2005 Volvo XC90 Base, 4.4 85FACTORY OEM SERVICE PROCEDURE

System Overview: Signals

The table below summarizes input and output signals to and from the Differential Electronic Module (DEM). The illustration below displays the same information with the Volvo component designations.

Input signals Output signals
Directly connected:  Directly connected: 
(power supply unless otherwise stated)
-
  • Electric feed pump  (internal in AOC) - pulse-width modulated (PWM) signal
  • Pressure reducing valve  (internal in AOC) - pulse-width modulated (PWM) signal
Via Controller Area Network (CAN) communication:  Via Controller Area Network (CAN) communication: 
  • central electronic module (CEM)  (4/56), provides the status of, among other things, the ignition position and the back-up (reverse) gear.
  • Brake Control Module (BCM)  (4/16), informs on the speed of the wheels from the wheel speed sensors and ABS modulation status amongst other things.
  • Driver Information Module (DIM)  (5/1), informs on parking brake switch status.
  • Engine Control Module (ECM)  (4/46), informs on engine speed, driver engine torque request, calculated engine torque, accelerator pedal position, stop lamp switch status and clutch pedal switch status, amongst other things.
  • Trailer module (TRM)  (4/110), provides information about whether a trailer is connected to the vehicle or not.
  • Brake control module (BCM)  (4/16), receives information about the status of the coupling unit and current torque capacity for the rear axle.
  • Central Electronic Module (CEM)  (4/56), receives information on the diagnostic status of the Differential Electronic Module (DEM).
  • Driver information module (DIM)  (5/1), via Central electronic module (CEM) receives information about malfunction messages from Differential electronic module (DEM). These are shown to the driver as text messages and warning symbols.
Fig 1: Network Diagram
GLL165533Courtesy of VOLVO CARS CORPORATION
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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.