EN(H4DOTC 2.5)-5
ENGINE (DIAGNOSTIC)
General Description
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 harness and con-
nectors are all colored yellow. Do not use the
electrical 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 immediately.
The fuel injector and other part will be damaged.
3) Do not disconnect the battery terminals while the
engine is running.
A large counter electromotive force will be gener-
ated in the generator, and this voltage may damage
electronic parts such as ECM, etc.
4) Before disconnecting the connectors of each
sensor and the ECM, be sure to turn OFF the igni-
tion switch.
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 damaging the
fuel injection system.
7) Connectors to 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, take care not to allow water
to get into the connectors when washing the vehi-
cle, or when servicing the vehicle on a rainy day. 8) Use ECM mounting stud bolts on the body head
grounding point when measuring voltage and resis-
tance inside the passenger compartment.
9) Use engine ground terminal or engine proper as
the grounding point to the body when measuring
voltage and resistance in the engine compartment.
10) Every MFI-related part is a precision part. Do
not drop them.
11) 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 the instrument panel lower trim panel.)
The antenna feeder must be placed as far
apart as possible from the ECM and MFI har-
ness.
Carefully adjust the antenna for correct match-
ing.
When mounting a large power type radio, pay
special attention to the three items above men-
tioned.
Incorrect installation of the radio may affect
the operation of the ECM.
12) Before disconnecting the fuel hose, disconnect
the fuel pump connector and crank the engine for
more than five seconds to release pressure in the
fuel system. If engine starts during this operation,
run it until it stops.
(A) Stud bolt
EN-00069
(A)
EN-01201
