General Description - Subaru LEGACY Service Manual

3. General Description

A: CAUTION
1) Airbag system wiring harness is routed near the
ECM, main relay and fuel pump relay.
CAUTION:
• All airbag system wiring harnesses and con-
nectors are colored yellow. Do not use electri-
cal test equipment on these circuits.
• Be careful not to damage the airbag system
wiring harness when servicing the ECM, TCM,
main relay and fuel pump relay.
2) Never connect the battery in reverse polarity.
• The ECM will be destroyed instantly.
• The fuel injector and other parts will be dam-
aged.
3) Do not disconnect the battery terminals while the
engine is running.
A large counter electromotive force will be generat-
ed in the generator, and this voltage may damage
electronic parts such as ECM, etc.
4) Before disconnecting the connectors of each
sensor and ECM, be sure to turn the ignition switch
to OFF. Perform the inspection mode after con-
necting the connectors.
5) Poor contact has been identified as a primary
cause of this problem. Measure the voltage or re-
sistance of individual sensor or all electrical control
modules using a tapered pin with a diameter of less
than 0.64 mm (0.025 in). Do not insert the pin more
than 5 mm (0.20 in) into the part.
6) Remove the ECM from the located position after
disconnecting two cables on battery.
Otherwise, the ECM may be damaged.
CAUTION:
When replacing the ECM, be careful not to use
the wrong spec. ECM to avoid any damage on
the fuel injection system.
NOTE:
Immobilizer system must be registered when in-
stalling the ECM of the model with immobilizer. For
doing so, all ignition keys and ID cards should be
prepared. Refer to "REGISTRATION MANUAL
FOR IMMOBILIZER".
7) Connectors of each sensor in the engine com-
partment and the harness connectors on the en-
gine side and body side are all designed to be
waterproof. However, it is still necessary to take
care not to allow water to get into the connectors
when washing the vehicle, or when servicing the
vehicle on a rainy day.
General Description
8) Use ECM mounting stud bolts as the grounding
point to chassis when measuring voltage and resis-
tance inside the passenger compartment.
9) Use engine grounding terminal or engine as the
grounding point to the chassis when measuring
voltage and resistance in the engine compartment.
10) Use TCM mounting stud bolts as the grounding
point to chassis when measuring voltage and resis-
tance inside the passenger compartment.
11) Every MFI-related part is a precision part. Do
not drop them.
12) Observe the following cautions when installing
a radio in MFI equipped models.
CAUTION:
• The antenna must be kept as far apart as pos-
sible from the control unit. (The ECM is located
under the steering column, inside of instrument
panel lower trim panel.)
EN(H4SO 2.5)(diag)-5
ENGINE (DIAGNOSTICS)
(A)
(A) Stud bolt
(A)
(A) Stud bolt
EN-00001
FU-01090
EN-00154