Manufacturer Code Charts: 12

Control System DTCs

HVAC DTC Troubleshooting: 12

DTC indicator 12 : An Open in the Evaporator Temperature Sensor Circuit

1. Problem verification:

Problem verification
-1. Turn the ignition switch to LOCK (0), and then back to ON (II).

-2. Do the Self-Diagnostic Function with the HVAC control unit How to Troubleshoot the Heating and A/C Systems (Manual A/C).

-3. Check for DTCs.

Is DTC 12 indicated?
-YES- Go to step 2.
-NO- Intermittent failure. Check for loose wires or poor connections on the evaporator temperature sensor circuit.

2. Evaporator temperature sensor check:

Evaporator temperature sensor check
-1. Turn the ignition switch to LOCK (0).

-2. Remove the evaporator temperature sensor, and test it Service and Repair.

Is the evaporator temperature sensor OK?
-YES- With the evaporator temperature sensor disconnected, go step 3.
-NO- Replace the evaporator temperature sensor Service and Repair.

3. Open wire check (TEVA line):

Open wire check (TEVA line)
-1. Disconnect the following connector.





-2. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The TEVA wire is OK. Go to step 4.
-NO- Repair an open in the wire between the HVAC control unit and the evaporator temperature sensor.

4. Open wire check (SENSOR_COM/SENS-COM lines):

Open wire check (SENSOR_COM/SENS-COM lines)
-1. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The SENSOR_COM/SENS-COM wires are OK. Replace the HVAC control unit HVAC Control Unit Removal and Installation (With Navigation).
-NO- Repair an open in the wire between the HVAC control unit and the evaporator temperature sensor.