The chart below summarizes the input signals to and output signals from the different control modules for the alarm function. The signal types are divided into directly connected signals, serial communication and control area network (CAN) communication.

Directly connected input signals from the sensors / switches to the control module:	Directly connected output signals to the controlled components / functions from the control module:
Central electronic module (CEM) (4/56) All doors, closed/open Rear doors, locked/unlocked Tailgate, closed / open Hood, closed/open Resistive wire, broken/unbroken (only V70/V70XC).	Central electronic module (CEM) (4/56) The turn signal lamps, on/off Alarm diode (3/112), on/off. (via the climate control module (CCM).
The climate control module (3/112) Switch for reduced alarm, on/off.	The climate control module (3/112) Alarm diode, on/off. Direct cable from the central electronic module through the climate control module.
The driver's door module (3/126) Driver's door, locked/unlocked Key, locking / neutral position/ unlocking.
The passenger door module (3/127) The passenger door, locked/unlocked.

Received information to control modules via Controller Area Network (CAN):

Transmitted information to control modules via Controller Area Network (CAN):

The central electronic module (4/56) receives from:
The climate control module (3/112)

Switch for reduced alarm, on/off.

Driver's door module (DDM) (3/126)

Driver's door, locked/unlocked
Key, locking / unlocking.

Passenger door module (3/127)

Passenger door, locked/unlocked.

Rear electronic module (4/58)

Vehicle inclination sensor status from the inclination sensor module.

Upper electronic module (4/70)

Button status from the remote control, LOCK/ UNLOCK
Battery status siren
The status of the Mass movement sensor.

The central electronic module (4/56) transmits to:
The driver information module (5/1)

Text message in the text window.

Driver information module (5/1) receives from:
The central electronic module (CEM) (4/56)

Text message.

The upper electronic module (4/70) transmits to:
The central electronic module (CEM) (4/56)

Remote control signal. LOCK, UNLOCK, BOOT
The status of the Mass movement sensor
Battery status siren.

Received information to control modules via serial communication:

Transmitted information to control modules via serial communication:

The rear electronic module (4/58) receives from:
Inclination sensor module (7/100)

Vehicle inclination sensor status.

The upper electronic module (4/70) transmits to:
Siren control module (16/35)

Activate/deactivate the siren
The mass movement sensor (7/122), on/off.

The upper electronic module (4/70) receives from:
The mass movement sensor (7/122)

Movement in the passenger compartment.

Siren control module (16/35)

Battery status.

Rear electronic module (4/58) transmits to:
Inclination sensor module (7/100), on/off.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Alarm (2001-2004): Signals

Use the Manual With the Right Hardware

When to See a Mechanic

Rather have a pro handle this?