Dodge Ram 1500 Problem: Horn Chirp and Erroneous Alarm

Hi, this article will provide a diagnosis and solution regarding horn chirp and erroneous alarm (alarm siren) when you open the truck door. It is related to electrical parts, especially on 2002-2003 Dodge Ram.

Alarm problems can be very annoying for truck owners and you may face other issues like code P0700, and sometimes they don’t know what’s causing it.

Two Possible Conditions That Cause Horn Chirp and Erroneous Alarm Problems On Dodge Ram 1500

Electronic connection issues involving the Forward Controller Module (FCM) with various electronic modules inside the truck have been shown to correlate to two scenarios.

The 1st scenario can happen when a truck has completely switched off and left for longer than 3 minutes. You can hear the horn chirping whenever a door opens, which is relatively short.

The electrical components work or remain active for 2 – 3 minutes after the engine shuts off.

The modules disengage or enter into a sleep state following 2 – 3 minutes of idleness. The units are triggered or awakened whenever a door is left open.

So when modules start waking up because once the door opens, you may hear a quick horn chirp. A connection fault throughout the FCM could cause problems.

The 2nd scenario occurs when a car without a Vehicle Theft Security System (VTSS) generates an alarm, including the active horn and lights flashing.

Connectivity issues with the FCM might potentially trigger problems.

Each of mentioned issues has been resolved thanks to FCM program updates. The circumstances can be corrected by resetting the FCM using the most recent software version.

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Understanding Accessory Relay

The accessory relay in your Dodge Ram controls several parts like the radios, electric windows, motor for washing pumps, windshield, and electrical ports in combination with the FCM’s power accessories delay functions.

Your truck FCM activates the accessory relay via the relay’s lower side controller circuit. This connection is electrically regulated, and problems are constantly checked.

The accessory relay would either stay on or break and disengage based on the area of the ignition system.

In RUN or ACCY ignition control settings, the auxiliary relay stays engaged.

The relay would stay powered for approximately 45 secs within UNLK or Off settings before deactivating.

Whenever a driver or passenger side door is started to open throughout the break time, the relay would lose power instantly.

The relay will idle and restart working when the ignition has been at the Start point. The working of the accessory relay is often noticeable when the radio works.

How to Diagnose Alarm Problems On Dodge Ram 1500

Assuming one of the abovementioned circumstances occurs to your truck, you must conduct the Repair Process and reconfigure your Front Controller Module (FCM).

Procedure for Repairing Alarm Problems on Dodge Ram 1500

  1. Attach your battery charger, then adjust the voltage as close to 14 volts.
  2. Here you need to be knowledgeable about using a scan tool for your truck. Then by using a scan tool such as DRBIII(R) and Mopar Diagnostic System (MDS2), you need to Flash reprogram your FCM or Front Controller Module. However, you need to use software version 5.4 or later.
  3. Re-check the condition of your truck and make sure the Horn Chirp and Erroneous Alarm problems are no longer there.
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Thus the article on how to solve the alarm problem on your Dodge Ram 1500, hopefully, can be useful for you.

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