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Principles of Operation: HS-Can

WARNING: This page is about a different car, the 2008 Mercury Milan, 2008 Lincoln MKZ, and 2008 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

The HS-CAN is a high speed communication network that uses an unshielded twisted pair cable of data (+) and data (-) circuits. The data (+) and the data (-) circuits are each regulated to approximately 2.5 volts during neutral or rested network traffic. As bus messages are sent on the data (+) circuit, voltage is increased by approximately 1.0 volt. Inversely, the data (-) circuit is reduced by approximately 1.0 volt when a bus message is sent. Multiple bus messages can be sent over the network CAN circuits allowing multiple modules to communicate with each other. The HS-CAN will not communicate while certain faults are present, but will operate with diminished performance with other faults present. The HS-CAN bus may remain operational when 1 of the 2 termination resistors are not present.

The HS-CAN operates at a maximum data transfer speed of 500 Kbps and is designed for real time information transfer and control. The network will remain operational, but at a degraded level when certain circuit faults are present. The HS-CAN may remain operational with only one termination resistor present.

The following modules are on the HS-CAN:

The following fault chart describes the specific HS-CAN failures and their resulting symptom:

HS-CAN COMMUNICATION FAULT CHART

Failure Description Symptom
HS-CAN (+) shorted to HS-CAN (-) No communication
HS-CAN (+) short to voltage No communication
HS-CAN (-) short to voltage No communication
HS-CAN (+) short to ground No communication
HS-CAN (-) short to ground Unreliable communication possible in all network modules
HS-CAN (+) open Unreliable communication possible in all network modules
HS-CAN (-) open Unreliable communication possible in all network modules
Module loss of voltage or ground No communication
Module internal failure No communication
NOTE: This chart describes the specific high speed controller area network (HS-CAN) and medium speed controller area network (MS-CAN) messages broadcast by each module, and the module(s) that receive the message.
CAN MODULE COMMUNICATION MESSAGE CHART

Broadcast Message Originating Module Network Type Receiving Module(s)
ABS event in progress ABS module HS-CAN
  • PCM
  • Restraints control module (RCM)
  • Transmission control module (TCM)
ABS/TRAC system configuration ABS module HS-CAN
  • TCM
ABS malfunction indicator request ABS module HS-CAN
  • Instrument cluster (IC)
A/C clutch inhibit request TCM HS-CAN
  • PCM
A/C clutch request Heating ventilation air conditioning (HVAC) module MS-CAN
  • IC
A/C clutch request (gateway) IC HS-CAN
  • PCM
A/C clutch status PCM HS-CAN
  • IC
A/C clutch status (gateway) IC MS-CAN
  • HVAC module
A/C evaporator temperature PCM HS-CAN
  • IC
A/C evaporator temperature (gateway) IC MS-CAN
  • HVAC module
Accelerator pedal position PCM HS-CAN
  • ABS module
  • RCM
  • TCM
  • 4X4 control module
Accessory delay status Smart junction box (SJB) MS-CAN
  • Audio control module (ACM)
Airbag deployment event status RCM HS-CAN
  • Occupant classification system module (OCSM)
  • PCM
Airbag malfunction indicator request RCM HS-CAN
  • IC
AWD active indicator request 4X4 control module HS-CAN
  • IC
AWD coupling mode and status 4X4 control module HS-CAN
  • ABS module
  • IC
AWD malfunction indicator request 4X4 control module HS-CAN
  • IC
Axle ratio PCM HS-CAN
  • ABS module
Barometric pressure PCM HS-CAN
  • IC
  • TCM
Barometric pressure (gateway) IC MS-CAN
  • SJB
Battery saver status SJB MS-CAN
  • IC
Brake fluid level status SJB MS-CAN
  • IC
Brake malfunction indicator request ABS module HS-CAN
  • IC
Brake switch status PCM HS-CAN
  • RCM
  • TCM
  • 4X4 control module
Charging system warning indicator request PCM HS-CAN
  • IC
Charging system status PCM HS-CAN
  • IC
Climate control seat setting HVAC module MS-CAN
  • Dual climate control seat module (DCSM)
Climate control seat status DCSM MS-CAN
  • HVAC module
Door ajar status SJB MS-CAN
  • IC
Door lock command (w/memory) SJB MS-CAN
  • Driver door module (DDM)
Door lock switch status, driver (w/memory) DDM MS-CAN
  • SJB
Easy entry/exit command IC MS-CAN
  • Driver seat module (DSM)
Easy entry/exit status DSM MS-CAN
  • IC
Engine coolant temperature PCM HS-CAN
  • IC
  • TCM
  • 4X4 control module
Engine coolant temperature (gateway) IC MS-CAN
  • HVAC module
Engine cooling fan request TCM HS-CAN
  • PCM
Engine fail-safe cooling mode status PCM HS-CAN
  • IC
  • TCM
Engine fail-safe electronic throttle control (ETC) mode status PCM HS-CAN
  • IC
Engine fuel consumption data PCM HS-CAN
  • IC
Engine intake air temperature PCM HS-CAN
  • TCM
Engine load % PCM HS-CAN
  • TCM
Engine malfunction indicator lamp (MIL) request PCM HS-CAN
  • IC
  • TCM
Engine malfunction indicator lamp (MIL) request TCM HS-CAN
  • PCM
Engine off timer PCM HS-CAN
  • IC
  • 4X4 control module
Engine off timer (gateway) IC MS-CAN
  • HVAC module
Engine oil pressure low SJB MS-CAN
  • IC
Engine RPM PCM HS-CAN
  • ABS module
  • IC
  • TCM
  • 4X4 control module
Engine RPM (gateway) IC MS-CAN
  • Accessory protocol interface module (APIM)
  • DCSM
  • HVAC module
Engine torque data PCM HS-CAN
  • ABS module
  • TCM
Engine torque data TCM HS-CAN
  • PCM
Engine torque reduction request ABS module HS-CAN
  • PCM
Engine torque reduction request TCM HS-CAN
  • PCM
Engine torque transfer request 4X4 control module HS-CAN
  • ABS module
Engine torque transfer status ABS module HS-CAN
  • 4X4 control module
English/Metric display mode IC MS-CAN
  • HVAC module
Fuel cap off indicator request PCM HS-CAN
  • IC
Fuel level input status (instant) sender 1 & 2 IC HS-CAN
  • PCM
Head lamp high beam status SJB MS-CAN
  • IC
Head/park lamp switch status SJB MS-CAN
  • IC
Ignition switch position IC MS-CAN
  • ACM
  • APIM
  • DCSM
  • DDM
  • DSM
  • HVAC module
  • PAM
  • SDARS module
  • Audio digital signal processing (DSP) module
Ignition switch position IC HS-CAN
  • ABS module
  • PCM
  • RCM
  • TCM
  • 4X4 control module
Illumination dimmer level SJB MS-CAN
  • ACM
  • HVAC module
  • IC
Integrated key head transmitter (IKT) data IC MS-CAN
  • SJB
IKT program request IC MS-CAN
  • SJB
IKT response SJB MS-CAN
  • IC
Key fob button status SJB MS-CAN
  • DSM
Key-in-ignition status IC MS-CAN
  • SJB
  • DSM
Key pad button status SJB MS-CAN
  • DSM
Lamp outage status SJB MS-CAN
  • IC
Memory 1/Memory 2 switch status DDM MS-CAN
  • DSM
Mirror adjust switch status DDM MS-CAN
  • DSM
Navigation radio rolling wheel count ABS module HS-CAN
  • IC
Navigation radio rolling wheel count (gateway) IC MS-CAN
  • ACM
Occupant classification system (OCS) data OCSM HS-CAN
  • RCM
OCS data RCM HS-CAN
  • OCSM
OCS serial number and calibration OCSM HS-CAN
  • RCM
Odometer count PCM HS-CAN
  • IC
Parking aid disable switch status IC MS-CAN
  • PAM
Parking aid sounder audio mute command PAM MS-CAN
  • ACM
Parking aid system status PAM MS-CAN
  • IC
Parking brake status SJB MS-CAN
  • IC
Parking brake status (gateway) IC HS-CAN
  • PCM
  • 4X4 control module
Passive anti-theft system (PATS) OK to start IC HS-CAN
  • PCM
PATS security data PCM HS-CAN
  • IC
PATS theft condition PCM HS-CAN
  • IC
Perimeter alarm disable switch status DDM MS-CAN
  • SJB
RCM serial number RCM HS-CAN
  • OCSM
Safety belt indicator request RCM HS-CAN
  • IC
Safety belt indicator status IC HS-CAN
  • RCM
Safety Belt-Minder® chime/flash request RCM HS-CAN
  • IC
Speed control deactivate switch status PCM HS-CAN
  • TCM
Speed control indicator request PCM HS-CAN
  • IC
Speed control status PCM HS-CAN
  • IC
  • TCM
Throttle position PCM HS-CAN
  • TCM
Tire pressure monitoring system (TPMS) status SJB MS-CAN
  • IC
TPMS sensor status (LF, RF, RR, LR) SJB MS-CAN
  • IC
Tire size information ABS module HS-CAN
  • PCM
Traction control disable switch status IC HS-CAN
  • ABS module
  • PCM
Traction control indicator request ABS module HS-CAN
  • PCM
  • RCM
Transmission gear ratio TCM HS-CAN
  • ABS module
  • PCM
  • 4X4 control module
Transmission gear ratio desired PCM HS-CAN
  • TCM
Transmission malfunction indicator request TCM HS-CAN
  • IC
Transmission output shaft speed TCM HS-CAN
  • PCM
Transmission overdrive indicator request TCM HS-CAN
  • IC
Transmission selector (PRNDL) range TCM HS-CAN
  • ABS module
  • IC
  • PCM
Transmission selector (PRNDL) range (gateway) IC MS-CAN
  • ACM
  • DSM
  • PAM
  • SJB
Transmission shift in progress TCM HS-CAN
  • ABS module
  • PCM
Transmission temperature TCM HS-CAN
  • PCM
Transmission torque converter lockup request PCM HS-CAN
  • TCM
Transmission torque converter lockup status TCM HS-CAN
  • PCM
Transmission turbine shaft speed TCM HS-CAN
  • PCM
Turn signal request SJB MS-CAN
  • IC
Vehicle speed PCM HS-CAN
  • APIM
  • IC
  • RCM
Vehicle speed (gateway) IC MS-CAN
  • ACM
  • HVAC module
  • DCSM
  • PAM
  • SJB
  • DSP module
VIN information PCM HS-CAN
  • RCM
  • OCSM
  • TCM
  • IC
  • ABS module
  • 4X4 control module
Wheel speed output (RF, LF, RR, LR) ABS module HS-CAN
  • PCM
  • TCM
  • 4X4 control module
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