B1231

Control System DTCs

DTC Troubleshooting: B1231 - (09)

DTC B1231 or DTC indicator 09 : An Open in the Evaporator Temperature Sensor Circuit

1. Problem verification:

Problem verification
-1. Clear the DTC with the HDS.

-2. Turn the ignition switch to LOCK (0), and then back to ON (II).

-3. Do the self-diagnostic with the HDS or the climate control unit How To Troubleshoot The Climate Control System.

-4. Check for DTCs.

Is DTC B1231 or 09 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 climate 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 climate control unit . Service and Repair
-NO- Repair an open in the wire between the climate control unit and the evaporator temperature sensor.