INTRODUCTION TO IMMOBILIZER SYSTEM DIAGNOSIS
| CAUTION | The encrypted code should always be re-registered when replacing the immobilizer-ECU. |
The immobilizer system consists of the ignition key, the key ring antenna, the immobilizer-ECU, and the engine control module. If the engine cannot be started by using a registered ignition key, one of these components may be defective. If the immobilizer system has immobilized the engine, MFI system DTC P0513 will be output. In this case, observe the immobilizer system troubleshooting.
CIRCUIT OPERATION
The ignition key is powered by the ignition key ring antenna. The ignition key then sends an encrypted code. The ignition key ring antenna receives the encrypted code, and determines if the ignition key is registered.
The Immobilizer-ECU is energized by the MFI relay when the ignition switch is turned "ON". The ECM transmits a signal from scan tool MB991958 to the immobilizer-ECU as it is. In the same way, a signal from the immobilizer-ECU is also transmitted to scan tool MB991502 or MB991958 as it is.
TECHNICAL DESCRIPTION (COMMENT)
- This malfunction may be caused by a defective immobilizer-ECU, ECM, or a defect in the communication line between the immobilizer-ECU and ECM. If this malfunction appears when the MFI system and scan tool MB991958 can communicate each other, MFI system DTC P0513 will reset.
- If the MFI system is normal, the MFI relay can be determined as normal. In addition, if the MFI system and scan tool MB991502 or MB991958 can communicate each other, the circuits between the data link connector and the ECM can determined as normal. NOTE: If this malfunction appears, MFI system DTC P0513 will be output.
The ignition key transponder or the immobilizer-ECU is suspected to be defective.
TECHNICAL DESCRIPTION
If the engine cranks, but does not start, an MFI system problem may exist in addition to a malfunctioning immobilizer system. The engine will not start if the ignition key has not been properly registered.
If the requirements for starting the engine are not satisfied, the immobilizer-ECU flashes the immobilizer indicator for 30 seconds.
The immobilizer indicator light or a malfunction of the combination meter or immobilizer-ECU.
POINTS TO NOTE DURING OPERATION
If none of the functions can be used, check the diagnostic trouble codes, and after carrying out any necessary repairs, repeat the operation.
If an incorrect password is input five times in a row, the immobilizer-ECU judges that an unauthorized operation is being attempted. Start-prevention mode will be set, and engine operation will stop and all special functions will be disabled. If the ignition switch is turned to "ON" position and left in that position for approximately 20 minutes, "Unauthorized operation, start-prevention mode" will be cancelled.