Suzuki 2006 SX4 Service Manual page 923

DTC Troubleshooting
NOTE
When DTC B1503, B1504, B1511 and B1512 are indicated together, it is possible that sensor ground
circuit is open.
Step
1 Was "Air Conditioning System Check" performed?
2 Wire harness check
1) Turn ignition switch to OFF position.
2) Disconnect connectors from inside air temperature
sensor and HVAC control module.
3) Check for proper connection to each signal circuit
terminal and ground circuit terminal of inside air
temperature sensor and HVAC control module
connectors.
4) If OK, check that inside air temperature sensor circuit is
as follows.
• Wiring harness resistance of each inside air
temperature sensor signal circuit and ground circuit is
less than 3 Ω
• Insulation resistance between inside air temperature
sensor signal circuit and vehicle body ground is
infinity
• Circuit voltage of each inside air temperature sensor
signal circuit and ground circuit is 0 – 1 V with ignition
switch turned ON
Are they in good condition?
3 Inside air temperature sensor reference voltage check
1) Connect connector to HVAC control module with ignition
switch turned OFF.
2) Turn ignition switch to ON position.
3) Measure voltage between signal terminal and ground
terminal of inside air temperature sensor connector.
Is voltage 4.5 – 5.5 V?
4 Inside air temperature sensor check
1) Check inside air temperature sensor for performance
referring to "Inside Air Temperature Sensor Inspection".
Is it in good condition?
Action
Air Conditioning System: Automatic Type 7B-58
Yes
Go to Step 2.
Go to Step 3.
Go to Step 4.
Substitute a known-
good HVAC control
module and recheck.
No
Go to "Air Conditioning
System Check".
Inside air temperature
sensor signal circuit
and/or ground circuit are
open, short or high
resistance.
Substitute a known-
good HVAC control
module and recheck.
Replace inside air
temperature sensor.