Subaru Forester 2004 Service Manual page 179

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTIC)
Step
1 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to OFF.
2) Connect the test mode connector.
3) Turn the ignition switch to ON.
4) While operating the radiator fan relay, mea-
sure voltage between ECM and chassis ground.
NOTE:
Radiator fan relay operation can be executed
using Subaru Select Monitor. For procedure,
refer to "Compulsory Valve Operation Check
Mode". <Ref. to EN(H4DOTC 2.5)-43, Compul-
sory Valve Operation Check Mode.>
Connector & terminal
(B135) No. 24 (+) — Chassis ground (
(B135) No. 25 (+) — Chassis ground (
2 CHECK SHORT CIRCUIT IN RADIATOR FAN
RELAY CONTROL CIRCUIT.
1) Turn the ignition switch to OFF.
2) Remove the main fan relay, sub fan relay
and fan mode relay.
3) Disconnect the test mode connectors
4) Turn the ignition switch to ON.
5) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B135) No. 24 (+) — Chassis ground (
(B135) No. 25 (+) — Chassis ground (
3 CHECK FAN RELAY.
1) Turn the ignition switch to OFF.
2) Remove the fan relay.
3) Measure the resistance between fan relay
terminals.
Terminals
No. 30 — No. 31 (Main fan relay)
No. 28 — No. 29 (Sub fan relay)
4 CHECK FAN MODE RELAY.
1) Remove the fan mode relay.
2) Measure the resistance between fan mode
relay terminals.
Terminals
No. 8 — No. 9: (Fan mode relay)
5 CHECK POOR CONTACT.
Check poor contact in ECM connector.
AW:DTC P0700 TRANSMISSION CONTROL SYSTEM (MIL REQUEST)
NOTE:
For the diagnostic procedure, refer to AT section. <Ref. to 4AT(H4SO)-2, PROCEDURE, Basic Diagnostic
Procedure.>
Check
Does the voltage vary between
0 — 10 V?
−
):
−
):
Is the voltage more than 10 V? Repair battery
−
):
−
):
Is the resistance less than 1
Ω?
Is the resistance less than 1
Ω?
Is there poor contact in ECM
connector?
EN(H4DOTC 2.5)-178
Yes
Even if the mal- Go to step 2.
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time. In this
case, repair poor
contact in ECM
connector.
Go to step 3.
short circuit in radi-
ator fan relay con-
trol circuit. After
repair, replace the
ECM. <Ref. to
FU(H4DOTC 2.5)-
41, Engine Con-
trol Module
(ECM).>
Replace the fan Go to step 4.
relay and ECM.
<Ref. to
FU(H4DOTC 2.5)-
41, Engine Con-
trol Module
(ECM).>
Replace the fan Go to step 5.
mode relay and
ECM. <Ref. to
FU(H4DOTC 2.5)-
41, Engine Con-
trol Module
(ECM).>
Repair the poor Replace the ECM.
contact in ECM <Ref. to
connector. FU(H4DOTC 2.5)-
41, Engine Con-
trol Module
(ECM).>
No