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 : B1234 (B-A2)
DTC B1234 or DTC screen B-A2 : A Short in the Air Mix Control Motor Circuit (Driver's)
NOTE: If other short circuit DTCs are indicated at the same time, there may be an open or short to body ground in the power (5 V) circuit.
| DTC Description | DTC |
|---|---|
| B1234 A short in the air mix control motor circuit (driver's) |
DTC (AC)
- Problem verification
-1. Clear the DTCs with the HDS. How to Clear DTCs
Clear DTCs
-2. Turn the vehicle to the OFF (LOCK) mode 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 B1234 A short in the air mix control motor circuit (driver's) Is DTC B1234 or screen B-A2 indicated?
YES
Go to step 2.
NO
Intermittent failure. Check for loose wires or poor connections on the driver's air mix control motor circuit.
- Open wire check (S5V line)
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Disconnect the following connector.
Driver's air mix control motor 5P connector -3. Turn the vehicle to the ON mode.
-4. Measure the voltage between test points 1 and 2.
Test condition Vehicle ON mode Driver's air mix control motor 5P connector: disconnected Test circuit S5V Test point 1 Driver's air mix control motor 5P connector No. 1 (BRN) Test point 2 Body ground Is there about 5 V?
YES
The S5V wire is OK. Go to step 3.
NO
Go to step 4.
- Determine possible failure area (driver's air mix control motor, others)
-1. Measure the voltage between test points 1 and 2.
Test condition Vehicle ON mode Driver's air mix control motor 5P connector: disconnected Test circuit AMD-P(DR) Test point 1 Driver's air mix control motor 5P connector No. 2 (BLU) Test point 2 Body ground Is there about 5 V?
YES
Replace the driver's air mix control motor .
NO
Go to step 6.
- Climate control unit check
-1. Measure the voltage between test points 1 and 2.
Test condition Vehicle ON mode Driver's air mix control motor 5P connector: disconnected Test circuit S5V Test point 1 Climate control unit connector B (36P) No. 2 (BRN) Test point 2 Body ground Is there about 5 V?
YES
Repair an open in the wire between the climate control unit and the driver's air mix control motor.
NO
Go to step 5.
- Shorted wire check (S5V line)
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Disconnect the following connector.
Climate control unit connector B (36P) -3. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Climate control unit connector B (36P): disconnected Driver's air mix control motor 5P connector: disconnected Test circuit S5V Test point 1 Climate control unit connector B (36P) No. 2 (BRN) Test point 2 Body ground Is there continuity?
YES
Repair a short to ground in the wire between the climate control unit and the driver's air mix control motor.
NO
The S5V wire is not shorted. Replace the climate control unit .
- Shorted wire check (AMD-P(DR) line)
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Disconnect the following connector.
Climate control unit connector B (36P) -3. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Climate control unit connector B (36P): disconnected Driver's air mix control motor 5P connector: disconnected Test circuit AMD-P(DR) Test point 1 Climate control unit connector B (36P) No. 20 (BLU) Test point 2 Body ground Is there continuity?
YES
Repair a short to ground in the wire between the climate control unit and the driver's air mix control motor.
NO
The AMD-P(DR) wire is not shorted. Replace the climate control unit .
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.