Subaru Legacy 2002 Service Manual page 1877

DIAGNOSTIC PROCEDURE FOR NO-DIAGNOSTIC TROUBLE CODE (DTC)
Automatic Transmission (Diagnostics)
No.
1 CHECK FWD SWITCH.
2 CHECK FWD INDICATOR LIGHT.
1) Turn ignition switch to OFF.
2) Remove combination meter.
3) Remove FWD indicator light bulb from
combination meter.
3 CHECK HARNESS CONNECTOR
BETWEEN TCM AND FWD SWITCH.
1) Turn ignition switch to OFF.
2) Disconnect connector from TCM and FWD
switch.
3) Measure resistance of harness between
TCM and FWD switch connector.
Connector & terminal
(B55) No. 20 — (F67) No. 30:
4 CHECK HARNESS CONNECTOR
BETWEEN TCM AND FWD SWITCH.
Measure resistance of harness connector
between TCM and body to make sure that
circuit does not short.
Connector & terminal
(B55) No. 20 — Chassis ground:
5 CHECK HARNESS CONNECTOR
BETWEEN FWD SWITCH AND CHASSIS
GROUND.
Measure resistance of harness between FWD
switch and chassis ground.
Connector & terminal
(F67) No. 29 — Chassis ground:
6 CHECK INPUT SIGNAL FOR TCM.
1) Turn ignition switch to OFF.
2) Connect connector to TCM and FWD
switch.
3) Turn ignition switch to ON.
4) Measure signal voltage for TCM while
installing the fuse to FWD switch connector.
Connector & terminal
(B55) No. 20 (+) — Chassis ground (−):
7 CHECK INPUT SIGNAL FOR TCM.
Measure signal voltage for TCM while remov-
ing the fuse from FWD switch connector.
Connector & terminal
(B55) No. 20 (+) — Chassis ground (−):
Step
When fuse is inserted to
FWD switch, does LED
light up?
Is FWD indicator light bulb
OK?
Is the resistance less than
1 Ω?
Is the resistance more than
1 MΩ?
Is the resistance less than
1 Ω?
Is the voltage less than 1 V
in FWD switch while install-
ing?
Is the voltage more than 9
V in FWD switch while
removing?
AT-108
Check Yes
Go to step
CHECK BRAKE
SWITCH.<Ref. to
AT-109, CHECK
BRAKE SWITCH.,
Diagnostic Proce-
dure for No-diag-
nostic Trouble
Code (DTC).>
Go to step 3.
Go to step 4.
Go to step 5.
Go to step 6.
Go to step 7.
Go to step 8.
No
Go to step 2.
Replace FWD
indicator light
bulb. <Ref. to IDI-
15, Combination
Meter Assembly.>
Repair open cir-
cuit in harness
between TCM and
FWD switch con-
nector.
Repair short cir-
cuit in harness
between TCM and
FWD switch con-
nector.
Repair open cir-
cuit in harness
between FWD
switch connector
and chassis
ground.
Go to step 11.
Replace TCM.
<Ref. to AT-49,
Transmission
Control Module
(TCM).>