Subaru IMPREZA GD 2007 Series Manual page 2724

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Diagnostic Procedure with Diagnostic Trouble Code (DTC)
X: DTC P1718 CAN COMMUNICATION CIRCUIT
DIAGNOSIS:
Input signal circuit of TCM is open or shorted.
WIRING DIAGRAM:
ABS
CONTROL MODULE
B301
Step
1 CHECK DIAGNOSTIC CODE.
Check whether multiple DTCs appear under on-
board diagnostics test mode.
2 CHECK HARNESS CONNECTORS BE-
TWEEN TCM, ECM AND ABSCM.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from TCM, ECM
and ABSCM.
3) Measure the resistance of harness between
TCM, ECM and ABSCM connectors.
Connector & terminal
(B55) No. 17 — (B136) No. 35:
(B55) No. 17 — (B301) No. 11:
3 CHECK HARNESS CONNECTORS BE-
TWEEN TCM, ECM AND ABSCM.
Measure the resistance of harness between
TCM, ECM and ABSCM connectors.
Connector & terminal
(B55) No. 18 — (B136) No. 27:
(B55) No. 18 — (B301) No. 26:
4 CHECK HARNESS CONNECTORS BE-
TWEEN TCM, ECM AND ABSCM.
Measure the resistance of the harness between
TCM and chassis ground.
Connector & terminal
(B55) No. 17 — Chassis ground:
(B55) No. 18 — Chassis ground:
B55
TCM
26
11
B136
ECM
Do multiple DTCs appear?
Is resistance less than 1 Ω?
Is resistance less than 1 Ω?
Is the resistance 1 MΩ or
more?
4AT(D)(diag)-85
AUTOMATIC TRANSMISSION (DIAGNOSTICS)
1 2
7 8 9
17 18 19 20
28 29 30
1
12 13 14 15
Check Yes
Go to other DTC.
Go to step 3.
Go to step 4.
TCM, ECM or
ABSCM may be
defective.
(Replace and
check again.)
B55
B136
3 4 5 6
10 11 12 13 14 15 16
21 22 23 24 25 26 27
31 32 33 34 35
B301
2 3 4 5 6 7 8 9 10 11
16 17 18 19 20 21 22 23 24 25 26
AT-04992
No
Go to step 2.
Repair open circuit
of the harnesses
between TCM,
ECM and ABSCM,
or the poor contact
in the connectors.
Repair open circuit
of the harnesses
between TCM,
ECM and ABSCM,
or the poor contact
in the connectors.
Repair the short
circuit of harness
between TCM,
ECM and ABSCM.