Subaru Legacy 2004 Service Manual page 2567

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AUTOMATIC TRANSMISSION (DIAGNOSTICS)
AG:DTC P1601 TCM COMMUNICATION MALFUNCTION
DTC DETECTING CONDITION:
Communication does not complete between control valve memory box.
TROUBLE SYMPTOM:
Shifting quality malfunction
WIRING DIAGRAM:
Step
1 CHECK POOR CONTACT OF TRANSMIS-
SION CONNECTOR.
Check loose connection on TCM connector
(B54).
2 CHECK DTC OF TCM.
B54
TCM
B11
T5
TRANSMISSION
Is there poor contact on con-
nector?
Is DTC of oil pressure switch
detected?
5AT(diag)-108
Check Yes
Go to step 2.
Perform the diag-
nosis according to
DTC.
B54
1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16 17 18
19 20 21 22 23 24
B11
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
17 18 19 20
T5
1 2 3 4 5 6
7 8 9 10 11 12 13 14 15 16
AT-01800
No
Connect it
securely.
Go to step 3.