Subaru Legacy 2005 Service Manual page 2239

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
P: DTC P0748 PRESSURE CONTROL SOLENOID "A" ELECTRICAL
DTC DETECTING CONDITION:
Output signal circuit of line pressure linear solenoid is open or shorted.
TROUBLE SYMPTOM:
Excessive shift shock
WIRING DIAGRAM:
B11
3 4
1 2
5 6 7 8
9 10 11 12
14 15
13 16
17 18 19 20
Step
1 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from transmis-
sion and TCM.
3) Measure the resistance of harness
between TCM and transmission connector.
Connector & terminal
(B55) No. 19 — (B11) No. 2:
(B55) No. 20 — (B11) No. 1:
2 CHECK HARNESS CONNECTOR BETWEEN
TCM AND CHASSIS GROUND.
Measure the resistance of harness between
TCM connector and chassis ground.
Connector & terminal
(B55) No. 19 — Chassis ground:
(B55) No. 20 — Chassis ground:
3 CHECK LINE PRESSURE LINEAR SOLE-
NOID.
Measure the resistance between transmission
connector receptacle's terminals.
Connector & terminal
(T4) No. 1 — No. 2:
TRANSMISSION
B55
1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16 17 18 19 20 21
22 23 24 25 26 27 28 29 30 31
Is the resistance less than 1
Ω?
Is the resistance more than 1
MΩ?
Is the resistance 4 — 8 Ω?
4AT(diag)-67
AUTOMATIC TRANSMISSION (DIAGNOSTICS)
B55
TCM
B11
T4
AT2
LINE
PRESSURE
LINEAR
SOLENOID
AT2
1 2
3 4
Check Yes
Go to step 2. Repair the open
circuit of harness
between TCM and
transmission con-
nector.
Go to step 3. Repair the short
circuit of harness
between TCM and
transmission con-
nector.
Repair the TCM. Go to step 4.
<Ref. to 4AT-66,
Transmission Con-
trol Module
(TCM).>
AT-01486
No