Diagnostic Method

< Case #1 >

Judge as abnormal in engine off timer or power supply IC timer when the difference between wake-up request time and power supply IC timer exceeds the threshold value.

When the sub CPU is faulty, wake-up timing is either advancing or retarding compared with normal timing.

Fig 1: Power Supply IC And Sub CPU Diagnosis Chart (Case #1)

Courtesy of SUBARU OF AMERICA, INC.

Processed in order Step 1 through Step 3.

Judge as NG when the following conditions are established.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria	Threshold Value
\|(Power supply IC timer) - (Wake-up request time)\|/Wake-up request time	> 0.24

Time Needed for Diagnosis: Less than 1 second

Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.

< Case #2 >

Judge as abnormal in engine off timer when the power supply IC timer exceeds the wake-up request time before wake up.

When case #1 is not performed, perform case #2.

Fig 2: Power Supply IC And Sub CPU Diagnosis Chart (Case #2)

Courtesy of SUBARU OF AMERICA, INC.

Processed in order Step 1 through Step 3.

Judge as NG when the following conditions are established.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria	Threshold Value
{(Power supply IC timer) - (Wake-up request time)}/Wake-up request time	> 0.24

Time Needed for Diagnosis: Less than 1 second

Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.

< Case #3 >

Diagnose the communication error between main CPU and sub CPU.

Judge as NG when the wake-up time required from main CPU and the wake-up time received from sub CPU are different.

Fig 3: Power Supply IC And Sub CPU Diagnosis Chart (Case #3)

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria	Threshold Value
Wake-up time required by main CPU	Wake-up time sent back by sub CPU

Time Needed for Diagnosis: 2 seconds

Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.

< Case #4 >

Diagnose the communication error between main CPU and power supply IC.

Judge as NG when the signal required by main CPU and the signal received from power supply IC are different.

Fig 4: Power Supply IC And Sub CPU Diagnosis Chart (Case #4)

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria	Threshold Value
Signal required by main CPU	Signal received from power supply IC

Time Needed for Diagnosis: 2 seconds

Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.

< Case #5 >

On main CPU and sub CPU, there are two operation status: "normal mode" and "wake-up mode".

Perform diagnosis for CPU operation status abnormality by detecting the difference in operating status of main CPU and sub CPU.

Judge as NG when main CPU and sub CPU is different in operating status.

Fig 5: Power Supply IC And Sub CPU Diagnosis Chart (Case #5)

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria	Threshold Value
Operating status of main CPU	Operating status of sub CPU

Time Needed for Diagnosis: 2 seconds

Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.

< Case #6 >

Perform diagnosis for ignition switch status abnormality by detecting the difference in ignition switch status (ON or OFF) of main CPU and sub CPU.

Judge as NG when main CPU and sub CPU are different in ignition switch status.

Fig 6: Power Supply IC And Sub CPU Diagnosis Chart (Case #6)

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria	Threshold Value
Ignition switch status of main CPU	Ignition switch status of sub CPU

Time Needed for Diagnosis: 2 seconds

Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.