Honda 2004 Odyssey Service Manual page 1935

Power Door Locks/Factory Keyless/Factory Security
System Description
Security Alarm System
NOTE: For a description of the security system on '99-04 LX or '99-00 EX models, refer to the ETM and accessory alarm
owner's manual.
The security alarm system is armed automatically after the doors, hood, and tailgate are closed and locked. For the
system to arm, the ignition switch must be off, the key must be removed, and the security control unit must receive
signals that the doors, hood, and tailgate are closed and locked. The alarm can be disarmed at any time by unlocking
either door with the key or the remote transmitter.
When everything is closed and locked, the only control unit inputs that are grounded, and have 0 volts, are the driver's
door lock knob switch, the audio unit, and the navigation display. In other words, all of the other switches are open,
including the key cylinder switches, and they have about 10 volts. Ten seconds after the doors are locked with the key
or the lock knob (with the door open), or immediately after the doors are locked with the LOCK button on the remote
transmitter, the security system arms, and the security indicator on the gauge flashes. If the security indicator does not
flash, the system is not arming. Check the doors, hood, and trunk to see if they are closed. A beep to confirm the
security alarm system is armed will sound if the LOCK button is pressed a second time within 5 seconds.
If one of the switches is misadjusted or there is a short in the system, the system will not arm. As long as the control
unit continues to receive a ground signal, it senses that the vehicle is not closed and locked, and the system will not
arm. Conversely, a switch that is slightly misadjusted can sound an alarm for no apparent reason. In this case, a
significant change in outside temperature, the vibration of a passing truck, or someone bumping into the vehicle could
cause the alarm to sound. There is no glass breakage or motion detector feature.
If anything is opened or improperly unlocked after the system is armed, the control unit receives a ground signal from
that switch, and the 10 volts reference drops to 0 volts. If the radio is disconnected, the input loses its ground, and the
input voltage goes to 10 volts. The system sounds the alarm when any of these things occur:
• A door is forced open
• A door is unlocked without using the key or the remote transmitter
• The hood is opened
• The tailgate is opened without using the transmitter
• The audio unit, navigation display unit, DVD player unit, or rear controller and screen is disconnected
• The panic mode is activated
When the system sounds the alarm, the security horn sounds and the exterior lights flash for 2 minutes. The alarm can
be stopped at any time by unlocking either door with the key or by pushing any button on the remote transmitter.
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-'01-04 EX, EXL