B1250

DTC B1250 DIRECTION POTENTIOMETER SHORT (HIGH)






GENERAL DESCRIPTION
The mode control actuator mounted on heater unit adjusts position of mode door by operating Direction Motor based on signal of A/C control unit. Pressing mode select switch makes the mode control actuator shift in order of vent -> B/L -> floor -> mix.

DTC DESCRIPTION
The ECM sets DTC B1250 if there is a short to power in the DR Direction actuator signal harness.

DTC Detecting Condition:

Signal Waveform And Data:

Schematic Diagram:

MONITOR DTC STATUS
1. Connect scantool to Data Link Connector (DLC).
2. Warm up the engine to normal operating temperature.




3. Monitor DTC(Diagnostics Trouble Code) on the scantool.
4. Is the same DTC displayed again?

YES - Go to "Inspection/Repair" procedure.

NO - Fault is intermittent caused by poor contact in the sensor's and/or A/C-ECM connector or was repaired and A/C-ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of vehicle Repair" procedure.

W/HARNESS INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration or damage.
3. Has a problem been found?

YES - Repair as necessary and go to "Verification of Vehicle Repair" procedure

NO - Go to "Signal circuit Short Inspection" procedure.

SIGNAL CIRCUIT SHORT INSPECTION
1. Ignition "OFF"
2. A/C-ECU : Connect, Driver Direction actuator : Disconnect
3. Measure resistance between Signal (F/B) terminal of Driver Direction actuator harness connector and ana Sensor ground terminal of Driver Direction actuator harness connector.

Specification: Infinity

4. Is "resistance" display near the specified value?

YES - Go to "Component inspection" procedure.

NO
- Check for short in harness.
- Repair as necessary and then go to "Verification of Vehicle Repair" procedure.

COMPONENT INSPECTION

CHECK DRIVER AIR MIX ACTUATOR
1. Ignition "OFF"
2. A/C-ECU, Driver Direction actuator : Disconnect.
3. Connect (+) terminal of battery to WARM (+) of Driver Direction actuator and (-) terminal to COOL (-). (Component side)
4. Verify that the temperature actuator operates to the DEF position.




5. Verify that the temperature actuator operates to the VENT position with reverse connecting.(DEF (+) and VENT (-)). (Component side)

Specification : Refer the specifications in fig.1

6. Is "Door position" display near the specified value?

YES - Go to "Check potentiometer" procedure.

NO - Substitute with a known-good Driver air mix actuator and check for proper operation. If the problem is corrected, replace Driver air mix actuator and then go to "Verification of Vehicle Repair" procedure.

CHECK POTENTIOMETER
1. Ignition "OFF"
2. A/C-ECU : Connect, Driver air mix actuator : Disconnect.
3. Ignition "ON" (ENGINE "OFF").




4. Measure voltage between Signal (F/B) terminal of Driver air mix actuator harness connector and and chassis ground. (Component side)

Specification : Refer the specifications in fig.2

5. Is "voltage" display near the specified value?

YES - Check connectors for looseness, poor connection, bending, corrosion, contamination. deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.

NO - Substitute with a known-good Driver Direction actuator and check for proper operation. If the problem is corrected, replace Driver air Direction actuator and then go to "Verification of Vehicle Repair" procedure.

VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verifying that the fault has been corrected.
1. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode.
2. Using scantool, Clear DTC.
3. Operate the vehicle within DTC Enable conditions in General information.
4. Are any DTCs present?

YES - Go to the applicable troubleshooting procedure.

NO - System is performing to specification at this time.