Principles of Operation: HS-Can

WARNING: This page is about a different car, the 2008 Ford RV Cutaway, 2008 Ford Econoline, 2008 Ford E450 Super Duty, and 2008 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

The HS-CAN 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 and designed for real time information transfer and control. 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 following modules are on the HS-CAN:

ABS module
Instrument cluster (IC)
PCM
Restraints control module (RCM)

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 for all network modules
HS-CAN (+) open	Unreliable communication possible for all network modules
HS-CAN (-) open	Unreliable communication possible for all network modules
Module loss of voltage or ground	No communication
Module internal failure	No communication

The following chart describes the specific 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)
ABS indicator request	ABS module	HS-CAN	Instrument cluster (IC)
A/C clutch status	PCM	HS-CAN	IC
Accelerator pedal position	PCM	HS-CAN	ABS module RCM
Airbag deployment status	RCM	HS-CAN	IC PCM
Airbag warning indicator request	RCM	HS-CAN	IC
Airbag warning indicator status	IC	HS-CAN	RCM
Axle ratio	PCM	HS-CAN	ABS module RCM
Barometric pressure	PCM	HS-CAN	IC
Barometric pressure (gateway)	IC	MS-CAN	VSM
Belt-Minder® indicator/chime request	RCM	HS-CAN	IC
Belt-Minder® indicator/chime status	IC	HS-CAN	RCM
Belt-Minder® programming mode request	RCM	HS-CAN	IC
Brake deactivator switch status	PCM	HS-CAN	ABS module IC
Brake fluid level	IC	HS-CAN	ABS module
Brake lamp switch status	PCM	HS-CAN	ABS module IC RCM
Brake lamp switch status (gateway)	IC	MS-CAN	Vehicle security module (VSM)
Brake warning indicator request	ABS module	HS-CAN	IC
Courtesy lamp request	VSM	MS-CAN	IC
Door ajar status (LF, RF, RR)	IC	HS-CAN	ABS module
Door ajar status (LF, RF, RR)	IC	MS-CAN	VSM
Engine coolant temperature	PCM	HS-CAN	ABS module IC
Engine fuel consumption data	PCM	HS-CAN	IC
Engine malfunction indicator lamp (MIL) request	PCM	HS-CAN	IC
Engine off timer	PCM	HS-CAN	ABS module IC
Engine RPM	PCM	HS-CAN	ABS module IC
Engine RPM (gateway)	IC	MS-CAN	VSM
Engine throttle position	PCM	HS-CAN	RCM
Engine torque data	PCM	HS-CAN	ABS module
Engine torque reduction request	ABS module	HS-CAN	PCM
Engine type configuration	PCM	HS-CAN	ABS module
Fail-safe cooling indicator request	PCM	HS-CAN	IC
Fail-safe electronic throttle control (ETC) indicator request	PCM	HS-CAN	IC
Fuel cap off indicator request	PCM	HS-CAN	IC
Fuel level input status (instant)	IC	HS-CAN	PCM
Ignition switch position	IC	HS-CAN	ABS module
Ignition switch position	IC	MS-CAN	VSM
Key-in-ignition status	IC	MS-CAN	VSM
Odometer count	PCM	HS-CAN	IC
Panic mode request	VSM	MS-CAN	IC
Parking brake status	IC	HS-CAN	ABS module PCM
Passive anti-theft system (PATS) security data	IC	HS-CAN	PCM
PATS security data	PCM	HS-CAN	IC
Speed control indicator request	PCM	HS-CAN	ABS module IC RCM
Stability control disable switch status	ABS module	HS-CAN	IC
Stability control event in progress	ABS module	HS-CAN	PCM RCM
Stability control indicator (or message) request	ABS module	HS-CAN	IC
Tire pressure monitor system (TPMS) warning request	VSM	MS-CAN	IC
Tire size information	ABS module	HS-CAN	PCM
Tow-haul indicator request	PCM	HS-CAN	IC
Traction control event in progress	ABS module	HS-CAN	PCM RCM
Traction control off switch status	IC	HS-CAN	ABS module PCM
Transmission fluid temperature	PCM	HS-CAN	IC
Transmission output shaft speed (OSS)	PCM	HS-CAN	ABS module
Transmission overdrive cancel indicator request	PCM	HS-CAN	IC
Transmission selector (PRNDL) range	PCM	HS-CAN	ABS module IC
Transmission selector (PRNDL) range (gateway)	IC	MS-CAN	VSM
Transmission shift in progress	PCM	HS-CAN	ABS module
Transmission warning indicator request	PCM	HS-CAN	IC
Vehicle speed	PCM	HS-CAN	ABS module IC RCM
Vehicle speed (gateway)	IC	MS-CAN	VSM
VIN information	PCM	HS-CAN	ABS module RCM
Wait-to-start lamp status	PCM	HS-CAN	IC
Water-in-fuel indicator request	PCM	HS-CAN	IC
Wheel speed (LF, RF, RR, LR)	ABS module	HS-CAN	PCM