Subaru Legacy 2003 Service Manual page 2322

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
3 CHECK HARNESS CONNECTOR BETWEEN
TCM AND ECM.
Measure the resistance of harness between
TCM connector and chassis ground.
Connector & terminal
(B54) No. 1 — Chassis ground:
Does the measured value exceed the specified
value?
4 PREPARE SUBARU SELECT MONITOR.
Do you have a Subaru Select Monitor?
5 CHECK INPUT SIGNAL FOR TCM.
1) Connect the connectors to TCM and ECM.
2) Start the engine and warm-up the transmis-
sion until ATF temperature is above 80°C
(176°F).
NOTE:
If ambient temperature is below 0°C (32°F),
drive the vehicle until ATF reaches its operating
temperature.
3) Idle the engine.
4) Measure the voltage between TCM con-
nector and chassis ground.
Connector & terminal
(B54) No. 1 (+) — Chassis ground ( − − − − ):
Is the measured value within the specified
range?
6 CHECK INPUT SIGNAL FOR TCM USING
SUBARU SELECT MONITOR.
1) Connect the connectors to TCM and ECM.
2) Connect the Subaru Select Monitor to data
link connector.
3) Start the engine and turn the Subaru Select
Monitor switch to ON.
4) Warm-up the engine until engine coolant
temperature is above 80°C (176°F).
5) Idle the engine.
6) Read the data of mass air flow sensor sig-
nal using Subaru Select Monitor.
•Display shows the mass air flow sensor signal
value sent from ECM.
Is the data of mass air flow sensor within
the specified range?
7 CHECK POOR CONTACT.
Is there poor contact in mass air flow sensor
signal circuit?
AUTOMATIC TRANSMISSION (DIAGNOSTICS)
Value
1 MΩ
Subaru Select Monitor is avail-
able.
0.9 — 1.4 V
0.9 — 1.4 V
There is poor contact.
AT-47
Yes
Go to step 4. Repair the short
circuit in harness
between TCM and
ECM connector.
Go to step 6. Go to step 5.
Even if the power Go to step 7.
indicator light
lights up, the cir-
cuit has returned
to a normal condi-
tion at this time. A
temporary poor
contact of the con-
nector or harness
may be the cause.
Repair harness or
connector in the
TCM and ECM.
Even if the power Go to step 7.
indicator light
lights up, the cir-
cuit has returned
to a normal condi-
tion at this time. A
temporary poor
contact of the con-
nector or harness
may be the cause.
Repair harness or
connector in the
TCM and ECM.
Repair the poor Replace TCM.
contact. <Ref. to AT-76,
Transmission Con-
trol Module
(TCM).>
No