Suzuki 2006 SX4 Service Manual page 936

7B-71 Air Conditioning System: Automatic Type
DTC Detecting Condition and Trouble Area
Serial communication signal is higher than or lower than specified value for
specified time continuously.
DTC Troubleshooting
Step
1 Was "Air Conditioning System Check" performed?
2 Back-up power supply circuit fuse check
1) Check back-up power supply circuit fuse for blowing.
Is fuse(s) blown?
3 Wire harness check
1) Turn ignition switch to OFF position.
2) Disconnect connectors from BCM, information display
and HVAC control module.
3) Check for proper connection to serial communication
circuit terminal of BCM, information display and HVAC
control module connectors.
4) If OK, check that serial communication circuit is as
follows.
• Wiring harness resistance of serial communication
circuit is less than 3 Ω
• Insulation resistance between serial communication
circuit terminal and vehicle body ground is Infinity
• Circuit voltage of serial communication circuit is 0 - 1
V with ignition switch turned ON
Are they in good condition?
4 Serial communication signal check
1) Connect connectors to BCM and HVAC control module
with ignition switch turned OFF.
2) Turn ignition switch to ON position.
3) Check that serial communication signal is outputted from
BCM referring to "Voltage Check" under "Inspection of
BCM and Its Circuits in Section 10B".
Is serial communication signal outputted?
5 Communication data check
1) Connect connector to information display with ignition
switch turned OFF.
2) Check that serial communication signal is outputted from
BCM referring to "Voltage Check" under "Inspection of
BCM and Its Circuits in Section 10B".
Is serial communication signal outputted?
DTC detecting condition
Action
Trouble area
• Back-up power supply circuit
• Serial communication circuit
• BCM
• Information display
• HVAC control module
Yes
Go to Step 2.
Replace blown fuse and
check for short in back-
up power supply circuit.
Go to Step 4.
Replace information
display.
Substitute a known-
good HVAC control
module and recheck.
No
Go to "Air Conditioning
System Check".
Go to Step 3.
Serial communication
circuit is open, short or
high resistance.
Go to Step 5.
Substitute a known-
good BCM and recheck.