Subaru Legacy 2003 Service Manual page 2321

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
AUTOMATIC TRANSMISSION (DIAGNOSTICS)
B: DTC 23 MASS AIR FLOW SIGNAL (TURBO MODEL)
DIAGNOSIS:
The input signal circuit of TCM from ECM is open or shorted.
TROUBLE SYMPTOM:
Excessive shift shock.
WIRING DIAGRAM:
B54
1 2 3 4 5 6 7
10 11 12 13 14 15 16 17 18
19 20 21 22 23 24
1 CHECK ENGINE GROUND TERMINALS AND
GROUND CIRCUIT OF ECM.
<Ref. to AT-52, DTC 31 THROTTLE POSI-
TION SENSOR, Diagnostic Procedure with
Diagnostic Trouble Code (DTC).>
Is there any trouble?
2 CHECK HARNESS CONNECTOR BETWEEN
TCM AND ECM.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from TCM and
ECM.
3) Measure the resistance of harness
between TCM and ECM connector.
Connector & terminal
(B54) No. 1 — (B135) No. 28:
Is the measured value less than the speci-
fied value?
B135
1 2 3 4 5 6
8 9
10 11 12 13 14 15 16 17 18 19
20 21 22 23 24 25
Step
B135 ECM
TCM
B54
7 8 9
26 27 28
Value
There is a trouble.
1 Ω
AT-46
Yes
Repair the ground Go to step 2.
terminal and/or
ground circuit of
ECM.
Go to step 3. Repair the open
circuit in harness
between TCM and
ECM connector.
AT-00574
No