Diagnostic Method

< Timer diagnosis >

Start the count up operation of counters in ECM and in soaking timer IC when the engine is started.

Judge as timer malfunction if the difference between the counter in ECM and counter in soaking timer IC exceeds the allowable limit when the ignition switch is OFF.

Fig 1: ECM Monitor Output Waveforms

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

JUDGMENT VALUE

Malfunction Criteria	Threshold Value
\|osoaktimcpu - osoaktimic\|/osoaktimcpu	> 0.24
osoaktimcpu = Counter in ECM
osoaktimic = Counter in soaking timer IC

< Full count diagnosis >

Reset the counter in soaking timer IC and start the count up operation.

Judge as full count diagnosis malfunction if counter in soaking timer IC is not $3FF (1023 count) after 4 seconds.

Fig 2: Soaking Timer IC Waveforms

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

JUDGMENT VALUE

Malfunction Criteria	Threshold Value
osoakfcntic	$3FF (1023 count)
osoakfcntic = Counter in soaking timer IC

< Soaking timer IC setting diagnosis >

When setting the activation setting time to soaking timer IC, compare the writing value to soaking timer IC with read out value. Judge as malfunction if the values do not match 3 times in a row.

Fig 3: Soaking Timer IC Waveforms

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

JUDGMENT VALUE

Malfunction Criteria	Threshold Value
Writing value and read out value when setting the soaking timer	Unmatch

< Timer diagnosis (during soaking) >

Wake-up at the predetermined interval until 5 or 7 or 9.5 hours have passed after the ignition switch is OFF, and compare the counter in soaking timer IC with the counter in ECM.

Judge as malfunction if the counter in soaking timer IC is counted up to maximum value (1023 count) when the counter in ECM is 1636 ms, or if the counter in soaking timer IC is not counted up to maximum value (1023 count) when the counter in ECM is 2456 ms.

Fig 4: Timer Diagnosis Waveforms (During Soaking)

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

JUDGMENT VALUE

Malfunction Criteria	Threshold Value
When any one of the followings is established:
All of the following conditions are established.
Counter in ECM	≤ 1636 ms
Counter in soaking timer IC	= $3FF (1023 count)
All of the following conditions are established.
Counter in ECM	≥ 2456 ms
Counter in soaking timer IC	$3FF (1023 count)

< Wake-up diagnosis >

Store the number of wake-up activation when the ECM wakes up by the soaking timer IC.

Next time when the ignition switch is ON, if the number of wake-up activation does not reach the predetermined value even though the counter in soaking timer IC operates 1 hour or more, judge as wake-up malfunction.

Fig 5: ECM Wake-Up Activation Waveforms

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

JUDGMENT VALUE

Malfunction Criteria	Threshold Value
Number of wake-up	Wake-up indication count

Judge as NG when the following conditions are established.

JUDGMENT VALUE

Malfunction Criteria	Threshold Value
Ignition switch	ON
Driving cycle	Completed
When any one of the followings is established:
Timer diagnosis	NG
Full count diagnosis	NG
Soaking timer IC setting diagnosis	NG
Timer diagnosis (during soaking)	NG
Wake-up diagnosis	NG

Time Needed for Diagnosis: Approx. 5 - 9.5 hours

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