Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC B1240 (F-B2): A Problem in the Mode Control Motor Circuit, Linkage, Door, or Motor
DTC B1240 or DTC screen F-B2
| DTC Description | DTC |
|---|---|
| B1240 A Problem in the Mode Control Motor Circuit, Linkage, Door, or Motor |
DTC (AC)
- Problem verification
-1. Clear the DTCs with the HDS.
- 2. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.
- 3. Do the Self-Diagnostic Function with the HDS or the climate control unit.
- 4. Check for DTCs.
DTC Description DTC B1240 A Problem in the Mode Control Motor Circuit, Linkage, Door, or Motor Is DTC B1240 or screen F-B2 indicated?
YES
Go to step 2.
NO
Intermittent failure. Check for loose wires or poor connections on the mode control motor circuit.
- Open wire check (SENSOR COM line)
-1. Turn the vehicle to the OFF (LOCK) mode.
- 2. Disconnect the following connector.
Mode control motor 7P connector - 3. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Mode control motor 7P connector: disconnected Test point 1 Mode control motor 7P connector No. 1 Test point 2 Body ground Is there continuity?
YES
The SENSOR COM wire is OK. Go to step 3.
NO
Repair an open in the wire between the climate control unit and the mode control motor.
- Open wire check (MODE MTR DEF line)
-1. Disconnect the following connector.
Climate control unit connector A (40P) - 2. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Climate control unit connector A (40P): disconnected Mode control motor 7P connector: disconnected Test point 1 Climate control unit connector A (40P) No. 7 - Refer to: Climate Control Unit Connector for Inputs and Outputs (With Auto Idle Stop System) (2015-17) or Climate Control Unit Connector for Inputs and Outputs (Without Auto Idle Stop System) (2015-17) or Climate Control Unit Connector for Inputs and Outputs (Without Auto Idle Stop System) (2018-19), or Climate Control Unit Connector for Inputs and Outputs (With Auto Idle Stop System) (2018-19) Test point 2 Mode control motor 7P connector No. 6 Is there continuity?
YES
The MODE MTR DEF wire is not open. Go to step 4.
NO
Repair an open in the wire between the climate control unit and the mode control motor.
- Open wire check (MODE MTR VENT line)
-1. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Climate control unit connector A (40P): disconnected Mode control motor 7P connector: disconnected Test point 1 Climate control unit connector A (40P) No. 8 - Refer to: Climate Control Unit Connector for Inputs and Outputs (With Auto Idle Stop System) (2015-17) or Climate Control Unit Connector for Inputs and Outputs (Without Auto Idle Stop System) (2015-17) or Climate Control Unit Connector for Inputs and Outputs (Without Auto Idle Stop System) (2018-19), or Climate Control Unit Connector for Inputs and Outputs (With Auto Idle Stop System) (2018-19) Test point 2 Mode control motor 7P connector No. 7 Is there continuity?
YES
The MODE MTR VENT wire is not open. Go to step 5.
NO
Repair an open in the wire between the climate control unit and the mode control motor.
- Shorted wire check (MODE MTR DEF line)
-1. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Climate control unit connector A (40P): disconnected Mode control motor 7P connector: disconnected Test point 1 Climate control unit connector A (40P) No. 7 - Refer to: Climate Control Unit Connector for Inputs and Outputs (With Auto Idle Stop System) (2015-17) or Climate Control Unit Connector for Inputs and Outputs (Without Auto Idle Stop System) (2015-17) or Climate Control Unit Connector for Inputs and Outputs (Without Auto Idle Stop System) (2018-19), or Climate Control Unit Connector for Inputs and Outputs (With Auto Idle Stop System) (2018-19) Test point 2 Body ground Is there continuity?
YES
Repair a short to ground in the wire between the climate control unit and the mode control motor.
NO
The MODE MTR DEF is not shorted. Go to step 6.
- Shorted wire check (MODE MTR VENT line)
-1. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Climate control unit connector A (40P): disconnected Mode control motor 7P connector: disconnected Test point 1 Climate control unit connector A (40P) No. 8 - Refer to: Climate Control Unit Connector for Inputs and Outputs (With Auto Idle Stop System) (2015-17) or Climate Control Unit Connector for Inputs and Outputs (Without Auto Idle Stop System) (2015-17) or Climate Control Unit Connector for Inputs and Outputs (Without Auto Idle Stop System) (2018-19), or Climate Control Unit Connector for Inputs and Outputs (With Auto Idle Stop System) (2018-19) Test point 2 Body ground Is there continuity?
YES
Repair a short to ground in the wire between the climate control unit and the mode control motor.
NO
The MODE MTR VENT wire is not shorted. Go to step 7.
- Shorted wire check (MODE MOTOR DEF line to MODE MOTOR VENT line)
-1. Check for continuity between test points 1 and 2.
Is there continuity?
YES
Repair a short in the wires between the climate control unit and the mode control motor.
NO
The MODE MOTOR DEF wire to MODE MOTOR VENT wire are OK. Go to step 8.
- Mode control motor check
-1. Test the mode control motor.
Is the mode control motor OK?
YES
Replace the climate control unit .
NO
Replace the mode control motor , or repair the mode control linkage or door.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.