#
ON-BOARD DIAGNOSTIC SYSTEM FUNCTION (ELECTRIC POWER STEERING)

BHE060201038T02

## Malfunction Detection Function

• The malfunction detection function detects malfunctions in the input/output signal system of the EPS control module when the ignition switch is at the ON position or driving the vehicle.

• When the ignition switch is turned to the ON position, the EPS warning light illuminates as shown in the diagram to inspect for open circuits in the light.

1 | When the period until engine rotation is determined is 2.4±0.2 s or less
2 | When the period until engine rotation is determined is 2.4±0.2 s or more
3 | Ignition switch
4 | Engine rotation determined
5 | EPS warning light
6 | On
7 | Off
8 | Engine rotation
9 | Engine stopped
10 | 2.4±0.2 s or less
11 | 250 ms
12 | 2.4±0.2 s
13 | Time until engine is determined to be rotating

## Malfunction Display Function

• When the malfunction detection function detects a malfunction, the EPS warning light illuminates to advise the driver. Using the external tester communication function, DTCs can be output to the DLC-2 via the CAN communication line. At the same time, malfunction detection results are sent to the memory and fail-safe functions.

## Memory Function

• The memory function stores DTCs for malfunctions in input/output signal systems. With this function, once a DTC is stored it is not cleared after the ignition switch has been turned off (LOCK position), even if the malfunctioning signal system has returned to normal.

• Since the EPS control module has a built-in non-volatile memory, DTCs are not cleared even if the battery is removed. Therefore, it is necessary to clear the memory after performing repairs. Refer to the Workshop Manual for the DTC clearing procedure.

## Fail-safe Function

• When the malfunction detection function determines a malfunction, the EPS warning light illuminates to advise the driver. At this time, the fail-safe function controls the system as shown in the DTC table.

DTC TABLE

System malfunction location | DTC | Fail-safe function
--- | --- | ---
EPS warning light illumination status | Control status
Battery power supply | B1318 | Illuminated | Control suspended
EPS control module | B1342 | Illuminated | Control suspended
EPS system (neutral position setting not performed) | B2141 | Illuminated | Control available
Torque sensor | B2278 | Illuminated | Control suspended
EPS motor | C1099 | Illuminated | Control suspended
CAN bus communication error | U0073 | Illuminated*1 | Control available*2
CAN communication error | U1900 | Illuminated*1 | Control available*2
CAN communication error | U2023 | Illuminated*1 | If there is an irregularity only in the vehicle speed data: Control available*2 If there is any other irregularity: Control available*3

  *1 :
Illuminates after switching to fail mode.
  *2 :
Switches to fail mode (controlled by assist torque to allow safe driving).
  *3 :
If a malfunction is detected in the engine speed signal before the engine is started, assist control is not started up.