B1250

B1250

Component Location:

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:

Schematic Diagram:

Signal Waveform:

Monitor Scantool Data
1. Connect scantool to Data Link Connector (DLC).
2. Engine "ON".
3. Monitor the "DR DIRECTION POTENTIO" parameter on the scantool. While operating mode switch.






4. Are the DTC B1250 present and is parameter of "DR DIRECTION POTENTIO" fixed?
- Parameter of "DR DIRECTION POTENTIO" will be fixed at 100% (or any value above 90%), or 0% (or any value below 10%), if there is any fault in DR Direction actuator.

YES
a. Go to "Inspection & Repair" procedure.

NO
a. Fault is intermittent caused by poor contact in the sensor's and/or A/C control unit's connector or was repaired and A/C control unit memory was not cleared. Thoroughly 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.

Terminal and Connector 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
a. Repair as necessary and go to "Verification Vehicle Repair" procedure.

NO
a. Go to "W/Harness Inspection" procedure.

Signal Circuit Inspection
1. Check for short in harness
1. Ignition "OFF".
2. Disconnect DR Direction potentiometer.
3. Measure resistance between terminal "5" and "4" of DR Direction potentiometer.

Specification : Approx. Infinite ohms






4. Is the measured resistance within specifications?

YES
a. Go to "Ground circuit Inspection" procedure.

NO
a. Check for short to power harness in signal harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.

Ground Circuit inspection
1. Check for open in ground harness
1. Ignition "OFF".
2. Disconnect DR Direction Actuator.
3. Measure resistance between terminal "3" of DR Direction Actuator and chassis ground.

Specification : Approx. 0 ohm






4. Is the measured resistance within specifications?

YES
a. Go to "Component Inspection" procedure.

NO
a. Check for open in ground harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.

Component Inspection
1. Check DR Direction Actuator.
1. Check actuator motor
1. Ignition "OFF".
2. Disconnect DR Direction Actuator.
3. Connect (+) terminal of battery to terminal 1 of Direction Actuator and (-) terminal to terminal 2
4. Verify that the temperature actuator operates to the DEF or Vent position






5. Dose the actuator work properly?

YES
a. Go to "Check potentiometer" procedure.

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

2. Check actuator potentiometer
1. Ignition "ON".
2. Connect DR Direction Actuator.
3. Measure voltage between terminal "4" and "3" of DR Direction Actuator while operating the temp switch.

Specification : Refer the specifications in fig 3)






4. Is the measured voltage within specifications in fig 3)?

YES
a. 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
a. Substitute with a known-good actuator and check for proper operation. If the problem is corrected, replace actuator and then go to "Verification of Vehicle Repair" procedure.

Verification of Vehicle Repair
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scantool and select "Diagnostic Trouble Codes (DTCs)" mode and then clear DTC.
2. Operate the vehicle and monitor the DTC on the scantool.
3. Are any DTCs present?

YES
a. Go to the applicable troubleshooting procedure.

NO
a. System is performing to specification at this time.