Dtc B1557: Vss Signal Failure; Dtc B1561: Ect Signal Failure - Suzuki SX4 Service Manual

7B-70 Air Conditioning System: Automatic Type
DTC Troubleshooting
Step
1 Was "Air Conditioning System Check" performed?
2 DTC check
1) Connect scan tool to DLC with ignition switch turned
OFF.
2) Check DTC in BCM.
Is DTC U0073 (No.0073), U0100 (No.0100) and/or U0155
(No.0155) detected?

DTC B1557: VSS Signal Failure

DTC Detecting Condition and Trouble Area
HVAC control module receives invalid data of VSS signal from BCM.
DTC Troubleshooting
Step
1 Was "Air Conditioning System Check" performed?
2 DTC check
1) Connect scan tool to DLC with ignition switch turned
OFF.
2) Check DTC in ECM.
Is DTC P0500 detected?

DTC B1561: ECT Signal Failure

DTC Detecting Condition and Trouble Area
HVAC control module receives invalid data of ECT signal from BCM.
DTC Troubleshooting
Step
1 Was "Air Conditioning System Check" performed?
2 DTC check
1) Connect scan tool to DLC with ignition switch turned
OFF.
2) Check DTC in ECM.
Is DTC P0116, P0117 or P0118 detected?
Action
DTC detecting condition
Action
DTC detecting condition
Action
Yes
Go to Step 2.
Go to applicable DTC
diag. flow.
Trouble area
• VSS circuit
• VSS
• HVAC control module
Yes
Go to Step 2.
Go to applicable DTC
diag flow.
Trouble area
• ECT sensor circuit
• ECT sensor
• HVAC control module
Yes
Go to Step 2.
Go to applicable DTC
diag. flow.
No
Go to "Air Conditioning
System Check:
Automatic Type".
Substitute a known-
good HVAC control
module and recheck.
S7RW0A7224023
No
Go to "Air Conditioning
System Check:
Automatic Type".
Substitute a known-
good HVAC control
module and recheck.
S7RW0A7224024
No
Go to "Air Conditioning
System Check:
Automatic Type".
Substitute a known-
good HVAC control
module and recheck.