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: Main Relay General Driving Cycle Graph

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria	Threshold Value
\| (ECM counter) - (Soak timer IC counter) \|	> 0.24
/ECM counter

< 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: Main Relay Full Count Diagnosis Curve

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria	Threshold Value
Soak timer IC counter	$3FF (1023 count)

< 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: Main Relay Soaking Timer IC Setting Diagnosis Curve

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria	Threshold Value
Value commanded by the ECM	Value received by the soak timer IC

< 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 counts) when the counter in ECM is 1637 ms, or if the counter in soaking timer IC is not counted up to maximum value (1023 counts) when the counter in ECM is 2455 ms.

Fig 4: Timer Diagnosis Graph (During Soaking)

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria	Threshold Value
Soak timer IC counter when ECM counter	≤ 1.636 sec = 1023 count
Soak timer IC counter when ECM counter	≥ 2.456 sec 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: Wake-Up Diagnosis Pattern

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria	Threshold Value
Number of wake-up function commanded from ECM to Soak-timer IC	Number of actual wake-up ECM

Time Needed for Diagnosis: Approx. 5 - 9.5 hours

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