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Start/Stop [2021-2022, B420T; B420T2]: Signals

The Engine Control Module (ECM) and the Central Electronic Module (CEM) control the autostart and autostop.

The figure below describes the components used by the function.

GLL1042812Courtesy of VOLVO CARS CORPORATION

The table below summarizes input and output signals, to and from the Engine Control Module (ECM).

Input signals Output signals
Directly connected: 
Accelerator pedal depressed:
  • Sensor, accelerator pedal (7/51)

Neutral gear position detection:
  • Neutral position sensor (7/243) (only manual transmission)

Clutch pedal angle:
  • Clutch pedal angle sensor CPAS (7/309) (only manual transmission)

Reverse gear engaged:
  • Reverse light switch (3/10) (only manual transmission)
 Directly connected: 
Switching connection for the 12 V electrical system and the starter motor to the main battery and the Mid Voltage Battery Module (MVBM):
  • Battery control switch module BCSM (4/153)

Starter motor connection:
  • Fuse box, engine (15/49), includes AR21 soldered starter relay
CAN: 
Autostart request
Main battery status
Ambient temperature
Driver door status
Drive mode
Activation of power sensitive systems:
  • Central Electronic Module (CEM) (4/56) via - Vehicle Computational Unit 1 (VCU1) (4/338)

Drive mode and start/stop function status:
  • Infotainment Head Unit (IHU) (4/185) via

    - Vehicle Computational Unit 1 (VCU1) (4/338)


Driver seatbelt status
Vehicle longitudinal angle:
  • Supplementary Restraint System Module (SRS) (4/176) via

    - Vehicle Computational Unit 1 (VCU1) (4/338


ABS status
Vehicle speed
Brake pressure requested by driver
Acceleration sensor information (to calculate up and downhill slope):
  • Brake Control Module 2 (BCM2) (4/17) via

    - Vehicle Computational Unit 1 (VCU1) (4/338)


Transmission oil temperature
Gear selector position
Information on transmission neutral mode:
  • Transmission Control Module (TCM) (4/28) (only automatic transmission)

Steering angle (autostop is blocked during maneuvering):
  • Steering Wheel Module (SWM) (4/247) including Steering Angle Sensor (SAS)

Battery SoC information (current value and limits)
Battery capacity
Current in/out of the battery
Information about battery faults
Power limits
Battery voltage
Battery relay status
Battery temperature:
  • Mid Voltage Battery Module (MVBM) (4/270)

Electric motor speed, status and temperature
Electric motor voltage and current
Electric motor actual and available torque
Inverter temperature:
  • Integrated Starter Generator Module (ISGM) (4/263)
 CAN: 
Increased power supply status (for determining if the engine is in autostop):
  • Vehicle Computational Unit 1 (VCU1) (4/338) to

    - Central Electronic Module (CEM) (4/56)


Indicator and text message request:
  • Vehicle Computational Unit 1 (VCU1) (4/338) to

    - Driver Information Module (DIM) (5/1)


Increased power supply position status (for determining if the vehicle is in autostop or autostart):
  • Vehicle Computational Unit 1 (VCU1) (4/338) to

    - Infotainment Head Unit (IHU) (4/185)


Request to disengage gear for autostop and engage when autostart is requested:
  • Transmission control module (TCM) (4/28) (only automatic transmission)

Relay position request:
  • Mid Voltage Battery Module (MVBM) (4/270)

Voltage conversion request
Voltage limits
Pre-charge request:
  • Mid Voltage Converter Module (MVCM) (4/265)

Engine speed
Electric motor allowed and requested torque
Electric motor requested voltage:
  • Integrated Starter Generator Module (ISGM) (4/263)

The table below summarizes input and output signals, to and from the Central Electronic Module (CEM).

Input signals Output signals
Directly connected: 
Brake pedal position:
  • Brake pedal sensor (7/308)
  • Clutch pedal angle sensor CPAS (7/309) (only manual transmission)
  
LIN: 
Main battery (1/1) status:
  • Battery Monitoring Sensor (BMS) (4/221)
 LIN: 
Ignition, diagnostic commands:
  • Battery Monitoring Sensor (BMS) (4/221)

Connection and disconnection of main battery and voltage from Mid Voltage Conversion Module (MVCM):
  • Battery control switch module BCSM (4/153)
CAN: 
Risk of mist on windscreen:
  • Humidity sensor (4/229) via

    - Climate Control Module (CCM) (4/154)


Ambient temperature
Driver door status:
  • Driver Door Module (DDM) (4/213)

Trailer connection status (auto stop is blocked if a trailer is connected):
  • Trailer Module (TRM) (4/110)
  
FlexRay: 
Increased power supply position status (for determining whether the vehicle is in auto-stop or auto-start mode):
  • Engine Control Module (ECM) (4/46) via Vehicle Computational Unit 1 (VCU1) (4/338)
 FlexRay: 
Auto-start request
Main battery status
Ambient temperature
Driver door status
Drive mode
Power sensitive systems have been activated:
  • Vehicle Computational Unit 1 (VCU1) (4/338) to

    - Engine Control Module (ECM) (4/46)

Related functions 

The Start/stop function is related to the following functions:

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