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 B1575: Auto light sensor circuit malfunction (2015-17)
| DTC Description | DTC |
|---|---|
| B1575 Auto light sensor circuit malfunction |
DTC (MICU)
NOTE: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A - Refer to: Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC Checks (2015-17), or Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC Checks (2018-19) .
- Problem verification
-1. Clear the DTCs with the HDS.
- 2. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.
- 3. Check for DTCs with the HDS.
DTC Description DTC B1575 Auto light sensor circuit malfunction Is DTC B1575 indicated?
YES
Go to step 2.
NO
Intermittent failure, the system is OK at this time. Check for loose or poor connections.
- Determine possible failure area (automatic lighting sensor, others)
-1. Turn the vehicle to the OFF (LOCK) mode.
- 2. Disconnect the following connector.
Automatic lighting sensor 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 Automatic lighting sensor 5P connector: disconnected
Test point 1 Automatic lighting sensor 5P connector No. 5 Test point 2 Body ground Is there about 5V?
YES
The AUTO LT SIP wire is OK. Replace the automatic lighting sensor .
NO
Go to step 3.
- Open wire check (AUTO LT SIP line)
-1. Turn the vehicle to the OFF (LOCK) mode.
- 2. Disconnect the following connector.
Under-dash fuse/relay box connector N (20P) - 3. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Automatic lighting sensor 5P connector: disconnected
Under-dash fuse/relay box connector N (20P): disconnected
Test point 1 Automatic lighting sensor 5P connector No. 5 Test point 2 Under-dash fuse/relay box connector N (20P) No. 8 - Refer to: Exterior Lights (MICU) Input Test, or Exterior Lights (MICU) Input Test (With SH-AWD) Is there continuity?
YES
The AUTO LT SIP wire is OK. Faulty MICU; replace the under-dash fuse/relay box .
NO
Repair an open or high resistance in the wire.
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.