Subaru Legacy 2003 Service Manual page 888

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
4 CHECK HARNESS BETWEEN ENGINE
COOLANT TEMPERATURE SENSOR AND
ECM CONNECTOR.
1) Turn ignition switch to OFF.
2) Measure resistance of harness between
engine coolant temperature sensor connec-
tor and engine ground.
Connector & terminal
(E8) No. 2 — Engine ground:
Is the measured value less than the speci-
fied value?
5 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
1) Remove engine coolant temperature sen-
sor.
2) Immerse sensor in approx. 20°C (68°F)
water.
NOTE:
Prevent water from entering into terminal part
of the sensor.
3) Measure resistance between engine cool-
ant temperature sensor terminals.
Terminals
No. 1 — No. 2:
Is the measured value within the specified
value?
6 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
1) Raise temperature up to approx. 80°C
(176°F).
CAUTION:
Be careful not to burn yourself.
2) Measure resistance between engine cool-
ant temperature sensor terminals.
Terminals
No. 1 — No. 2:
Is the measured value within the specified
value?
Value
5 Ω
2 — 3 kΩ
0.35 — 0.4 kΩ
EN(H4SOw/oOBD)-69
ENGINE (DIAGNOSTICS)
Yes
Go to step 5. Repair harness
and connector.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and engine
coolant tempera-
ture sensor con-
nector
• Poor contact in
engine coolant
temperature sen-
sor connector
• Poor contact in
ECM connector
• Poor contact in
coupling connector
(B21)
• Poor contact in
sensor ground
joint connector
(B83)
Go to step 6. Replace engine
coolant tempera-
ture sensor.
Go to step 7. Replace engine
coolant tempera-
ture sensor.
No