Page 477 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
Electronic control fuel injection pump
circuit*a, *b 1 1
111111111
Ð
*c, *d
Engine coolant temperature sensor
circuit*a, *b 1 1 1 1 EC-3481 *1
Vehicle speed sensor circuit *a, *b 1 EC-3485
1 - 5: The numbers refer to the order of inspection.
(continued on next page)
*a: Open
*b: Short
*c: Ground short
*d: Noise
*1: Compensation according to engine coolant temperature does not function.
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONYD25DDTi
Symptom Matrix Chart (Cont'd)
EC-3452
Page 478 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
Electronic control fuel injection pump
circuit*a, *b 1 1 1
111
Ð
*c, *d 1
Engine coolant temperature sensor
circuit*a, *b 1 1 1 1 1 EC-3481 *1
Vehicle speed sensor circuit *a, *b 1 EC-3485
1 - 5: The numbers refer to the order of inspection.
(continued on next page)
*a: Open
*b: Short
*c: Ground short
*d: Noise
*1: Compensation according to engine coolant temperature does not function.
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONYD25DDTi
Symptom Matrix Chart (Cont'd)
EC-3453
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 481 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
Start signal circuit *a, *b1111EC-3631 *3
PNP switch circuit*a, *b 1
EC-3634
*c
Accelerator position switch (Idle) cir-
cuit*a, *c 1 1 1 1 1
EC-3516
*b 1 1 1 *4
Accelerator position switch (Full) cir-
cuit*a, *b 1 1 1 EC-3516
Ignition switch circuit*a 1 111
EC-3471
*b*5
Power supply for ECM circuit*a 1 111
EC-3471
*b
1 - 5: The numbers refer to the order of inspection.
(continued on next page)
*a: Open
*b: Short
*c: Ground short
*d: Noise
*3: Start control does not function.
*4: Accelerator position sensor NG signal is output.
*5: Engine does not stop.
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONYD25DDTi
Symptom Matrix Chart (Cont'd)
EC-3456
Page 482 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
Start signal circuit *a, *b EC-3631 *3
PNP switch circuit*a, *b
1 1 EC-3634
*c
Accelerator position switch (Idle) cir-
cuit*a, *c
EC-3516
*b 1 1 *4
Accelerator position switch (Full) cir-
cuit*a, *b 1 1 EC-3516
Ignition switch circuit*a
EC-3471
*b*5
Power supply for ECM circuit*a
111
EC-3471
*b
1 - 5: The numbers refer to the order of inspection.
(continued on next page)
*a: Open
*b: Short
*c: Ground short
*d: Noise
*3: Start control does not function.
*4: Accelerator position sensor NG signal is output.
*5: Engine does not stop.
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONYD25DDTi
Symptom Matrix Chart (Cont'd)
EC-3457
Page 487 of 1306
Major Sensor Reference Graph in Data
Monitor Mode
The following are the major sensor reference graphs in ªDATA MONITORº mode.
ACCEL POS SEN, ªCKPSzRPM (TDC)º
Below is the data for ªACCEL POS SENº and ªCKPSzRPM (TDC)º when revving engine quickly up to 3,000
rpm under no load after warming up engine to the normal operating temperature.
Each value is for reference, the exact value may vary.
SEC947C
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONYD25DDTi
EC-3462
Page 490 of 1306

TER-
MINAL
NO.WIRE
COLORITEM CONDITIONDATA (DC Voltage and Pulse
Signal)
15 G/W Air conditioner relayEngine is running.
Air conditioner switch is ªOFFºBATTERY VOLTAGE
(11 - 14V)
Engine is running.
Both air conditioner switch and blower fan
switch are ªONº
(Compressor is operating)Approximately 0.1V
16 L/W Glow lampIgnition switch ªONº
Glow lamp is ªONºApproximately 1V
Ignition switch ªONº
Glow lamp is ªOFFºBATTERY VOLTAGE
(11 - 14V)
17 G/Y Stop lamp switchIgnition switch ªONº
Brake pedal fully releasedApproximately 0V
Ignition switch ªONº
Brake pedal depressedBATTERY VOLTAGE
(11 - 14V)
18 W/GMalfunction indicator
lampIgnition switch ªONº
Approximately 1V
Engine is running.
Idle speedBATTERY VOLTAGE
(11 - 14V)
19 L/OREngine coolant tempera-
ture sensorEngine is running.
Approximately 0 - 4.8V
Output voltage varies with
engine coolant temperature
20 R Start signalIgnition switch ªONº
Approximately 0V
Ignition switch ªSTARTº
BATTERY VOLTAGE
(11 - 14V)
21 Y Air conditioner switchEngine is running.
Air conditioner switch is ªOFFºBATTERY VOLTAGE
(11 - 14V)
Engine is running.
Both air conditioner switch and blower fan
switch are ªONº
(Compressor is operating)Approximately 0V
22 G/ORPark/Neutral position
switchIgnition switch ªONº
Gear position is ªNeutralºApproximately 0V
Ignition switch ªONº
Except the above gear positionBATTERY VOLTAGE
(11 - 14V)
23 WAccelerator position sen-
sorIgnition switch ªONº
Accelerator pedal fully released0.29 - 0.79V
Ignition switch ªONº
Accelerator pedal fully depressed3.48 - 4.64V
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONYD25DDTi
ECM Terminals and Reference Value
(Cont'd)
EC-3465