Page 428 of 1306
tion due to receiving external noise, degraded operation
of ICs, etc.
+Keep engine control system parts and harnesses dry.
+Before replacing ECM, perform Terminals and Reference
Value inspection and make sure ECM functions properly.
Refer to EC-3464.
+Fuel filter switch is equipped except for Europe.
If MIL illuminates or blinks irregularly when engine is
running, water may have accumulated in fuel filter. Drain
water from fuel filter. Refer to EC-3427. If this does not
correct the problem, perform specified trouble diagnos-
tic procedures.
+After performing each TROUBLE DIAGNOSIS, perform
ªDTC Confirmation Procedureº or ªOverall Function
Checkº.
The DTC should not be displayed in the ª DTC Confirma-
tion Procedureº if the repair is completed. The ªOverall
Function Checkº should be a good result if the repair is
completed.
MEF040D
SAT652J
PRECAUTIONSYD25DDTi
Precautions (Cont'd)
EC-3403
Page 429 of 1306

+When measuring ECM signals with a circuit tester, never
allow the two tester probes to contact.
Accidental contact of probes will cause a short circuit
and damage the ECM power transistor.
+Do not use ECM ground terminals when measuring
input/output voltage. Doing so may result in damage to
the ECM's transistor. Use a ground other than ECM
terminals, such as the ground.
+Do not disconnect pump harness connector with engine
running.
+Do not disassemble electronic fuel injection pump.
If NG, take proper action.
+Do not disassemble injection nozzle.
If NG, replace injection nozzle.
+Do not shock or jar the crankshaft position sensor
(TDC).
+Do not depress accelerator pedal when starting.
+Immediately after starting, do not rev up engine unnec-
essarily.
+Do not rev up engine just prior to shutdown.
+When installing C.B. ham radio or a mobile phone, be
sure to observe the following as it may adversely affect
electronic control systems depending on its installation
location.
1) Keep the antenna as far as possible away from the ECM.
2) Keep the antenna feeder line more than 20 cm (7.9 in)
away from the harness of electronic controls.
Do not let them run parallel for a long distance.
3) Adjust the antenna and feeder line so that the standing-
wave ratio can be kept smaller.
4) Be sure to ground the radio to vehicle body.
SEF348N
SEF437Y
SEF709Y
SEF708Y
PRECAUTIONSYD25DDTi
Precautions (Cont'd)
EC-3404
Page 430 of 1306
Engine Control Component Parts Location
SEC225D
ENGINE AND EMISSION CONTROL OVERALL SYSTEMYD25DDTi
EC-3405
Page 431 of 1306
SEC226D
ENGINE AND EMISSION CONTROL OVERALL SYSTEMYD25DDTi
Engine Control Component Parts Location
(Cont'd)
EC-3406
Page 432 of 1306
SEC227D
ENGINE AND EMISSION CONTROL OVERALL SYSTEMYD25DDTi
Engine Control Component Parts Location
(Cont'd)
EC-3407
Page 433 of 1306
Circuit Diagram
GEC273A
ENGINE AND EMISSION CONTROL OVERALL SYSTEMYD25DDTi
EC-3408
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System Diagram
SEC239D
ENGINE AND EMISSION CONTROL OVERALL SYSTEMYD25DDTi
EC-3409
Page 435 of 1306
System Chart
Input (Sensor) ECM Function Output (Actuator)
+Electronic control fuel injection pump
+Crankshaft position sensor (TDC)
+Engine coolant temperature sensor
+Accelerator position sensor
+Accelerator position switch
+Park/Neutral position (PNP) switch
+Ignition switch
+Battery voltage
+Vehicle speed sensor
+Air conditioner switch
+Stop lamp switch
+Charge air pressure sensor
+Intake air temperature sensorFuel injection control Electronic control fuel injection pump
Fuel injection timing control Electronic control fuel injection pump
Fuel cut control Electronic control fuel injection pump
Glow control system Glow relay & glow lamp
On board diagnostic system MIL (On the instrument panel)
EGR volume control EGR volume control valve
Cooling fan control Cooling fan relay
Air conditioning cut control Air conditioner relay
ENGINE AND EMISSION CONTROL OVERALL SYSTEMYD25DDTi
EC-3410