B1503

DTC B1503: Evaporator Temperature Sensor Circuit Malfunction

Wiring Diagram










DTC Detecting Condition and Trouble Area






DTC Troubleshooting

NOTE:

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

1.
Was "Air Conditioning System Check" performed?
YES -
Go to Step 2.
NO -
Go to Air Conditioning System Check 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 ohms
- 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?
YES -
Go to Step 3.
NO -
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?
YES -
Go to Step 4.
NO -
Substitute a known-good HVAC control module and recheck.

4. Evaporator temperature sensor check

Check evaporator temperature sensor for performance referring to Inspection Evaporator Temperature Sensor Inspection:Auto A/C.

Is it in good condition?
YES -
Substitute a known-good HVAC control module and recheck.
NO -
Replace evaporator temperature sensor.