Honda Fit: Multiplex Integrated Control System Description
Body Controller Area Network (B-CAN) and Fast Controller Area Network (F-CAN)
The body controller area network (B-CAN) and the fast controller area network (F-CAN) share information between multiple electronic control units (ECUs). B-CAN communication moves at a slower speed (33.33 kbps) for convenience related items and for other functions. F-CAN information moves at a faster speed (500 kbps) for ‘‘real time'' functions such as fuel and emissions data. To allow both systems to share information, the gauge control module translates information from B-CAN to F-CAN and from F-CAN to B-CAN.This is called the Gateway Function.
Gateway Function
The gauge control module acts as a gateway to allow both systems to share information. The gauge control module translates and relays the information from B-CAN to F-CAN and from F-CAN to B-CAN.
Network ‘‘Loss of Communication'' Error Checking Function
The ECUs on the CAN circuit send messages to each other. If there are any malfunctions on the network, the LCD display on the gauge control module can indicate the error messages by entering the gauge control module self-diagnostic function.
Self-diagnostic Function
By connecting the HDS to the data link connector (DLC), the HDS can retrieve the diagnostic information from the MICU via a diagnostic line called K-LINE. The K-LINE is separate from the CAN lines, and is connected to the CAN related ECUs. The MICU is a gateway between the HDS and B-CAN related ECUs, and it sends B-CAN diagnostic information to the HDS. When doing a function test with the HDS, the HDS sends an output signal through the K-LINE to the MICU. The MICU either relays the request to another ECU or commands the function itself.
Wake-up and Sleep Function
The multiplex integrated control system has wake-up and sleep functions to decrease parasitic draw on the battery when the ignition switch is at LOCK (0).
-
In the sleep mode, the multiplex integrated control system stops functioning (communication and CPU control) when it is not necessary for the system to operate.
-
As soon as any operation is requested (for example, a door is unlocked), the related control units in the sleep mode immediately wake-up and begin to function.
-
When the ignition switch is turned to LOCK (0) with all the doors and the tailgate closed, and the driver's door is opened then closed, there is a delay of about 40 seconds before the control unit goes from the wake-up mode to the sleep mode.
-
The sleep mode will not function if any door or the tailgate is open or if a key is in the ignition switch.
-
Electrical draw is reduced from 200 mA to less than 35 mA when in sleep mode.
NOTE: Sleep and Wake-Up Mode Test.
Fail-Safe Function
To prevent improper operation, the MICU has a fail-safe function. In the fail-safe mode, the output signal is fixed when any part of the system malfunctions (for example, a faulty control unit or communication line).
Each control unit has a hardware fail-safe function that fixes the output signal when there is a CPU malfunction and a software fail-safe function that ignores the signal from a malfunctioning control unit, which allows the system to continue operating normally.
Hardware Fail-Safe Control
Fail-safe function
When a CPU problem or an abnormal power supply voltage is detected, the MICU moves to the hardware fail-safe mode, and each system output load is set to the pre-programmed fail-safe value.
Software Fail-Safe Control
When any of the data from the B-CAN circuit cannot be received within a specified time, or an unusual combination of data is recognized, the MICU moves to the software fail-safe mode. The data that cannot be received is forced to a pre-programmed value.
Power Supply Voltage Monitoring Function
The MICU monitors the power supply voltage (back-up voltage). If the voltage drops below 10 V, the MICU will not store DTCs.
|
Input |
Output |
|
|
MICU |
Battery voltage (VBU) |
|
|
B-CAN |
MICU (UNDER 10 V) message |
Combination Light Switch
The MICU controls the lighting system based on input from the combination light switch.
|
Input |
Output |
|
|
MICU |
IG1 power supply Combination light switch (OFF) Combination light switch (ON) Combination light switch (PARKING) Combination light switch (PASSING) Combination light switch (DIMMER) |
Headlights (LO) Headlights (HI) Side marker lights Parking lights Taillights |
|
B-CAN |
Combination light switch (PARKING) message Combination light switch (HLLO) message Combination light switch (HLHI) message Combination light switch (PASSING) message |
Fog Lights
The MICU controls the fog lights based on input signal from the fog light switch.
|
Input |
Output |
|
|
MICU |
IG1 power supply Combination light switch (OFF) Combination light switch (ON) Combination light switch (FOG) |
Fog light relay |
|
B-CAN |
Combination light switch (FRFOG) message RM (FRFOGRLY) message |
Turn Signal/Hazard Warning Lights
The MICU controls the turn signal/hazard warning lights based on input from the turn signal switch and the hazard warning switch.
|
Input |
Output |
|
|
MICU |
IG1 power supply Hazard warning switch Turn signal switch (LEFT) Turn signal switch (RIGHT) |
Turn signal lights (LEFT) Turn signal lights (RIGHT) |
|
B-CAN |
MICU (HAZARDSW) message MICU (TURNRLY) message Turn signal switch (TURNL) message Turn signal switch (TURNR) message |
Entry Light
The MICU controls the interior lights based on input signals of each switch and B-CAN signals.
|
Input |
Output |
|
|
MICU |
IG1 power supply Ignition key switch Driver's door switch Front passenger's door switch Left rear door switch Right rear door switch Driver's door lock knob switch (LOCK/UNLOCK) |
Ceiling light |
|
B-CAN |
Keyless door lock signal |
Cargo Area Light
The MICU controls the cargo area light based on the tailgate latch switch.
|
Input |
Output |
|
|
MICU |
Tailgate latch switch |
Cargo area light |
Daytime Running Lights
The MICU controls the headlights as daytime running lights based on input from each switch and B-CAN signals.
|
Input |
Output |
|
|
MICU |
IG2 power supply Combination light switch (OFF) Combination light switch (ON) Combination light switch (PASSING) Combination light switch (DIMMER) |
Headlights (LO) Headlights (HI) Side maker lights Taillights |
|
B-CAN |
Parking brake switch signal IG1 METER signal |
RM (DRLKC) message RM (DRLWRN) message |
Windshield Wiper/Washer
The MICU controls the windshield wiper motor and windshield washer motor based on input signals from each switch and B-CAN signals.
|
Input |
Output |
|
|
MICU |
IG1 power supply Windshield Wiper switch (INT) Windshield Wiper switch (LO) Windshield Wiper switch (HI) Windshield Wiper switch (MIST) Windshield Washer switch Windshield Wiper motor (AUTO STOP) Brake pedal position switch Transmission range switch (P) position (A/T) |
Windshield Wiper motor (INT) Windshield Wiper motor (LO) Windshield Wiper motor (HI) Windshield Washer motor |
|
B-CAN |
IG1 METER signal Parking brake switch signal Vehicle speed pulse signal |
Windshield wiper switch (FRINT) message Windshield wiper switch (FRWIPLO) message Windshield wiper switch (FRWIPHI) message Windshield washer switch (FRWASH) message Windshield wiper switch (FRMIST) message Windshield wiper motor (FRWIPAS) message |
Rear Window Wiper/Washer
The MICU controls the rear window wiper motor and rear window washer motor based on inputs from each switch.
|
Input |
Output |
|
|
MICU |
IG1 power supply Rear window wiper motor switch Rear window washer motor switch Windshield washer switch Windshield wiper switch (INT) Windshield wiper switch (LO) Windshield wiper switch (HI) Back-up light switch (M/T) Transmission range switch (R) position (A/T) |
Rear window wiper motor Rear window washer motor |
|
B-CAN |
Windshield washer switch (FRWASH) message Rear window washer switch (RRWASH) message |
Windshield/Rear Window Washer
The MICU controls the windsheild washer and the rear window washer motor based on inputs from each switch.
|
Input |
Output |
|
|
MICU |
IG1 power supply Windshield washer motor switch Rear window washer motor switch |
Rear window washer motor Windshield washer motor |
|
B-CAN |
Windshield washer switch (FRWASH) message Rear window washer switch (RRWASH) message |
Power Window Timer (Key-Off Operation)
The MICU controls the power window key-off operation based on inputs from each switch.
|
Input |
Output |
|
|
MICU |
IG1 power supply Ignition key switch Driver's door switch Front passenger's door switch |
Power window timer |
Collision Detection Signal (CDS)
The MICU controls the door lock actuators based on the IG1 and SRS (CDS) inputs.
|
Input |
Output |
|
|
MICU |
IG1 power supply |
Door/Tailgate lock actuators (UNLOCK) |
|
B-CAN |
SRS (CDSFR) message SRS (CDSSD) message SRS (CDSRR) message SRS (CDSRO) message |
Power Door Locks
The MICU controls the door lock actuators based on inputs from each switch.
|
Input |
Output |
|
|
MICU |
IG1 power supply Ignition key switch Driver's door switch Front passenger's door switch Left rear door switch Right rear door switch Tailgate latch switch Driver's door lock switch (LOCK/UNLOCK) Driver's door key cylinder switch (LOCK/UNLOCK) Driver's door lock knob switch (LOCK/UNLOCK) |
Door/Tailgate lock actuators (LOCK) Door/Tailgate lock actuators (UNLOCK) |
Keyless Entry System
The MICU controls the door lock actuators based on inputs of each switch.
|
Input |
Output |
|
|
MICU |
IG1 power supply Ignition key switch Driver's door switch Front passenger's door switch Left rear door switch Right rear door switch Tailgate latch switch Driver's door lock knob switch (LOCK/UNLOCK) Driver's door lock switch (LOCK/UNLOCK) Driver's door key cylinder switch (LOCK/UNLOCK) |
Driver's door lock actuator (UNLOCK) Door/Tailgate lock actuators (LOCK) Door/Tailgate lock actuators (UNLOCK) |
|
B-CAN |
Keyless door lock signal |
Relock message |
Key Interlock (A/T)
The MICU controls the key interlock solenoid based on inputs from each switch.
|
Input |
Output |
|
|
MICU |
Ignition switch (I) Transmission range switch (P) position Park-pin switch |
Key interlock solenoid |
Security Alarm System
The MICU controls the exterior lights and the horn based on inputs of each switch.
|
Input |
Output |
|
|
MICU |
IG1 power supply Ignition key switch Audio switch Tailgate latch switch Driver's door switch Front passenger's door switch Left rear door switch Right rear door switch Driver's door key cylinder switch (LOCK/UNLOCK) Driver's door lock knob switch (UNLOCK) Front passenger's door lock knob switch (UNLOCK) Left rear door lock knob switch (UNLOCK) Right rear door lock knob switch (UNLOCK) Security hood switch |
Headlights (LO) Parking lights Side marker lights Taillights Security horn |
|
B-CAN |
Keyless door lock signal Door lock signal VALID CODE message |
MICU (SET1) message MICU (SET2) message ALARM (ACTION) message |
Answer Back Response Operation
The MICU controls the lighting system and horn based on keyless signals sent by B-CAN.
|
Input |
Output |
|
|
MICU |
Horn Headlights (LO) Taillights Side marker lights Parking lights |
|
|
B-CAN |
Answer back (PARKING) signal Answer back (HLLO) signal Answer back (HORN) signal |
Auto Door Lock
The MICU controls the door lock actuators based on inputs from each switch and B-CAN signals.
|
Input |
Output |
|
|
MICU |
IG1 power supply Driver's door switch Front passenger's door switch Left rear door switch Right rear door switch Tailgate latch switch Driver's door lock knob switch (UNLOCK) Front passenger's door lock knob switch (UNLOCK) Left rear door lock knob switch (UNLOCK) Right rear door lock knob switch (UNLOCK) Transmission range switch (P) position (A/T) Brake pedal position switch |
Door/Tailgate lock actuators (LOCK) |
|
B-CAN |
Vehicle speed signal Engine speed signal |
Auto Door Unlocks
The MICU controls the door lock actuators based on the inputs from each switch.
|
Input |
Output |
|
|
MICU |
IG1 power supply Ignition key switch Driver's door switch Front passenger's door switch Left rear door switch Right rear door switch Tailgate latch switch Driver's door lock knob switch (UNLOCK) Front passenger's door lock knob switch (UNLOCK) Left rear door lock knob switch (UNLOCK) Right rear door lock knob switch (UNLOCK) Transmission range switch (P) position Brake pedal position switch |
Door/Tailgate lock actuators (UNLOCK) Driver's door lock actuator (UNLOCK) |
Keyless Panic Function
The MICU controls the keyless PANIC function based on Panic signals sent by B-CAN.
|
Input |
Output |
|
|
MICU |
Headlights (LO) Parking lights Side marker lights Taillights Horn |
|
|
B-CAN |
PANIC singals |
HDS Inputs and Function Tests
Certain inputs happen so quickly that the HDS cannot update fast enough. Hold the switch that is being tested while monitoring the Data List. This should give the HDS time to update the signal on the Data List.
Because the HDS software is updated to support the release for newer vehicles, it is not uncommon to see system function tests that are not supported.
Make sure that the most current HDS software is loaded.
Input
|
System Menu |
Data List |
Data List Indication |
|
Lighting |
Driver's Door Switch |
OFF/ON |
|
Hazard Warning Switch |
OFF/ON |
|
|
Headlight Switch (OFF) |
OFF/ON |
|
|
Headlight Switch (PARKING) |
OFF/ON |
|
|
Headlight Switch (HEADLIGHT) |
OFF/ON |
|
|
Headlight Switch (High Beam) |
OFF/ON |
|
|
Headlight Switch (PASSING) |
OFF/ON |
|
|
Turn Signal Switch (LEFT) |
OFF/ON |
|
|
Turn Signal Switch (RIGHT) |
OFF/ON |
|
|
Fog Light Switch |
OFF/ON |
|
|
Left Turn Signal Command |
OFF/ON |
|
|
Right Turn Signal Command |
OFF/ON |
|
|
Cargo Light Command |
OFF/ON |
|
|
Headlight Command |
OFF/ON |
|
|
Headlight High Beam Command |
OFF/ON |
|
|
Parking Light Command |
OFF/ON |
|
|
Fog Light Command |
OFF/ON |
|
|
DRL Command |
OFF/ON |
Input
|
System Menu |
Data List |
Data List Indication |
|
Gauges |
Cruise Control Main Switch (ACC switch) |
OFF/ON |
|
Cruise Control Set Switch |
OFF/ON |
|
|
Cruise Control Resume Switch |
OFF/ON |
|
|
Washer Fluid Level Switch |
OFF/ON |
|
|
Gauge Select/Reset Switch |
OFF/ON |
|
|
VSA off Switch |
OFF/ON |
|
|
Parking Brake Switch |
OFF/ON |
|
|
Brake Fluid Level Switch |
OFF/ON |
|
|
Fuel Sending Unit Input 1 |
V |
|
|
Fuel Sending Unit Input 2 |
V |
|
|
ABS Indicator |
OFF/ON |
|
|
EBD Indicator (Electronic Brake Distribution) |
OFF/ON |
|
|
Cruise Control Main Switch Indicator |
OFF/ON |
|
|
MIL Indicator |
OFF/ON |
|
|
VSA Off Indicator |
OFF/ON |
|
|
VSA Indicator |
OFF/ON |
|
|
DRL Indicator |
OFF/ON |
|
|
Low Oil Pressure Indicator |
OFF/ON |
|
|
Charging System Indicator |
OFF/ON |
|
|
Maintenance Minder Indicator |
OFF/ON |
|
|
High Beam Indicator |
OFF/ON |
|
|
Parking Light ON Indicator |
OFF/ON |
|
|
Low Fuel Warning Indicator |
OFF/ON |
|
|
Security Indicator |
OFF/ON |
|
|
Fog Light Indicator |
OFF/ON |
|
|
Seatbelt Indicator |
OFF/ON |
|
|
SRS Indicator |
OFF/ON |
|
|
Speed Indicator (km/h) Command |
km/h/Fail |
|
|
Speed Indicator (mph) Command |
mile/h/Fail |
|
|
Driver's Seat Belt Buckle Switch |
OFF/ON |
|
|
A/T Gear Position Switch (R) |
OFF/ON |
|
|
A/T Gear Position Switch (P) |
OFF/ON |
Input
|
System Menu |
Data List |
Data List Indication |
|
Door Locks |
Driver's Door Switch |
OFF/ON |
|
Front Passenger's Door Switch |
OFF/ON |
|
|
Driver's Rear Door Switch |
OFF/ON |
|
|
Passenger's Rear Door Switch |
OFF/ON |
|
|
Driver's Rear Door Lock Knob Switch (UNLOCK) |
OFF/ON |
|
|
Passenger's Rear Door Lock Knob Sw. (UNLOCK) |
OFF/ON |
|
|
Driver's Door Key Cylinder Switch (LOCK) |
OFF/ON |
|
|
Driver's Door Key Cylinder Switch (UNLOCK) |
OFF/ON |
|
|
Driver's Door Lock Switch (LOCK) |
OFF/ON |
|
|
Driver's Door Lock Switch (UNLOCK) |
OFF/ON |
|
|
Driver's Door Lock Knob Switch (LOCK) |
OFF/ON |
|
|
Driver's Door Lock Knob Switch (UNLOCK) |
OFF/ON |
|
|
Front Passenger's Door Lock Knob Sw. (UNLOCK) |
OFF/ON |
|
|
Door LOCK Command |
OFF/ON |
|
|
Door UNLOCK Command |
OFF/ON |
|
|
Wiper |
Brake Pedal Position Switch |
OFF/ON |
|
Rear Wiper Auto Stop Switch |
ON/OFF |
|
|
Windshield Wiper Switch (LOW) |
OFF/ON |
|
|
Windshield Wiper Switch (HIGH) |
OFF/ON |
|
|
Windshield Wiper Switch (MIST) |
OFF/ON |
|
|
Rear Wiper Switch |
OFF/ON |
|
|
Windshield Wiper Switch (INT) |
OFF/ON |
|
|
Windshield Washer Switch |
OFF/ON |
|
|
Rear Washer Switch |
OFF/ON |
|
|
Windshield Wiper Motor PARK Switch |
OFF/ON |
|
|
Rear Wiper Command |
OFF/ON |
|
|
Rear Washer Command |
OFF/ON |
|
|
Windshield Wiper Motor HI Command |
OFF/ON |
|
|
Windshield Wiper Motor LO Command |
OFF/ON |
|
|
Windshield Washer Motor Command |
OFF/ON |
|
|
Keyless Transmitter |
Driver's Door Switch |
OFF/ON |
|
Front Passenger's Door Switch |
OFF/ON |
|
|
Driver's Rear Door Switch |
OFF/ON |
|
|
Passenger's Rear Door Switch |
OFF/ON |
|
|
Front Passenger's Door Lock Knob Sw. (UNLOCK) |
OFF/ON |
|
|
Driver's Rear Door Lock Knob Switch (UNLOCK) |
OFF/ON |
|
|
Passenger's Rear Door Lock Knob Sw. (UNLOCK) |
OFF/ON |
|
|
Trunk Knob Sw. (UNLOCK) |
OFF/ON |
|
|
Trunk Key Cylinder (UNLOCK) |
OFF/ON |
|
|
Trunk Handle Switch |
OFF/ON |
|
|
Driver's Door Key Cylinder Switch (LOCK) |
OFF/ON |
|
|
Driver's Door Key Cylinder Switch (UNLOCK) |
OFF/ON |
|
|
Driver's Door Lock Switch (LOCK) |
OFF/ON |
|
|
Driver's Door Lock Switch (UNLOCK) |
OFF/ON |
|
|
Driver's Door Lock Knob Switch (LOCK) |
OFF/ON |
|
|
Driver's Door Lock Knob Switch (UNLOCK) |
OFF/ON |
|
|
Door LOCK Command |
OFF/ON |
|
|
Door UNLOCK Command |
OFF/ON |
|
|
Driver's Door LOCK Command |
OFF/ON |
|
|
Trunk Lid Release Command |
OFF/ON |
Input
|
System Menu |
Data List |
Data List Indication |
|
Security |
Ignition Key Cylinder Switch |
OFF/ON |
|
Driver's Door Switch |
OFF/ON |
|
|
Front Passenger's Door Switch |
OFF/ON |
|
|
Driver's Rear Door Switch |
OFF/ON |
|
|
Passenger's Rear Door Switch |
OFF/ON |
|
|
Trunk Lid/Tailgate Switch |
OFF/ON |
|
|
Front Passenger's Door Lock Knob Sw. (UNLOCK) |
OFF/ON |
|
|
Driver's Rear Door Lock Knob Switch (UNLOCK) |
OFF/ON |
|
|
Passenger's Rear Door Lock Knob Sw. (UNLOCK) |
OFF/ON |
|
|
Trunk Knob Sw. (UNLOCK) |
OFF/ON |
|
|
Trunk Key Cylinder (UNLOCK) |
OFF/ON |
|
|
Trunk Handle Switch |
OFF/ON |
|
|
Hazard warning switch |
OFF/ON |
|
|
Security Hood Switch |
OFF/ON |
|
|
Driver's Door Key Cylinder Switch (LOCK) |
OFF/ON |
|
|
Driver's Door Key Cylinder Switch (UNLOCK) |
OFF/ON |
|
|
Driver's Door Lock Switch (LOCK) |
OFF/ON |
|
|
Driver's Door Lock Switch (UNLOCK) |
OFF/ON |
|
|
Driver's Door Lock Knob Switch (LOCK) |
OFF/ON |
|
|
Driver's Door Lock Knob Switch (UNLOCK) |
OFF/ON |
|
|
Door LOCK Command |
OFF/ON |
|
|
Door UNLOCK Command |
OFF/ON |
|
|
Driver's Door UNLOCK Command (Individual) |
OFF/ON |
|
|
Trunk Lid Release Command |
OFF/ON |
|
|
Headlight Command |
OFF/ON |
|
|
Headlight High Beam Command |
OFF/ON |
|
|
Parking Light Command |
OFF/ON |
|
|
Horn Command |
OFF/ON |
HDS Inputs and Function Tests
Function Test
|
System Menu |
HDS Description |
Note |
|
Door Locks |
LOCK all doors |
Outputs LOCK signal 1 time (for 0.6 seconds) to all door |
|
UNLOCK driver's side door |
Outputs UNLOCK signal 1 time (for 0.6 seconds) to driver's side door |
|
|
UNLOCK all doors |
Outputs UNLOCK signal 1 time (for 0.6 seconds) to all door |
|
|
Lighting |
Interior Light Command |
Illuminates for 30 seconds |
|
Left Turn Signal Command |
Blinks for 5 seconds |
|
|
Right Turn Signal Command |
Blinks for 5 seconds |
|
|
Hazard Flasher |
Blinks turn signal (left and right) for 15 seconds |
|
|
Headlight Command |
Operates headlight (low) for 15 seconds |
|
|
Headlight High Beam Command |
Operates headlight (high) for 15 seconds |
|
|
Parking Lights Command |
Operates Parking Light for 15 seconds |
|
|
Fog Light |
Operates fog light for 15 seconds |
|
|
Cargo Area Light |
Illuminates for 30 seconds |
|
|
Security |
Horn Command |
Operates horn for 1 second |
|
Wiper |
Windshield Wiper Motor Low Command |
Operates windshield wiper for 5 seconds (low speed) |
|
Windshield Wiper Motor High Command |
Operates windshield wiper for 5 seconds (high speed) |
|
|
Windshield Washer Command |
Operates windshield washer for 5 seconds |
|
|
Rear Wiper Motor |
Operates for 5 seconds |
|
|
Rear Wiper Washer |
Operates for 5 seconds |
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