Speed sensor SUZUKI SWIFT 2008 2.G Service Workshop Manual
[x] Cancel search | Manufacturer: SUZUKI, Model Year: 2008, Model line: SWIFT, Model: SUZUKI SWIFT 2008 2.GPages: 1496, PDF Size: 34.44 MB
Page 983 of 1496

Downloaded from www.Manualslib.com manuals search engine Air Conditioning System: Automatic Type 7B-35
Electronic Control System Location
NOTE
The figure shows left-hand steering vehicle. For right-hand steering vehicle, parts with (*) are installed 
at the opposite side.
 
1
2
3 * 4 *
5
6 *
7 *
8 *
9 *
10 *
21
11
12 13
14
15161718
19
20
I5RS0C722001-01
1. ECT sensor
7. Blower motor13. AUTO switch19. MODE (air flow) selector
2. Outside air temperature sensor 8. Blower motor controller 14. Temperature selector 20. Blower speed selector
3. Sunload sensor 9. Temperature control actuator15. OFF switch21. HVAC control module
4. Air flow control actuator 10. Inside air temperature sensor 16. Air intake selector
5. Evaporator temperature sensor 11. Defroster switch 17. A/C switch
6. Air intake actuator 12. Display 18. Rear defogger switch  
Page 984 of 1496

Downloaded from www.Manualslib.com manuals search engine 7B-36 Air Conditioning System: Automatic Type
Auto A/C Electronic Control Input / Output Table
HVAC Control Module Operation DescriptionS7RS0B7221002
Temperature Control
HVAC control module calculates the target temperature 
control door position based on signals from the 
temperature selector, inside air temperature sensor, 
outside air temperature sensor and sunload sensor and 
controls the temperature control actuator so that the 
current position of the temperature control door matches 
its target position.
Fan Speed Control
HVAC control module calculates the target blower fan 
speed based on signals from the temperature selector, 
inside air temperature sensor, outside air temperature 
sensor and sunload sensor, compares it with the current 
blower fan speed inputted from the blower motor 
controller to control the current blower fan speed to the 
target level.
Air Flow Outlet Control
HVAC control module calculates the target temperature 
control door position based on signals from the 
temperature selector, inside air temperature sensor, 
outside air temperature sensor and sunload sensor. 
Using thus obtained target temperature control door 
position, it further calculates  the target air flow control 
door position and controls the ai r flow control actuator so 
that the current air flow c ontrol door position becomes 
the target position. Air Intake Position Control
HVAC control module determines the position of the air 
intake control door based on signals from the 
temperature selector, inside air temperature sensor, 
outside air temperature sensor and sunload sensor and 
selects any of the following positions by controlling the 
position of the air intake control door.
• FRESH position (FRE)
• RECIRCULATION position (REC)
• MIX position (MIX)
Refrigerant Type IdentificationS7RS0B7221003
Refer to “Refrigerant Type Identification”.
Sub-Cool A/C System DescriptionS7RS0B7221005
Refer to “Sub-Cool A/C System Description”.
A/C Operation DescriptionS7RS0B7221006
Refer to “A/C Operation Description”.
Sunload sensor
Outside air temperature sensor Evaporator temperature sensor
A/C refrigerant pressure sensor
Temperature selector
MODE (air flow) selector
Blower speed selector
Air intake selector
AUTO switch
A/C switch
Compressor
Blower motor controller
Temperature control actuator
Air flow control actuator
Air intake control actuator
BCM
ECM
Data link connector
HVAC control module
CPU
ECT sensor
Inside air temperature sensor
VSS
*
I5RS0C722002-02
*: CAN communication  
Page 987 of 1496

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Diagnostic Information and Procedures
A/C System Symptom DiagnosisS7RS0B7224001
4. Rear defogger relay 15. Evaporator temperature sensor 26. Radiator cooling fan relay No.1 37. Rear defogger switch
5. Rear defogger 16. Sunload sensor 27. Radiator cooling fan relay No.2 38. To BCM
6. Blower motor relay 17. Junction block assembly 28. Radiator cooling fan relay No.3 39. To ECM
7. Blower motor 18. ECM 29. Information display 40. To main relay
8. Blower motor controller 19. ECT sensor 30. Lighting switch 41. To main fuse
9. DLC 20. Radiator cooling fan motor 31. A/C switch 42. Back-light
10. Air intake actuator 21. Compressor relay 32. MODE (air flow) selector 43. Defroster indicator 11. Air flow control actuator 22. Compressor 33. Air intake selector 44. Rear defogger indicator
Condition Possible cause Correction / Reference Item
No cool air comes out (A/
C system does not 
operate) No refrigerant
Perform recovery, evacuation and charge 
referring to “Operation Procedure for 
Refrigerant Charge”.
Fuse blown Check related fuses, and then check for short 
circuit to ground.
A/C switch faulty Check A/C switch referring to “Inspection of 
HVAC Control Module and Its Circuit”.
Evaporator temperature sensor faulty Check evaporator temperature sensor 
referring to “Evaporator Thermistor 
(Evaporator Temperature Sensor) Inspection”.
A/C refrigerant pressure sensor faulty Check A/C refrigerant pressure sensor 
referring to “A/C Refrigerant Pressure Sensor 
and Its Circuit Inspection”.
Wiring or grounding faulty Repair as necessary.
ECT sensor faulty Check ECT sensor referring to “ECT Sensor 
Inspection in Section 1C”.
ECM faulty Check ECM referring to “A/C System 
Inspection at ECM”.
HVAC control module faulty Check HVAC control module referring to 
“Inspection of HVAC Control Module and Its 
Circuit”.
Magnet clutch faulty Check magnet clutch. Referring to “Magnet 
Clutch Inspection”.
Compressor drive belt loosened or 
broken Adjust or replace drive belt.
Compressor faulty Check compressor.
Compressor relay faulty Check compressor relay referring to 
“Compressor Relay Inspection”.
Temperature selector, blower speed 
selector, and/or air flow selector faulty Check HVAC control module referring to 
“Inspection of HVAC Control Module and Its 
Circuit”.
BCM faulty Check BCM referring to “Inspection of BCM 
and its Circuits in Section 10B”.  
Page 989 of 1496

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Cool air does not come 
out or insufficient cooling 
(A/C system normal 
operation)Insufficient or excessive charge of 
refrigerant
Check the amount of refrigerant and system 
for leaks.
Condenser clogged Check condenser referring to “Condenser 
Assembly On-Vehicle Inspection”.
A/C evaporator clogged or frosted Check A/C evaporator and evaporator 
temperature sensor referring to “Evaporator 
Inspection” and “Evaporator Thermistor 
(Evaporator Temperature Sensor) Inspection”.
Evaporator temperature sensor faulty Check evaporator temperature sensor 
referring to “Evaporator Thermistor 
(Evaporator Temperature Sensor) Inspection”.
Expansion valve faulty Check expansion valve referring to “Expansion 
Valve Inspection”.
Desiccant clogged Replace receiver/dryer.
Compressor drive belt loosened or 
broken Adjust or replace drive belt.
Magnet clutch faulty Check magnet clutch. Referring to “Magnet 
Clutch Inspection”.
Compressor faulty Check compressor.
Air in A/C system Replace receiver/dryer, and then perform 
evacuation and charge referring to “Operation 
Procedure for Refrigerant Charge”.
Air leaking from HVAC unit or air duct Repair as necessary.
Heater and ventilation system faulty Check HVAC unit.
Temperature selector faulty Check temperature selector referring to 
“Inspection of HVAC Control Module and Its 
Circuit”.
HVAC control module faulty Check HVAC control module referring to 
“Inspection of HVAC Control Module and Its 
Circuit”.
Temperature control actuator faulty Check temperature control actuator referring to 
“Temperature Control Actuator Inspection”.
Blower motor faulty Check blower motor referring to “Blower Motor 
Inspection in Section 7A”.
Excessive compressor oil in A/C system Drain excessive compressor oil from A/C 
system circuit and compressor.
Cool air does not come 
out only intermittently Wiring connection faulty
Repair as necessary.
Expansion valve faulty Check expansion valve referring to “Expansion 
Valve Inspection”.
Excessive moisture in A/C system Replace receiver/dryer, and then perform 
evacuation and charge referring to “Operation 
Procedure for Refrigerant Charge”.
Magnet clutch faulty Check magnet clutch. Referring to “Magnet 
Clutch Inspection”.
Excessive amount of refrigerant Check the amount of refrigerant.
Cool air comes out only at 
high speed Condenser clogged
Check condenser referring to “Condenser 
Assembly On-Vehicle Inspection”.
Insufficient charge of refrigerant Check the amount of refrigerant and system 
for leaks.
Air in A/C system Replace receiver/dryer, and then perform 
evacuation and charge referring to “Operation 
Procedure for Refrigerant Charge”.
Compressor drive belt loosened or 
broken Adjust or replace drive belt.
Compressor faulty Check compressor.
Condition Possible cause Correction / Reference Item  
Page 990 of 1496

Downloaded from www.Manualslib.com manuals search engine 7B-42 Air Conditioning System: Automatic Type
Abnormal Noise Symptom Diagnosis of A/C 
System
S7RS0B7224002
Refer to “Abnormal Noise Symptom Diagnosis of A/C 
System”.
DTC CheckS7RS0B7224003
Using SUZUKI Scan Tool1) Turn ignition switch to OFF position.
2) Connect SUZUKI scan tool to data link connector  (DLC) (1) located on underside of instrument panel 
at driver’s seat side.
Special tool
(A):  SUZUKI scan tool 3) Light over sunload sensor vertically with an 
incandescent lamp of approximately 100 W apart 
from about 100 mm (3.94 in.).
NOTE
If sunload sensor is not lighted over with an 
incandescent lamp, DTC B1504 is detected 
even though there is not any malfunction.
 
4) Turn ignition switch to ON position.
5) Read DTC displayed on SUZUKI scan tool.
NOTE
To know how to use SUZUKI scan tool, refer 
to operator’s manual for SUZUKI scan tool.
 
6) After completing the check,  turn ignition switch to 
OFF position and disconnect  SUZUKI scan tool from 
data link connector (DLC).
Cool air does not come 
out only at high speed
Excessive amount of refrigerant
Check the amount of refrigerant.
A/C evaporator frosted Check A/C evaporator and evaporator 
temperature sensor referring to “Evaporator 
Inspection” and “Evaporator Thermistor 
(Evaporator Temperature Sensor) Inspection”.
Insufficient air flow of 
cooled air A/C evaporator clogged or frosted
Check A/C evaporator and evaporator 
temperature sensor referring to “Evaporator 
Inspection” and “Evaporator Thermistor 
(Evaporator Temperature Sensor) Inspection”.
Air leaking from HVAC unit or air duct Repair as necessary.
Blower motor faulty Check blower motor referring to “Blower Motor 
Inspection in Section 7A”.
Wiring or grounding faulty Repair as necessary.
Condition Possible cause Correction / Reference Item
(A)
1
I5RS0A722005-01  
Page 992 of 1496

Downloaded from www.Manualslib.com manuals search engine 7B-44 Air Conditioning System: Automatic Type
3) Light over sunload sensor vertically with an incandescent lamp approximately 100 W apart from 
about 100 mm (3.94 in.).
NOTE
If sunload sensor is not lighted over with an 
incandescent lamp, DTC  B1504 is detected 
as current DTC even though there is not any 
malfunction.
 
4) Turn ignition switch to ON position.
5) Erase DTC according to instructions displayed on  SUZUKI scan tool.
NOTE
To know how to use SUZUKI scan tool, refer 
to operator’s manual for SUZUKI scan tool.
 
6) After completing the clearance, turn ignition switch to OFF position, and then di sconnect SUZUKI scan 
tool from DLC.
Not Using SUZUKI Scan Tool 1) Turn ignition switch to ON position.
2) Set temperature selector to 25  °C (77  °F). 3) Push AUTO switch (1) and 
MODE (air flow) selector 
(2) at the same time to  have history DTC displayed.
4) Push MODE (air flow) selector (2) and OFF switch  (3) at the same time while history DTC is displayed.
5) Check that “CL” (4) appears on display. “CL” means  that DTC has been cleared.
DTC TableS7RS0B7224005
CAUTION! 
Be sure to perform “Air Conditioning Sy stem Check” before starting diagnosis.
 
1
2
3
2
4
I5RS0A722008-01
DTC No. 
(displayed  on 
SUZUKI 
scan tool) DTC 
(indicated  on 
display of  HVAC 
control 
module) Priority of 
display 
(current  DTC) Priority 
of 
display 
(history  DTC) Diagnosis
“AUTO” 
indicator  lamp
 )  B1502 21 1 1 Inside air temperature sensor and/or its 
circuit malfunction Open
Flashed
22 2 2 Short
 )  B1503 31 3 3 Evaporator temperature sensor and/or its 
circuit malfunction Open
Flashed
32 4 4 Short
 )  B1504 41 21 — Sunload sensor and/or its circuit 
malfunction Open —
42 5 5 Short Flashed
 )  B1511 61 6 6 Temperature control actuator (position 
sensor) and/or its circuit malfunction Open
Flashed
62 7 7 Short
 )  B1512 71 8 8 Air flow control actuator (position sensor) 
and/or its circuit malfunction Open
Flashed
72 9 9 Short
 )  B1513 63 10 10 Temperature control actuator and/or its circuit malfunction Flashed
 )  B1514 73 11 11 Air flow control actuator and/or its circuit malfunction Flashed
 )  B1541 E1 12 — HVAC control module back-up power supply malfunction —
 )  B1546 d5 22 — A/C refrigerant pressure malfunction —
 )  B1551 91 13 12
Serial communication circuit malfunction Open
Flashed
92 14 13 Short
 )  B1552 94 15 14 Serial communication signal malfunction Flashed
 )  B1553 A4 16 15 CAN communication signal malfunction Flashed
 )  B1557 b4 19 16 Vehicle speed sensor signal malfunction —
 )  B1561 54 17 17 Engine coolant temperature sensor signal malfunction Flashed  
Page 993 of 1496

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NOTE
When no current DTC is detected, all contents displayed on display (1) of HVAC control module and 
defroster indicator (2) flash at the same time.
 
Fail-Safe TableS7RS0B7224006
When any of the following malfunctions (DTCs) is detected, fail-safe mode is activated.
However, when HVAC control module detects normal ope ration of A/C system, fail-safe mode is cancelled.
 )
 B1562 14 18 18 Outside air temperatur e sensor signal malfunction Flashed
 )  B1563 d4 20 19 A/C refrigerant pressure sensor signal malfunction —
— See NOTE 
below 
(current  DTC) ——Normal —
00 (history  DTC)
DTC No. 
(displayed  on 
SUZUKI 
scan tool) DTC 
(indicated  on 
display of  HVAC 
control 
module) Priority of 
display 
(current  DTC) Priority 
of 
display 
(history  DTC) Diagnosis
“AUTO” 
indicator  lamp
1
2
I5RS0A722009-01
DTC No.
Trouble Area Fail-Safe Operation
 )
B1502 Inside air temperature sensor and/
or its circuit HVAC control module controls actu
ators assuming that inside air 
temperature is 25 ° C (77 °F).
 )
B1503 A/C evaporator temperature sensor 
and its circuit • HVAC control module turn
s off A/C switch signal.
• HVAC control module controls actu ators assuming that evaporator 
temperature is 0 ° C (32 °F).
 )
B1504 Sunload sensor and/or its circuit HVAC control module controls actu
ators assuming that amount of 
sunlight is 0 W/m
2.
 ) B1551 Serial communication circuit
HVAC control module controls actuators assuming that outside air 
temperature is 20 ° C (68 °F), engine coolant temperature is 80  °C 
(176  °F), and vehicle speed is 40 km/h (25 mph).
 )
B1552 Serial communication circuit
 )
B1553 CAN communication circuit
 )
B1557 Vehicle speed sensor and/or its 
circuit HVAC control module controls act
uators assuming that vehicle speed 
is 40 km/h (25 mph).
 )
B1561 Engine coolant temperature sensor 
and/or its circuit HVAC control module controls act
uators assuming that engine coolant 
temperature is 80 ° C (176 °F).
 )
B1562 Outside air temperature sensor 
and/or its circuit HVAC control module controls actu
ators assuming that outside air 
temperature is 20 ° C (68 °F).  
Page 994 of 1496

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Scan Tool DataS7RS0B7224007
As the data values given in the following are standard values estimated on the basis of values obtained from the 
normally operation vehicles by using a scan tool, use them as reference values. Even when the vehicles are in good 
condition, there may be cases where the checked values do not fall within each specifies data range. Therefore, 
judgement as abnormal should not be ma de by checking with these data alone.
Scan Tool Data Condition Normal Condition / Reference 
Va l u e
 )  TEMP CONT 
SWITCH Each reference value is relative to the position of 
temperature selector of HVAC control module. Max Cool, 18.5 
°C (65 ° F), 19 °C (66 
° C) – 31  °C (88  °F), 31.5  °C (89  °F), 
Max Hot
 )  CABIN 
TEMPERATURE Reference value is relative to in-car temperature. –6.5 
°C – 57.25 ° C 
(20.3  °F – 135.05  °F)
 )  OUTSIDE AIR TEMP Reference value is relative to outside air 
temperature. –23.3 
°C – 65.95  °C 
(–9.94  °F – 150.71  °F)
 )  EVAPORATOR 
TEMP Reference value is relative to temperature of 
evaporator. –29.7 
°C – 59.55  °C 
(–21.46  °F – 139.19  °F)
 )  COOLANT TEMP At specified id le speed after warming up. 80 °C – 100  °C (176 ° F – 212 ° F)
 )  SUN LOAD Reference value depends on the situation. 0 W/m
2 – 4447.8 W/m2
 )MODE CONT 
SWITCH Each reference value is relative to the position of air 
flow selector of HVAC control module.
AUTO, FACE, B/L, FOOT, D/F, DER
 )  FAN CONT SWITCH Each reference value is relative to the position of 
blower speed selector of HVAC control module. AUTO, OFF, 1st, 2nd – 7th, 8th
 )  FAN DESIRED VOLT Reference value is relative to the position of blower 
speed selector of HVAC control module. 0 – 16.0 V
 )  AIR MIX POS SEN Reference value is relative to the position of 
temperature selector of HVAC control module. about 2.0 V (Max Hot)
about 4.0 V (Max Cool)
 ) MODE POS SENSOR Reference value is relative to the position of air flow 
selector of HVAC control module. about 1.6 V (DEF)
about 4.0 V (VENT)
 )  A/C CONT SIG A/C system is ON. ON
A/C system is OFF. OFF
 )  BLOWER LOAD SIG Position of blower speed selector is 1st position or 
more.
ON
Position of blower speed selector is OFF position. OFF
 )  AIR INTAKE MODE Fresh air (FRE) mode is activated. FRE
Recirculation air (REC) mode is activated. REC
AUTO mode is activated. AUTO
 )  REFRIGERANT 
PRESSURE Engine running. A/C ON (A/C is operating) 
at ambient temperature: 
30 
°C (86  °F) 1470 – 1770 kPa For more details, 
refer to pressure  of high pressure 
gauge under “A/C System  Performance Inspection”
A/C OFF (A/C is not 
operating) at ambient 
temperature: 30  °C (86 
° F) and engine coolant 
temperature: 90  ° – 100 
° C 600 – 1000 kPa After longer than 10 
min from A/C switch turned off
 )  A/C COMP CLUTCH Engine running. A/C switch and blower 
motor switch turned ON
ON
A/C switch and/or blower 
motor switch turned OFF OFF
 )  DFR INDICATOR Defroster indicator 
lamp is lighted. ON
Defroster indicator la mp is not lighted. OFF
 )  VEHICLE SPEED At stop. OFF
0 km/h (0 mph)  
Page 995 of 1496

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Scan Tool Data Definitions
TEMP CONT SWITCH (TEMPERATURE SELECTOR):   Position of temperature control 
selector of HVAC control module
CABIN TEMPERATURE:   In-car temperature detected 
by inside air temperature sensor installed in HVAC 
control module
OUTSIDE AIR TEMP (OUTSIDE AIR  TEMPERATURE):   Outside air temperature 
detected by outside air temperature sensor installed 
in front bumper member
EVAPORATOR TEMP (EVAPORATOR  TEMPERATURE):   Temperature of air passed 
through evaporator
COOLANT TEMP (ENGINE COOLANT  TEMPERATURE):   Engine coolant temperature 
detected by engine coolant temperature sensor
SUN LOAD:   Amount of sunlight detected by sunload 
sensor installed on the driver side on the dashboard
MODE CONT SWITCH (MODE (AIR FLOW)  SELECTOR):   Position of air flow selector of HVAC 
control module
FAN CONT SWITCH (BLOWER SPEED SELECTOR):   Position of blower speed selector of HVAC control 
module
FAN DESIRED VOLT:   Voltage for blower motor AIR MIX POS SEN (TEMPERATURE CONTROL 
ACTUATOR POSITI ON SENSOR):  Input signal 
from position sensor in temperature control actuator
MODE POS SENSOR (AIR FLOW CONTROL  ACTUATOR POSITI ON SENSOR):  Input signal 
from position sensor in air flow control actuator
A/C CONT SIG (A/C SWITCH SIGNAL, ON or OFF):   State of A/C switch
BLOWER LOAD SIG (BLO WER FAN LOAD SIGNAL, 
ON or OFF):   ON: Position of blower speed selector 
is 1st position or more / OFF: Position of blower 
speed selector is OFF position.
AIR INTAKE MODE (AUTO, FRE or REC):   State of air 
intake mode
REFRIGERANT PRESSURE (A/C REFRIGERANT  ABSOLUTE PRESSURE):   This parameter 
indicates A/C refrigerant absolute pressure 
calculated by ECM
A/C COMP CLUTCH (A/C COMPRESSOR MAGNET  CLUTCH, ON or OFF):   This parameter indicates 
the state of the A/C switch
DFR INDICATOR (DEFROSTER INDICATOR LAMP,  ON or OFF):   State of defroster indicator lamp
VEHICLE SPEED:   It is computed based on pulse 
signals from vehicle speed sensor
Air Conditioning System CheckS7RS0B7224008
Step Action YesNo
1 Customer complaint analysis
1) Perform   )”Customer complaint analysis”.
Was customer complaint analysis performed? Go to Step 2.
Perform customer 
complaint analysis.
2 Visual inspection
1) Perform   )“Visual inspection”.
Is there any faulty condition? Repair or replace 
malfunction part.
Go to Step 3.
3 DTC check
1) Perform   )“DTC check”.
Is there any DTC code? Go to Step 4.
Go to Step 5.
4 Troubleshooting malfunction
1) Perform   ) “Troubleshooting malfunction”.
Is there any faulty condition? Repair or replace 
malfunction part, and go 
to Step 7.
Go to Step 5.
5 Perform A/C system symptom diagnosis
1) Inspect and repair referri ng to “A/C System Symptom 
Diagnosis”.
Is there any faulty condition? Repair or replace 
malfunction part, and go 
to Step 7.
Go to Step 6.
6 Check for intermittent problem
1) Check for intermittent troubles referring to “Intermittent 
and Poor Connection Inspection in Section 00”.
Is there any faulty condition? Repair or replace 
malfunction part, and go 
to Step 7.
Go to Step 7.
7 Final confirmation test
1) Perform   ) “Final confirmation test”.
Is there any malfunction code? Go to Step 4.
End.  
Page 1013 of 1496

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DTC Troubleshooting
DTC B1553: CAN Communication Signal MalfunctionS7RS0B7224021
DTC Detecting Condition and Trouble Area
DTC Troubleshooting
DTC B1557: Vehicle Speed Sensor Signal MalfunctionS7RS0B7224022
DTC Detecting Condition and Trouble Area
DTC TroubleshootingStep Action Yes No
1 Serial communication signal data check
1) Connect scan tool to DLC with ignition switch turned 
OFF.
2) Start engine and select “DATA LIST” mode on scan tool.
3) Check “Refrigerant Pressure”, “Vehicle Speed”, “Coolant  Temp” and “Outside Air Temp” varies displayed on scan 
tool.
Is displayed each va ries described varies in “Scan Tool 
Data”? Intermittent trouble. 
Check for intermittent 
referring to “Intermittent 
and Poor Connection 
Inspection in Section 
00”.
Go to Step 2.
2 Serial communication signal check
1) Connect connectors to BCM and HVAC control module.
2) Using oscilloscope, check that serial communication 
signal is outputted referring to “Reference waveform 
No.8” of “Inspection of BCM and its Circuits in Section 
10B”.
Is serial communication signal outputted at “G37-11” 
terminal of BCM connector? HVAC control module 
faulty.
BCM (included in 
junction block 
assembly) faulty.
DTC detecting condition
Trouble area
HVAC control module receives error code fr om BCM continuously.• CAN communication circuit
• BCM (included in junction block  assembly)
•ECM
• HVAC control module
Step Action YesNo
1 DTC check
1) Connect scan tool to DLC with ignition switch turned 
OFF.
2) Check ECM and BCM for DTC.
Is there DTC(s)? Go to applicable DTC 
diag. flow.
Substitute a known-
good HVAC control 
module and recheck.
DTC detecting condition
Trouble area
HVAC control module  receives error code from BCM continuously. • VSS circuit
• VSS
• HVAC control module
Step Action YesNo
1 DTC check
1) Connect scan tool to DLC with ignition switch turned 
OFF.
2) Check ECM for DTC.
Is there DTC P0500? Go to “DTC P0480: Fan 
1 (Radiator Cooling 
Fan) Control Circuit in 
Section 1A”.
Substitute a known-
good HVAC control 
module and recheck.