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ON-BOARD DIAGNOSTIC SYSTEM FUNCTION [ELECTRONIC 4WD CONTROL SYSTEM]

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## Failure detection function

• The failure detection function detects malfunctions in the input/output signal systems of the 4WD CM and displays them when the ignition key is at the ON position.
• When the ignition key is turned to the ON position, the 4WD CM system begins operation, and the 4WD warning light illuminates for 3 seconds while the function checks for open circuits. At the same time the function monitors the condition of the power supply voltage and checks for internal malfunctions.
• Then, once the system is running, the function checks the operating conditions of the 4WD solenoid and the differential oil temperature sensor at regular intervals to determine whether there is any malfunction.
• If any malfunction is detected during these diagnostic tests, the warning light illuminates according to the malfunction to alert the driver. Also, a DTC is output to DLC-2 via the CAN line. Also, at the same time the failure detection result is sent to the memory and fail-safe functions.

## Memory function

• This function stores DTCs for malfunctions of the input/output signal systems as determined by the failure detection function. Once a DTC is stored, it is not cleared even if the input/output signal system malfunction returns to normal when the ignition key is turned to the LOCK position (engine OFF).
• Since DTCs are stored in the non-volatile memory inside the 4WD CM, they are not cleared even if the battery is disconnected. Therefore, it is necessary to clear the memory when maintenance has been completed. For clearing DTCs, refer to the procedures in the Workshop Manual.

## Fail-safe function

• When the failure detection function determines that there is a malfunction, the 4WD warning light illuminates to alert the driver. At this time, the fail-safe function suspends control or takes other measures to ensure that driving stability is not lost.

L3

X: Available

DTC | Malfunction location | 4WD warning light condition | DTC stored in memory | Control condition
--- | --- | --- | --- | ---
P1887 | System wiring | Illuminated | X | Stop
P1888 | Differential oil temperature sensor | Illuminated | X | Stop
U0100 | PCM communication system | Illuminated | X | Stop
U0101 | TCM communication system | Illuminated | X | Stop
U0121 | DSC communication system | Illuminated*1 | X | Stop*2

L3 Turbo

X: Available

DTC | Malfunction location | 4WD warning light condition | DTC stored in memory | Control condition
--- | --- | --- | --- | ---
P1887 | System wiring | Illuminated | X | Stop
P1888 | Differential oil temperature sensor | Illuminated | X | Stop
U0073 | CAN system communication error | Illuminated | X | Stop
U0100 | PCM communication system | Illuminated | X | Stop
U0121 | DSC communication system | Illuminated*1 | X | Stop*2

  *1 :
Does not illuminate when only the coupling torque request signal from the DSC HU/CM cannot be received.
  *2 :
Only integrated DSC control is prohibited when only the coupling torque request signal from the DSC HU/CM cannot be received.