's s dead giveaway that it has a keyless entry receiver.

I didn't read all... does it have power locks?

 

[INHWMW]

Disconnect the horn and put a test light across the horn connector when testing.

Does it have an antenna above the inside rear view mirror?

That's s dead giveaway that it has a keyless entry receiver.

I didn't read all... does it have power locks?

When testing what? Yes power locks, no keyless entry.

 

[Uncle Gump]

The test light would illuminate opposed to the horn beeping all the time... you know when you're fooling with it.

So no antenna stuck on the inside of the windshield?

Not sure I've encountered a Ranger with an alarm and no keyless entry. Hell... even aftermarket or dealer add on would have a fob to activate it.

It would have to arm with a door lock switch activation and disarm with an door unlock switch activation.

Wish I had a schematic for you... maybe someone else has one to share?