DTC Troubleshooting: B1240 (M)

DTC indicator M or DTC B1240: A Problem in the Mode Control Linkage, Doors, or Motor Clear the DTC. Turn the ignition switch OFF, and then ON. Operate the climate control system is several modes. Check the DTCs. Is DTC M or B1240 indicated?
YES | - | Go to Step 5 .
NO | - | Intermittent failure.■
Test the mode control motor. Is the mode control motor OK?
YES | - | Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit .■
NO | - | Replace the mode control motor, or repair the mode control linkage or doors.■