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 : B1230 (A-A4)
DTC B1230 or DTC screen A-A4 : A Short in the Sunlight Sensor Circuit
| DTC Description | DTC |
|---|---|
| B1230 A short in the sunlight sensor circuit |
DTC (AC)
- Problem verification
-1. Clear the DTC with the HDS.
-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 B1230 A short in the sunlight sensor circuit Is DTC B1230 or screen A-A4 indicated?
YES
Go to step 2.
NO
Intermittent failure. Check for loose wires or poor connections on the sunlight sensor circuit.
- Shorted wire check (TSUN line)
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Disconnect the following connectors.
Climate control unit connector A (28P) Sunlight sensor 2P connector (with automatic wiper) Sunlight sensor 5P connector (without automatic wiper) -3. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Climate control unit connector A (28P): disconnected Sunlight sensor 2P connector (with automatic wiper): disconnected Sunlight sensor 5P connector (without automatic wiper): disconnected Test circuit TSUN Test point 1 Climate control unit connector A (28P) No. 14 (YEL) Test point 2 Body ground Is there continuity?
YES
Repair a short to ground in the wire between the climate control unit and the sunlight sensor.
NO
The TSUN wire is not shorted. Go to step 3.
- Shorted wire check (TSUN line to SENSOR COM line)
-1. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Climate control unit connector A (28P): disconnected Sunlight sensor 2P connector (with automatic wiper): disconnected Sunlight sensor 5P connector (without automatic wiper): disconnected Test circuit TSUN, SENSOR COM Test point 1 Climate control unit connector A (28P) No. 14 (YEL) Test point 2 Climate control unit connector A (28P) No. 27 (WHT) Is there continuity?
YES
Repair a short in the wires between the climate control unit and the sunlight sensor.
NO
The TSUN wire to SENSER COM wire are not shorted. Go to step 4.
- Sunlight sensor check
-1. Reconnect climate control unit connector A (28P) .
-2. Test the sunlight sensor .
Is the sunlight sensor OK?
YES
Replace the climate control unit .
NO
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.