Page 472 of 1306
7 CHECK IDLE SPEED AGAIN
With CONSULT-II
1. Start engine and let it idle.
2. Select ªCKPSzRPM (TDC)º in ªDATA MONITORº mode with CONSULT-II.
3. Read idle speed.
SEF817Y
Without CONSULT-II
1. Start engine and let it idle.
2. Check idle speed.
750 25 rpm
OK or NG
OKcINSPECTION END
NGcGO TO 8.
8 CHECK AIR CLEANER FILTER
Check air cleaner filter for clogging or breaks.
OK or NG
OKcGO TO 9.
NGcReplace air cleaner filter.
9 CHECK FUEL INJECTION NOZZLE
Check fuel injection nozzle opening pressure. Refer to ªInjection pressure testº, EC-3418.
OK or NG
OKcGO TO 10.
NGcReplace fuel injection nozzle assembly.
TROUBLE DIAGNOSIS Ð BASIC INSPECTIONYD25DDTi
Basic Inspection (Cont'd)
EC-3447
Page 475 of 1306

Symptom Matrix Chart
SYSTEM Ð Basic engine control sys-
temSYMPTOM
Reference page
Feature of symptom, Check pointHARD/NO START/RESTART
(EXCP. HA)
ENGINE STALL
HESITATION/SURGING/FLAT SPOT
KNOCK/DETONATION
LACK OF POWER
POOR ACCELERATION
HI IDLE
LOW IDLE NO START (with first firing)
NO START (without first firing)
HARD TO START WHEN ENGINE IS COLD
HARD TO START WHEN ENGINE IS HOT
AT IDLE
DURING DRIVING
WHEN DECELERATINGWarranty symptom code AA AB AC AD AE AF
Electronic control fuel injection pump
mainframe4444444445544 Ð *1
Injection nozzle3333333334433EC-3415 *2
Glow system1111 1EC-3622
Engine body3333333 344 3 EMsection *3
EGR system3 3 EC-3606
Air cleaner and ducts 3 3 MA section *4
1 - 5: The numbers refer to the order of inspection.
(continued on next page)
*1: Fuel injection system malfunction or fuel injection timing control system malfunction may be the cause.
*2: Depends on open-valve pressure and spray pattern.
*3: Caused mainly by insufficient compression pressure.
*4: Symptom varies depending on off-position of air duct, etc.
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONYD25DDTi
EC-3450
Page 476 of 1306

SYSTEM Ð Basic engine control sys-
temSYMPTOM
Reference page
Feature of symptom, Check pointROUGH IDLE/HUNTING
IDLING VIBRATION
SLOW/NO RETURN TO IDLE
OVERHEAT/HIGH ENGINE COOLANT TEMPERATURE
EXCESSIVE FUEL CONSUMPTION
EXCESSIVE OIL CONSUMPTION
ABNORMAL SMOKE COLOR
DEAD BATTERY (UNDER CHARGE)
Malfunction indicator lamp illuminates.
Can be detected by CONSULT-II?
Fuel cutBLACK SMOKE
WHITE SMOKEWarranty symptom code AG AH AJ AK AL AM AP HA
Electronic control fuel injection pump
mainframe443 4 54 333 Ð *1
Injection nozzle 3 3 3 4 3 1 EC-3415 *2
Glow system 1 EC-3622
Engine body 3 3 3 3 3 3 EM section *3
EGR system 3 EC-3606
Air cleaner and ducts 3 3 MA section *4
1 - 5: The numbers refer to the order of inspection.
(continued on next page)
*1: Fuel injection system malfunction or fuel injection timing control system malfunction may be the cause.
*2: Depends on open-valve pressure and spray pattern.
*3: Caused mainly by insufficient compression pressure.
*4: Symptom varies depending on off-position of air duct, etc.
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONYD25DDTi
Symptom Matrix Chart (Cont'd)
EC-3451
Page 479 of 1306
SYSTEM Ð ENGINE CONTROL system
Malfunction
SYMPTOM
Reference page
Feature of symptom, Check pointHARD/NO START/RESTART
(EXCP. HA)
ENGINE STALL
HESITATION/SURGING/FLAT SPOT
KNOCK/DETONATION
LACK OF POWER
POOR ACCELERATION
HI IDLE
LOW IDLE NO START (with first firing)
NO START (without first firing)
HARD TO START WHEN ENGINE IS COLD
HARD TO START WHEN ENGINE IS HOT
AT IDLE
DURING DRIVING
WHEN DECELERATINGWarranty symptom code AA AB AC AD AE AF
ENGINE CONTROL
Fuel cut system line*a, *c
EC-3615
*b 1 1 1 1 *2
Accelerator position sensor circuit *a, *b 1 1 1 EC-3516
Crankshaft position sensor (TDC)
circuit*a,
*b, *d111111111EC-3535
Charge air pressure sensor circuit*a, *c
111
EC-3601
*b
1 - 5: The numbers refer to the order of inspection.
(continued on next page)
*a: Open
*b: Short
*c: Ground short
*d: Noise
*2: Engine runs on after turning ignition switch OFF.
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONYD25DDTi
Symptom Matrix Chart (Cont'd)
EC-3454
Page 480 of 1306
SYSTEM Ð ENGINE CONTROL system
Malfunction
SYMPTOM
Reference page
Feature of symptom, Check pointROUGH IDLE/HUNTING
IDLING VIBRATION
SLOW/NO RETURN TO IDLE
OVERHEAT/HIGH ENGINE COOLANT TEMPERATURE
EXCESSIVE FUEL CONSUMPTION
EXCESSIVE OIL CONSUMPTION
ABNORMAL SMOKE COLOR
DEAD BATTERY (UNDER CHARGE)
Malfunction indicator lamp illuminates.
Can be detected by CONSULT-II?
Fuel cutBLACK SMOKE
WHITE SMOKEWarranty symptom code AG AH AJ AK AL AM AP HA
ENGINE CONTROL
Fuel cut system line*a, *c 1 1
EC-3615
*b 1 *2
Accelerator position sensor circuit *a, *b 1 1 EC-3516
Crankshaft position sensor (TDC) cir-
cuit*a, *b,
*d1 1 1 1 EC-3535
Charge air pressure sensor circuit*a, *c
1 EC-3601
*b 1
1 - 5: The numbers refer to the order of inspection.
(continued on next page)
*a: Open
*b: Short
*c: Ground short
*d: Noise
*2: Engine runs on after turning ignition switch OFF.
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONYD25DDTi
Symptom Matrix Chart (Cont'd)
EC-3455
Page 485 of 1306

CONSULT-II Reference Value in Data Monitor
Mode
Remarks:
+Specification data are reference values.
+Specification data are output/input values which are detected or supplied by the ECM at the connector.
* Specification data may not be directly related to their components signals/values/operations.
MONITOR ITEM CONDITION SPECIFICATION
CKPSzRPM (TDC)
+Tachometer: Connect
+Run engine and compare tachometer indication with the CONSULT-II value.Almost the same speed as the
CONSULT-II value.
CMPSzRPM-PUMP
COOLAN TEMP/S+Engine: After warming up More than 80ÉC (176ÉF)
VHCL SPEED SE+Turn drive wheels and compare speedometer indication with the CONSULT-II valueAlmost the same speed as the
CONSULT-II value
FUEL TEMP SEN+Engine: After warming up More than 40ÉC (104ÉF)
ACCEL POS SEN+Ignition switch: ON
(Engine stopped)Accelerator pedal: fully released 0.29 - 0.79V
Accelerator pedal: fully depressed Approx. 3.48 - 4.64V
FULL ACCEL SW+Ignition switch: ON
(Engine stopped)Accelerator pedal: fully depressed ON
Except above OFF
OFF ACCEL SW+Ignition switch: ON
(Engine stopped)Accelerator pedal: fully released ON
Accelerator pedal: slightly open OFF
SPILL/V+Engine: After warming up Idle speed Approx. 13ÉCA
BATTERY VOLT+Ignition switch: ON (Engine stopped) 11 - 14V
I/C INT/A T/S+Ignition switch: ONIntake air temperature
Approx. 0ÉC: Approx. 4.2V
Approx. 20ÉC: Approx. 3.5V
P/N POSI SW+Ignition switch: ONShift lever: Park/Neutral ON
Except above OFF
START SIGNAL+Ignition switch: ON®START®ON OFF®ON®OFF
AIR COND SIG+Engine: After warming up, idle the
engineAir conditioner switch: OFF OFF
Air conditioner switch: ON
(Compressor operates.)ON
BRAKE SW+Ignition switch: ONBrake pedal: depressed ON
Brake pedal: released OFF
BRAKE SW2+Ignition switch: ONBrake pedal: depressed ON
Brake pedal: released OFF
IGN SW+Ignition switch: ON®OFF ON®OFF
WARM UP SW+Ignition switch: ONHeat up switch: ON ON
Heat up switch: OFF OFF
TURBO BST SEN+Engine: After warming up
+Shift lever: Neutral positionIdle speed Approx. Atmospheric pressure
Engine speed is 2,000 rpm Apporx. 106.0 kPa
DECELER F/CUT+Engine: After warming up Idle speed OFF
INJ TIMG C/V+Engine: After warming up, idle the engine. Approx. 50 - 70%
AIR COND RLY+Engine: After warming up, idle the
engineAir conditioner switch: OFF OFF
Air conditioner switch: ON
(Compressor operates.)ON
GLOW RLY+Refer to EC-3622.
COOLING FAN+When cooling fan is stopped. OFF
+When cooling fan operates. ON
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONYD25DDTi
EC-3460
Page 492 of 1306

TER-
MINAL
NO.WIRE
COLORITEM CONDITIONDATA (DC Voltage and Pulse
Signal)
42 G/R
Data link connectorEngine is running.
Idle speed (CONSULT-II is connected and
turned on)Approximately 0V
64 G/BApproximately 0.2V
65 GY/LLess than 9V
44 YCrankshaft position sen-
sor (TDC)Engine is running.
Warm-up condition
Idle speedApproximately 0.04V
SEF333Y
Engine is running.
Warm-up condition
Engine speed is 2,000 rpmApproximately 0.04V
SEF334Y
46 P/LCharge air pressure sen-
sorEngine is running.Warm-up condition
Idle speedApproximately 2.7V
47 BRCrankshaft position sen-
sor (TDC) groundEngine is running.
Warm-up condition
Idle speedApproximately 0V
48 OR/LAccelerator position sen-
sor power supplyIgnition switch ªONº
Approximately 5V
49 W Sensor's power supplyIgnition switch ªONº
Approximately 5V
50 B Sensors' groundEngine is running.
Warm-up condition
Idle speedApproximately 0V
51 B/WAccelerator position sen-
sor groundEngine is running.
Warm-up condition
Idle speedApproximately 0V
52 L/WElectronic control fuel
injection pumpEngine is running.
Idle speedApproximately 0.1V
53 L/RElectronic control fuel
injection pumpEngine is running.
Idle speedApproximately 0.45V
Engine is running.
Engine speed is 2,000 rpmApproximately 0.7V
56
61R
RPower supply for ECM Ignition switch ªONº
BATTERY VOLTAGE
(11 - 14V)
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONYD25DDTi
ECM Terminals and Reference Value
(Cont'd)
EC-3467
Page 533 of 1306

Description
SYSTEM DESCRIPTION
The ECM and the electronic control fuel injection pump control
unit (abbreviated as the injection pump control unit) perform the
real time communication (signal exchange).
The ECM transmits the signals of the target fuel injection
amount, target fuel injection timing, and engine speed, etc., and
receives the signals of the pump speed and fuel temperature,
etc. from the injection pump control unit.
By those signals, the injection pump controls the optimum fuel
injection amount and injection timing of the spill valve and tim-
ing control valve.
Injection pump control unit has an on board diagnostic system,
which detects malfunctions related to sensors or actuators built-
into electronic control fuel injection pump. These malfunction
information are transferred through the line (circuit) from injection
pump control unit to ECM.
FUEL INJECTION AMOUNT CONTROL
In accordance with the target fuel injection amount signal from
the ECM, the injection amount is controlled by controlling the spill
valve in the injection pump and by changing the needle opening
time.
FUEL INJECTION TIMING CONTROL
Based on the target fuel injection timing signal from the ECM, the
injection timing is controlled in accordance with the timer spring
by performing the duty control of the timing control valve in the
injection pump and by adjusting the pressure of the timer piston
high pressure chamber.
FUEL TEMPERATURE SENSOR
The sensor detects the fuel temperature in the injection pump
and calibrates the injection amount change by the fuel tempera-
ture.
CAM RING POSITION SENSOR
The sensor detects the passing of the protrusion on the sensor
wheel in the injection pump by the semiconductor magnetic
resistance element sensor. The cam ring position sensor syn-
chronizes with the cam ring, and detects the actual advance
amount. The injection pump control unit measures the injection
pump revolution by the signal of the cam ring position sensor.
SEF437Y
DTC 0402 P9zFUEL TEMP SENYD25DDTi
EC-3508