DTC Troubleshooting

WARNING: This page is about a different car, the 2011 Suzuki SX4. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: When DTC B1502, B1504, B1511 and B1512 are indicated together, it is possible that sensor ground circuit is open.

B1503: SYMPTOM TROUBLESHOOTING REFERENCE CHART

Step	Action	YES	NO
1	Was "Air Conditioning System Check" performed?	Go to Step 2.	Go to AIR CONDITIONING SYSTEM CHECK: AUTO A/C .
2	Wire harness check Turn ignition switch to OFF position. Disconnect connectors from evaporator temperature sensor and HVAC control module. Check for proper connection to each signal circuit terminal and ground circuit terminal of evaporator temperature sensor and HVAC control module connectors. If OK, check that evaporator temperature sensor circuit is as follows. Wiring harness resistance of each evaporator temperature sensor signal circuit and ground circuit is less than 3 Ω Insulation resistance between evaporator temperature sensor signal circuit and vehicle body ground is Infinity Circuit voltage of each evaporator temperature sensor signal circuit and ground circuit is 0 - 1 V with ignition switch turned ON Are they good condition?	Go to Step 3.	Evaporator temperature sensor signal circuit and/or ground circuit are open, short or high resistance.
3	Evaporator temperature sensor reference voltage check Connect connector to HVAC control module with ignition switch turned OFF. Turn ignition switch to ON position. Measure voltage between signal terminal and ground terminal of evaporator temperature sensor connector. Is voltage 4.5 - 5.5 V?	Go to Step 4.	Substitute a known-good HVAC control module and recheck.
4	Evaporator temperature sensor check Check evaporator temperature sensor for performance referring to EVAPORATOR TEMPERATURE SENSOR INSPECTION: AUTO A/C . Is it in good condition?	Substitute a known-good HVAC control module and recheck.	Replace evaporator temperature sensor.