DESCRIPTION If the
communication line (IMI - EFIO) between the ECM and certification ECU
(smart key ECU assembly) is stuck high, the ECM will store this DTC. |
DTC No. | Detection Item |
DTC Detection Condition | Trouble Area |
Note | | B279A12 |
Engine Immobiliser System Circuit Short to Battery |
The
communication line (IMI - EFIO) between the ECM and certification ECU
(smart key ECU assembly) is stuck high. (1 trip detection logic*) |
- Certification ECU (smart key ECU assembly)
- ECM
- Wire harness or connector
| DTC output confirmation operation:
- Turn the engine switch on (IG) and wait 6 seconds.
|
- *: Only output while a malfunction is present.
Vehicle Condition and Fail-safe Operation when Malfunction Detected |
Vehicle Condition when Malfunction Detected |
Fail-safe Operation when Malfunction Detected | |
Engine cannot be started | Engine cannot be started | Related Data List and Active Test |
DTC No. | Data List and Active Test | |
B279A12 | - | WIRING DIAGRAM
 CAUTION / NOTICE / HINT
NOTICE:
- When using the Techstream with the engine switch off, connect the
Techstream to the DLC3 and turn a courtesy light switch on and off at
intervals of 1.5 seconds or less until communication between the
Techstream and the vehicle begins. Then select the vehicle type under
manual mode and enter the following menus: Body Electrical / Smart Key.
While using the Techstream, periodically turn a courtesy light switch on
and off at intervals of 1.5 seconds or less to maintain communication
between the Techstream and the vehicle.
- The smart key system (for Start Function, Gasoline Model) uses the LIN
communication system and CAN communication system. Inspect the
communication function by following How to Proceed with Troubleshooting.
Troubleshoot the smart key system (for Start Function, Gasoline Model)
after confirming that the communication systems are functioning
properly.
Click here 
- Before replacing the ECM or certification ECU (smart key ECU assembly), refer to Registration.
Click here
- After performing repairs, confirm that no DTCs are output by performing "DTC Output Confirmation Operation".
HINT: When DTC
B279A12 and a certification ECU (smart key ECU assembly) DTC are output
simultaneously, first perform troubleshooting for the certification ECU
(smart key ECU assembly) DTC. PROCEDURE
| 1. |
CHECK CONNECTION OF CONNECTOR | (a) Turn the engine switch off.
(b) Check that the connectors are properly connected to the ECM and certification ECU (smart key ECU assembly).
OK: Connectors are properly connected.
| NG |
 | CONNECT CONNECTORS PROPERLY |
|
OK |
 | |
| 2. |
CHECK WHETHER ENGINE STARTS | (a) Check that the engine starts.
OK: Engine starts normally.
| OK |
| USE SIMULATION METHOD TO CHECK |
|
NG | |
| |
| (a) Measure the voltage according to the value(s) in the table below.
Standard Voltage: |
Tester Connection | Condition |
Specified Condition | |
A10-4 (EFIO) - Body ground |
Engine switch on (IG) |
11 to 14 V | |
 |
|
*a | Component with harness connected (Certification ECU (Smart Key ECU Assembly)) | | |
| NG |
| GO TO STEP 5 |
|
OK | |
| |
| 4. |
CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (TERMINAL EFIO) |
(a) Connect the A10 certification ECU (smart key ECU assembly) connector.
(b) Using an oscilloscope, check the waveform.
|
*a | Component with harness connected
(Certification ECU (Smart Key ECU Assembly)) |
*b | Waveform | |
*c | Approximately 160 ms. |
*d | Approximately 270 ms. |
OK: |
Tester Connection | Condition |
Tool Setting | Specified Condition | |
A10-4 (EFIO) - Body ground |
Engine switch turned on (IG) using registered electrical key transmitter sub-assembly |
2 V/DIV., 500 ms./DIV. |
Pulse generation (See waveform) |
| OK |
| REPLACE ECM |
| NG |
| REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) |
| 5. |
CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - ECM) |
(a) Disconnect the A18 ECM connector. (b) Measure the resistance according to the value(s) in the table below.
Standard Resistance: |
Tester Connection | Condition |
Specified Condition | |
A10-4 (EFIO) - A18-59 (IMI) |
Always | Below 1 Ω |
| OK |
| REPLACE ECM |
| NG |
| REPAIR OR REPLACE HARNESS OR CONNECTOR | | 
