Dtc B1503: A/C Evaporator Air Temperature Sensor And/Or Its Circuit Malfunction - Suzuki Swift Sport 2004 Service & Repair Manual

7B-50 Air Conditioning System: Automatic Type
Step
2 Inside air temperature sensor signal circuit check
1) Disconnect connector from HVAC control module with
ignition switch turned OFF.
2) Check for proper connection to HVAC control module
connector at "G52-6" and "G52-3" terminals.
3) If OK, measure resistance between "PNK/BLK" wire
terminal of inside air temperature sensor connector and
"G52-6" terminal of HVAC control module connector.
Is resistance below 5
3 Inside air temperature sensor signal circuit check
1) Measure resistance between "PNK/BLK" wire terminal of
inside air temperature sensor connector and vehicle
body ground.
Is resistance infinity?
4 Inside air temperature sensor signal circuit check
1) Measure voltage between "PNK/BLK" wire terminal of
inside air temperature sensor connector and vehicle
body ground with ignition switch turned ON.
Is voltage 0 V?
5 Inside air temperature sensor ground circuit check
1) Connect HVAC control module connector with ignition
switch turned OFF.
2) Measure resistance between "ORN" wire terminal of
inside air temperature sensor connector and vehicle
body ground.
Is resistance below 5
6 Inside air temperature sensor ground circuit check
1) Measure resistance between "G52-3" terminal of HVAC
control module connector and vehicle body ground.
Is resistance below 5
7 Inside air temperature sensor check
1) Check inside air temperature sensor referring to "Inside
Air Temperature Sensor Inspection".
Is it in good condition?

DTC B1503: A/C Evaporator Air Temperature Sensor and/or Its Circuit Malfunction

Wiring Diagram
2
WHT/BLK
1. HVAC control module
Action
Ω
?
Ω
?
Ω
?
1
5V
G52-4
ORN G52-3
3
2. Evaporator temperature sensor
Yes
Go to Step 3.
Go to Step 4.
Go to Step 5.
Go to Step 7.
"ORN" wire open or high
resistance circuit.
HVAC control module
faulty.
G52
8 7 6 5 4 3 2 1 10
16 15 14 13 12 11 10 9 20
3. To other sensors
No
"PNK/BLK" wire open or
high resistance circuit.
"PNK/BLK" wire shorted
to ground circuit.
"PNK/BLK" wire shorted
to other circuit.
Go to Step 6.
HVAC control module
faulty.
Inside air temperature
sensor faulty.
S7RS0B7224011
G51
9 8 7 6 5 4 3 2 1
19 18 17 16 15 14 13 12 11
I5RS0A722011-01