Dtc B1552: Serial Communication Signal Malfunction - Suzuki Swift Sport 2004 Service & Repair Manual

7B-64 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 DTC check
1) Connect scan tool to DLC with ignition switch turned
OFF.
2) Disconnect connector from information display.
3) Turn ignition switch ON and check DTC.
Is there DTC B1551?
2 Wire harness check
1) Disconnect connectors from BCM and HVAC control
module.
2) Measure resistance between "G37-11" terminal of BCM
connector and "G51-7" terminal of HVAC control module
connector.
Is resistance below 5
3 Wire harness check
1) Measure resistance between "G51-7" terminal of HVAC
control module connector and vehicle body ground.
Is resistance infinity?
4 Wire harness check
1) Measure voltage between "G51-7" terminal of HVAC
control module connector and vehicle body ground with
ignition switch turned ON.
Is voltage 0 V?
5 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?

DTC B1552: Serial Communication Signal Malfunction

DTC Detecting Condition and Trouble Area
Data received by HVAC control module from BCM is erroneous continuously. • BCM (included in junction block
DTC detecting condition
Action
Ω
?
DTC detecting condition
Trouble area
• Serial communication line of BCM
• BCM (included in junction block
assembly)
• Information display
• HVAC control module
Yes
Go to Step 2.
Go to Step 3.
Go to Step 4.
Go to Step 5.
HVAC control module
faulty.
Trouble area
assembly)
• HVAC control module
No
Information display
faulty.
"YEL" wire open or high
resistance circuit.
"YEL" wire shorted to
ground circuit.
"YEL" wire shorted to
other circuit.
BCM (included in
junction block
assembly) faulty.
S7RS0B7224020