Keyless Operation System (KOS)

DTC B1A10: Keyless/KOS Key1 Low Battery
DTC B1A11: Keyless/KOS Key2 Low Battery
DTC B1A12: Keyless/KOS Key3 Low Battery
DTC B1A13: Keyless/KOS Key4 Low Battery

CAUTION: When replacing the ECU, always check that the communication circuit is normal.

DIAGNOSTIC FUNCTION
If KOS-ECU receives the keyless operation key low battery voltage signal, KOS-ECU sets the DTC No.B1A10, B1A11, B1A12, or B1A13.

JUDGEMENT CRITERIA
- B1A10: If KOS-ECU receives the keyless operation key 1 (the first keyless operation key registered with KOS-ECU) low battery voltage signal in five consecutive times, it is judged as abnormal.
- B1A11: If KOS-ECU receives the keyless operation key 2 (the second keyless operation key registered with KOS-ECU) low battery voltage signal in five consecutive times, it is judged as abnormal.
- B1A12: If KOS-ECU receives the keyless operation key 3 (the third keyless operation key registered with KOS-ECU) low battery voltage signal in five consecutive times, it is judged as abnormal.
- B1A13: If KOS-ECU receives the keyless operation key 4 (the fourth keyless operation key registered with KOS-ECU) low battery voltage signal in five consecutive times, it is judged as abnormal.

PROBABLE CAUSES
- Malfunction of the keyless operation key battery
- Malfunction of the keyless operation key
- Malfunction of KOS-ECU

DIAGNOSTIC PROCEDURE

STEP 1. Replace the battery in the keyless operation key and recheck the diagnostic trouble code.

Replace the battery of the keyless operation key for which the DTC is set, and check whether the DTC is reset.

1. Replace the battery of the keyless operation key for which the DTC is set.
2. Erase the DTC.
3. Turn the ignition switch from the LOCK (OFF) position to the ON position.
4. Lock or unlock the keyless operation key.
5. Check if the DTC is set.

Q: Is the DTC set?

YES : Go to Step 2.

NO : The diagnosis is complete (Discharged battery).

STEP 2. Replace the keyless operation key and recheck the diagnostic trouble code.

Replace the keyless operation key for which the DTC is set with a new one, register the key ID and keyless operation key ID and check whether the DTC is reset.

1. Erase the DTC.
2. Turn the ignition switch from the LOCK (OFF) position to the ON position.
3. Check if the DTC is set.

Q: Is the DTC set?

YES : Replace KOS-ECU and register the ID codes.

NO : The diagnosis is complete.