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Toyota 4Runner 1984-2002: Why Does My Alarm Keep Going Off?

Repair a faulty vehicle alarm in your Toyota 4Runner using these straightforward tips, and save yourself a lot of aggravation in the process.

By Charlie Gaston - January 21, 2016

This article applies to the Toyota 4Runner (1984-2002).

A faulty factory or aftermarket alarm can be one of the most bothersome problems you face as a (1984-2002) Toyota Tacoma owner. But that doesn't mean you have to put up with it; at least not for long. Thanks to some pretty straightforward do-it-yourself tips and troubleshooting advice, you can fix a malfunctioning factory or aftermarket alarm on your own. This guide will walk you through the things you'll need to look for as well as explain what you should do once those problem areas have been diagnosed.

Toyota 4Runner Why is My Alarm Going Off infographic

Materials Needed

  • Replacement battery
  • Voltmeter

Step 1 – Change the alarm mode

It might be in "valet" mode.

If you've recently disconnected and then reconnected your battery, it's highly likely you triggered your alarm to automatically enter into "valet" mode (versus "keyless entry") when your doors open.

  • Check beneath the dashboard for a toggle switch.
    • Find the toggle switch underneath your dashboard
    Figure 1. Find the toggle switch underneath your dashboard.
  • Use the switch to exit out of "valet" mode and back into "keyless entry" mode.
  • This is a simple fix that should not require the help of a mechanic. If it does, expect to pay very little for the repair (if anything at all, depending on your relationship with the mechanic).
  • You will see a blinking light whenever your alarm is activated.
Do you see a light indicating your alarm is active?
Figure 2. Do you see a light indicating your alarm is active?

Pro Tip

If you have a factory alarm, you may be able to disable it by placing your key in the door, and then locking and unlocking it.

Step 2 – Check the battery

It might be on its last leg.

If the voltage is too low in your battery, you may notice that your alarm is triggered every time you attempt to start your car.

  • The problem occurs because your car can not crank up properly; thereby, causing your alarm to sound.
  • Low battery voltage and cold weather can both cause this problem to occur; however, a bad battery is the most common culprit.
  • Read the level of voltage in your battery using a quality voltmeter.
  • Change your battery if the voltage is too low; otherwise, your alarm will continue to sound.
  • This repair should cost you around $100-$150, depending on the cost to replace your old battery.
Disconnect the negative connector first, followed by the positive one
Figure 3. Disconnect the negative connector first, followed by the positive one.

Step 3 – Check the alarm

It might have a bad sensor or other malfunctioning component.

The wiring in your alarm could be bad, causing it to go off randomly. It will need to be carefully checked for damage and looseness.

  • Inspect the wiring for a loose connection or poor grounding.
  • As well, check for a bad shock sensor.
  • It's also recommended that you check that the shock sensor is not adjusted too high, which would make it highly temperamental.
This is a generic example of a bad ground
Figure 4. This is a generic example of a bad ground.

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