Reset alarm module?

CRAZYDOGS225

MEMBER
1993 FORD EXPLORER
4.0L
V6
4WD
AUTOMATIC
130,000 MILES

The vehicle listed above is a Limited model with factory alarm. My alarm module drowned when I was washing my car (common problem with this model and others - covered by a TSB). The headlights and flashers and horn all going, wouldn't stop by pressing unlock on key fob or inserting my original Ford key in the ignition.
I disconnected the neg battery and waited. After a couple of hours, I reconnected the negative battery and the alarm went off again (pulled neg battery again).
After trying numerous troubleshooting fixes, I unplugged the connector on the "alarm" side of the alarm module so I could drive it (my keyless remote still works for doors and panic, but no alarm function or starter immobilizer).
After a week, I disconnected the negative battery, re-plugged in the connector, reconnected the neg battery terminal and the alarm went off (flashing headlights, flashers and horn). Didn't stop when I pressed unlock on remote or inserted my ignition key, but I was able to start and drive the car with lights flashing and horn blowing (which confuses me).
Any suggestions? I can drive it with the alarm connector pulled but I'd really like to have the alarm functions again.

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
42,913 POSTS

It sounds like the alarm module has gone out which is common but lets go over this guide and information to be sure:

In 1993 Ford Explorers, the factory-installed security system typically did not have an alarm module that could be reset in the same way that modern vehicles do. However, there were some security features in place that might lead to concerns or issues related to starting the vehicle.

If you're experiencing issues with your 1993 Ford Explorer related to the security system or anti-theft features, here are some general steps you can take:

Verify the Key: If the vehicle isn't starting and you suspect a security issue, ensure that you're using the correct key. Vehicles of that era often used a physical key with a transponder chip or a passive anti-theft system (PATS). Using an incorrect key or a duplicate that doesn't have the proper transponder can lead to starting problems.

Check for Warning Lights: If the security system is causing issues, there might be warning lights on the dashboard indicating a security-related problem. Pay attention to any symbols or lights that are illuminated when you try to start the vehicle.

Battery Check: Make sure the vehicle's battery is in good condition. Low battery voltage can sometimes trigger security system issues. Check for corrosion on the battery terminals as well.

Try a Different Key: If you have multiple keys for the vehicle, try using a different one to see if the issue persists.

Disconnect and Reconnect the Battery: In some cases, disconnecting the vehicle's battery for a few minutes and then reconnecting it can reset certain systems, including security-related ones. However, be cautious as this might also reset other settings.

DESCRIPTION
When triggered, the anti-theft system honks the horn and flashes the lo beam headlamps and park lamps at an intermittent rate of approximately 80 cycles per minute. In addition, the starting system is disabled until the system is disarmed.

OPERATION

Arming the System
The system is ready to arm any time the ignition switch is turned to the "OFF" position and a door is opened. Voltage to the anti-theft controller module, 296 (W/P) wire, is removed when the ignition switch is in "OFF". Opening a door closes the door courtesy lamp switch in that door, applying 12 volts to the "Courtesy Lamp Input" of the module through the 24 (DB/O) and 627 (BK/O) wires. This causes the module to apply a pulsating ground signal through the 343 (DB/LG) wire to flash the anti-theft indicator Lamp.

With the ignition switch in "OFF" and a door open, locking the doors with the power door lock switch or depressing the last two remote keyless entry buttons begins the arming sequence. Either of these actions applies voltage to the module on the 117 (PK/BK) wire. The indicator Lamp will now glow steadily.

System arming can be cancelled before all doors are closed by unlocking the door with the power door lock switch or by using the remote keyless entry "UNLOCK" code. Either of these actions applies voltage to the module through the 118 (PK/O) wire to cancel arming. The alarm indicator will start flashing again. Turning the ignition switch to "ACC" or "RUN" will also cancel arming by applying voltage to the module on the 296 (W/P) wire.

The arming cycle is completed by closing all doors. Approximately thirty seconds after the last door is closed, the indicator lamp turns "OFF", indicating that the arming cycle is complete.

Triggering the System
Opening any door without disarming the system triggers the alarm (lamps and horn) for three minutes, even if the door closes. After three minutes, the lamps and horn will turn off and the module will return to an armed state. Also, the starting system is disabled and will remain disabled until the system is disarmed.

Once the system is armed, opening any door provides 12 volts through the 24 (DB/O) wire to trigger the alarm circuits in the module. The module then provides a pulsating ground signal to the alarm Indicator through the 343 (DB/LG) wire and to the horn relay coil through the 6 (V/LG) wire. Pulsating battery voltage is applied to the lo beam headlamps through the 13 (R/BK) wire and to the park lamps through the 14 (BR) wire.

At the same time, the module prevents current from energizing the starter relay by means of an open circuit between wires 33 (W/PK) and 32 (R/LB); the car cannot be started.

An anti-theft hood switch is also included in the system. If an attempt is made to open the hood while the system is armed, the switch closes and a ground signal is applied to the module through the 23 (T/LG) wire. This triggers the system in the same manner as previously described for opening a door. The liftgate key can be used to open the liftgate without triggering the system.

Disarming the System
To disarm the system, a front door can be unlocked with the key, or the remote keyless entry "UNLOCK" code can be used.

Unlocking a front door with the key provides a ground path through an anti-theft disarm switch and the 25 (DG/P) wire to the module. This ground signal disarms the system.

If the driver arms the system and remains in the car (all doors closed), the system can be disarmed by inserting the key in the ignition switch and turning the switch to "ACC" or "RUN". The battery voltage applied to the module on the 296 (W/P) wire disarms the system.

Please go over these guides and get back to us.