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Home >> Volvo >> 2015 >> XC70 T5 >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Ignition And Control Systems - Design And Function >> Automatic Start/Stop Of Engine >> Automatic Start/Stop Of Engine [2014-2016, B4204T11, TG-81SC] >> System Overview >> Signals
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System Overview: Signals

The tables below summarize the input and output signals to the units in the system for the automatic start/stop of the engine. The signal types are divided into directly connected signals, serial communication and Controller Area Network (CAN) communication.

Engine Control Module (ECM) (4/46) 

Input signals Output signals
Directly connected: 
  • Vacuum pressure sensor (7/251), for registering the air pressure in the brake amplifier.
  • Neutral position sensor (7/243), for registering whether the gear lever is in the neutral position or not. (Only manual gearboxes)
  • Clutch pedal switch B (3/271), for registering whether the pedal is depressed or released. (Only manual gearboxes)
  • Brake light switch (3/9), for determining whether the driver brakes or not in the event of a failed restart of the engine (unintentional engine stall). If the driver does not brake the vehicle, the vehicle starting attempt will be cancelled.
  • Accelerator position sensor (7/51), for autostart of the engine if the driver depresses the accelerator pedal in autostop mode.
 Directly connected: 
  • Battery relay (2/166), for disconnecting the battery (main battery) from the vehicle's other power consumers during autostart after autostop.
  • Secondary battery relay (2/246), for connecting the secondary battery and supplying the vehicle's power consumers during autostart after autostop.
  • Coolant pump relay (2/239), for controlling the extra coolant pump when the engine is in autostop (only cars without additional heaters).
  • Relay starter motor(2/35), for voltage supply to the starter motor.
Via serial communication (LIN): 
  • Alternator (6/26) about the alternator's status.
 Via serial communication (LIN): 
  • Alternator (6/26), for controlling alternator charging.
Via CAN communication: 
  • Central Electronic Module (CEM) (4/56)
    • Clutch pedal switch B (3/39), for registering whether the pedal is depressed or released. (Only manual gearboxes)
    • Secondary battery voltage, for determining the secondary battery's status.
    • The request for activating the secondary battery relay, for charging the secondary battery.
    • Reverse gear status, for blocking the function when stopping or reversing.
    • Alternator charging request. In the event of a fault on the battery monitoring sensor, conventional charging always applies.
    • Status of driver's door, to block the function if the door is open.
  • Brake control module (BCM) (4/16)
    • Status ABS control, to block autostop during ABS control or in the event of a fault on the speed signal.
    • The vehicle speed, for determining when autostop is permitted.
  • Climate Control Module (CCM) (4/6)
    • System requested restart of engine.
  • Supplemental Restraint System Module (SRS) (4/9)
    • Driver safety belt status, for determining whether the driver is using the safety belt.
  • Park brake module (PBM) (4/115)
    • The vehicle's longitudinal angle, to block autostop when forward or backward angle is exceeded.
  • Transmission control module (TCM) (4/28)
    • Blocking start/stop from TCM in reverse or manual position for example.
    • Information stating that the gear selector is in neutral.
    • Status of electric oil pump (EOP).
 Via CAN communication: 
  • Central Electronic Module (CEM) (4/56)
    • Increased power supply position status, for determining whether the vehicle is in autostop or autostart.
  • Driver Information Module (DIM) (5/1)
    • Request for displaying indicators and text messages.
  • Infotainment Control Module (ICM) (3/281) / Infotainment Head Unit (IHU) (4/185)
    • Increased power supply position status, for determining whether the vehicle is in autostop or autostart.
  • Climate Control Module (CCM) (4/6)
    • Increased power supply position status, for determining whether the vehicle is in autostop or autostart.
  • Combustion Preheater Module (CPM) (4/7)
    • Request to start the coolant pump, for circulating coolant to the passenger compartment
  • Power Steering Control Module (PSCM) (6/164)
    • Increased power supply position status, for determining whether the vehicle is in autostop or autostart.
  • Transmission control module (TCM) (4/28)
    • System requested restart of engine due to electric oil pump. (Only automatic gearboxes)

Central Electronic Module (CEM) (4/56) 

Input signals Output signals
Directly connected: 
  • The secondary battery (1/3), for reading off the secondary battery's voltage and thereby for determining the secondary battery's charging requirement.
  • Clutch pedal switch (3/39), for determining when the clutch pedal is depressed. (Only manual gearboxes)
 Directly connected: 
Via CAN communication: 
  • Engine Control Module (ECM) (4/46)
    • Increased power supply position status, for determining whether the vehicle is in autostop or autostart.
  • Climate Control Module (CCM) (4/6)
    • Status of on/off button for automatic start/stop of engine, to disengage or engage the function.
 Via CAN communication: 
  • Engine Control Module (ECM) (4/46)
    • Clutch pedal switch B (3/39), for registering whether the pedal is depressed or released. (Only manual gearboxes)
    • Secondary battery voltage, for determining the secondary battery's status.
    • Secondary battery's average voltage, for determining the secondary battery's status.
    • The request for activating the secondary battery relay, for charging the secondary battery.
    • Outdoor temperature, for calculating whether the function is permitted or not.
    • Status of whether power sensitive power consumers have been activated/connected or not, for controlling brake energy regeneration and alternator.
    • Reverse gear status, for blocking the function when stopping or reversing.
    • Alternator charge request (during conventional charging/faults on the battery monitoring sensor).
  • Climate Control Module (CCM) (4/6)
    • The request to illuminate the LED in the on/off button for automatic start/stop of engine.
Via serial communication (LIN): 
  • Battery monitoring sensor (7/240), with signals about the battery's (main battery) status.
 Via serial communication (LIN): 
  • Battery monitoring sensor (7/240), with signals such as ignition key position and diagnostic commands.

Brake control module (BCM) (4/16) 

Input signals Output signals
Via CAN communication:  Via CAN communication: 
  • Engine Control Module (ECM) (4/46)
    • Status control, to block autostop during ABS control or in the event of a fault on the speed signal.
    • The vehicle speed, for determining when autostop is permitted.

Infotainment Control Module (ICM) (3/281) / Infotainment Head Unit (IHU) (4/185) 

Input signals Output signals
Via CAN communication: 
  • Engine Control Module (ECM) (4/46)
    • Increased power supply position status, for determining whether the vehicle is in autostop or autostart.
 Via CAN communication: 

Climate Control Module (CCM) 

Input signals Output signals
Via CAN communication: 
  • Engine Control Module (ECM) (4/46)
    • Increased power supply position status, for determining whether the vehicle is in autostop or autostart.
  • Central Electronic Module (CEM) (4/56)
    • The request to illuminate the LED in the on/off button for automatic start/stop of engine.
 Via CAN communication: 
  • Central Electronic Module (CEM) (4/56)
    • Status of on/off button for automatic start/stop of engine, to disengage or engage the function.
  • Engine Control Module (ECM) (4/46)
    • System requested restart of engine.

Driver Information Module (DIM) (5/1) 

Input signals Output signals
Via CAN communication: 
  • Engine Control Module (ECM) (4/46)
    • Request for displaying indicators and text messages.
 Via CAN communication: 

Supplemental restraint system module (SRS) (4/9) 

Input signals Output signals
Via CAN communication:  Via CAN communication: 
  • Engine Control Module (ECM) (4/46)
    • Driver safety belt status, for determining whether the driver is using the safety belt.

Combustion Preheater Module (CPM) (4/7) 

Input signals Output signals
Via CAN communication: 
  • Engine Control Module (ECM) (4/46)
    • Request to start the coolant pump, for circulating coolant to the passenger compartment.
 Via CAN communication: 

Power Steering Control Module (PSCM) (6/164) 

Input signals Output signals
Via CAN communication: 
  • Engine Control Module (ECM) (4/46)
    • Increased power supply position status, for determining whether the vehicle is in autostop or autostart.
 Via CAN communication: 

Park brake module (PBM) (4/115) 

Input signals Output signals
Via CAN communication:  Via CAN communication: 
  • Engine Control Module (ECM) (4/46)
    • Signal about the vehicle's longitudinal inclination.
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