
DESCRIPTION FOR WORK FLOW
STEP DESCRIPTION
STEP IGet detailed information about the conditions and the environment when the incident/symptom occurred using
the ªDIAGNOSTIC WORKSHEETº, EC-46.
STEP IIBefore confirming the concern, check and write down (print out using CONSULT-II) the DTC, then erase the
DTC. Refer to EC-33.
If the incident cannot be verified, perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-78.
Study the relationship between the cause, specified by DTC, and the symptom described by the customer. (The
ªSymptom Matrix Chartº will be useful. Refer to EC-56.) Also check related service bulletins for information.
STEP IIITry to confirm the symptom and under what conditions the incident occurs.
The ªDIAGNOSTIC WORK SHEETº is useful to verify the incident. Connect CONSULT-II to the vehicle in DATA
MONITOR (AUTO TRIG) mode and check real time diagnosis results.
If the incident cannot be verified, perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-78.
If the malfunction code is detected, skip STEP IV and perform STEP V.
STEP IVTry to detect the DTC by driving in (or performing) the ªDTC Confirmation Procedureº. Check and read the DTC
by using CONSULT-II.
During the DTC verification, be sure to connect CONSULT-II to the vehicle in DATA MONITOR (AUTO TRIG)
mode and check real time diagnosis results.
If the incident cannot be verified, perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-78.
In case the ªDTC Confirmation Procedureº is not available, perform the ªOverall Function Checkº instead. The
DTC cannot be displayed by this check, however, this simplified ªcheckº is an effective alternative.
The ªNGº result of the ªOverall Function Checkº is the same as the DTC detection.
STEP VTake the appropriate action based on the results of STEP I through IV.
If the malfunction code is indicated, proceed to TROUBLE DIAGNOSIS FOR DTC XXXX.
If the normal code is indicated, proceed to the Basic Inspection, EC-50. Then perform inspections according to
the Symptom Matrix Chart. Refer to EC-56.
STEP VIIdentify where to begin diagnosis based on the relationship study between symptom and possible causes.
Inspect the system for mechanical binding, loose connectors or wiring damage using (tracing) ªHarness Layoutsº.
Gently shake the related connectors, components or wiring harness with CONSULT-II set in ªDATA MONITOR
(AUTO TRIG)º mode.
Check the voltage of the related ECM terminals or monitor the output data from the related sensors with CON-
SULT-II. Refer to EC-69 or EC-66.
The ªDiagnostic Procedureº in EC section contains a description based on open circuit inspection. A short circuit
inspection is also required for the circuit check in the Diagnostic Procedure. For details, refer to GI section (ªCir-
cuit Inspectionº, ªHOW TO PERFORM EFFICIENT DIAGNOSIS FOR AN ELECTRICAL INCIDENTº).
Repair or replace the malfunction parts.
If the malfunctioning part cannot be detected, perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT
INCIDENTº, EC-78.
STEP VIIOnce you have repaired the circuit or replaced a component, you need to run the engine in the same conditions
and circumstances which resulted in the customer's initial complaint.
Perform the ªDTC Confirmation Procedureº and confirm the normal code (DTC No. 0505) is detected. If the inci-
dent is still detected in the final check, perform STEP VI by using a different method from the previous one.
Before returning the vehicle to the customer, be sure to erase the unnecessary (already fixed) DTC in ECM.
(Refer to EC-33.)
TROUBLE DIAGNOSIS Ð INTRODUCTIONZD30DDTi
Work Flow (Cont'd)
EC-49

Basic Inspection
Precaution:
Perform Basic Inspection without electrical or mechanical
loads applied;
IShift lever is in neutral position,
IHeat up switch is OFF,
IHeadlamp switch is OFF,
IAir conditioner switch is OFF,
IRear defogger switch is OFF,
ISteering wheel is in the straight-ahead position, etc.
1 INSPECTION START
1. Check service records for any recent repairs that may indicate a related problem.
2. Check the current need for scheduled maintenance, especially for fuel filter and air cleaner filter. Refer to MA section.
3. Open engine hood and check the following:
IHarness connectors for improper connections
IVacuum hoses for splits, kinks, or improper connections
IWiring for improper connections, pinches, or cuts
SEF142I
4. Start engine and warm it up to the normal operating temperature.
EGO TO 2.
2 PREPARATION FOR CHECKING IDLE SPEED
With CONSULT-II
Connect CONSULT-II to the data link connector.
Without CONSULT-II
Install diesel tacho tester to the vehicle.
EGO TO 3.
TROUBLE DIAGNOSIS Ð BASIC INSPECTIONZD30DDTi
EC-50

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
EGR volume control valve circuit*a, *b
EC-222
*c*8
Glow relay circuit*a 1111
EC-239*9
*b*10
ECM relay (Self-shutoff) circuit*a 111
EC-79
*b*11
ECM, Connector circuit *a, *b2222222222222EC-121,
200, 213
Air conditioner relay circuit*a
EC-289*12
*b*13
Air conditioner switch circuit*a, *c
EC-289*13
*b*14
1 - 5: The numbers refer to the order of inspection.
(continued on next page)
*a: Open
*b: Short
*c: Ground short
*d: Noise
*8: Does not stop operating.
*9: Glow lamp does not turn on.
*10: Glow lamp does not turn off. *11: Ground short makes engine unable to stop.
*12: Air conditioner does not operate.
*13: Air conditioner does not stop operating.
*14: Air conditioner does not work.
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONZD30DDTi
Symptom Matrix Chart (Cont'd)
EC-64

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
EGR volume control valve circuit*a, *b
EC-222
*c 1 *8
Glow relay circuit*a 1
EC-239*9
*b*10
ECM relay (Self-shutoff) circuit*a 1
EC-79
*b 1 1 *11
ECM, Connector circuit *a, *b222222222222EC-121,
200, 213
Air conditioner relay circuit*a
EC-289*12
*b*13
Air conditioner switch circuit*a, *c
EC-289*13
*b*14
1 - 5: The numbers refer to the order of inspection.
*a: Open
*b: Short
*c: Ground short
*d: Noise
*8: Does not stop operating.
*9: Glow lamp does not turn on.
*10: Glow lamp does not turn off.
*11: Ground short makes engine unable to stop.
*12: Air conditioner does not operate.
*13: Air conditioner does not stop operating.
*14: Air conditioner does not work.
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONZD30DDTi
Symptom Matrix Chart (Cont'd)
EC-65

CONSULT-II Reference Value in Data Monitor
Mode
Remarks:
ISpecification data are reference values.
ISpecification 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
CKPS×RPM (TDC)
ITachometer: Connect
IRun engine and compare tachometer indication with the CONSULT-II value.Almost the same speed as the
CONSULT-II value.
CMPS×RPM-PUMP
COOLAN TEMP/SIEngine: After warming up More than 70ÉC (158ÉF)
VHCL SPEED SEITurn drive wheels and compare speedometer indication with the CONSULT-II valueAlmost the same speed as the
CONSULT-II value
FUEL TEMP SENIEngine: After warming up More than 40ÉC (104ÉF)
ACCEL POS SENIIgnition switch: ON
(Engine stopped)Accelerator pedal: fully released 0.40 - 0.60V
Accelerator pedal: fully depressed Approx. 4.5V
FULL ACCEL SWIIgnition switch: ON
(Engine stopped)Accelerator pedal: fully depressed ON
Except above OFF
ACCEL SW (FC)IIgnition switch: ON
(Engine stopped)Accelerator pedal: fully released CLOSE
Accelerator pedal: slightly open OPEN
OFF ACCEL SWIIgnition switch: ON
(Engine stopped)Accelerator pedal: fully released ON
Accelerator pedal: slightly open OFF
SPILL/VIEngine: After warming up Approx. 13ÉCA
BATTERY VOLTIIgnition switch: ON (Engine stopped) 11 - 14V
P/N POSI SWIIgnition switch: ONShift lever: Park/Neutral ON
Except above OFF
START SIGNALIIgnition switch: ON,START,ON OFF,ON,OFF
AIR COND SIGIEngine: After warming up, idle the
engineAir conditioner switch: OFF OFF
Air conditioner switch: ON
(Compressor operates.)ON
BRAKE SWIIgnition switch: ONBrake pedal: depressed ON
Brake pedal: released OFF
IGN SWIIgnition switch: ON,OFF ON,OFF
WARM UP SWIIgnition switch: ONHeat up switch: ON ON
Heat up switch: OFF OFF
MAS AIR/FL SEIEngine: After warming up
IAir conditioner switch: OFF
IShift lever: Neutral position
INo-loadIdle 1.6 - 2.0V
DECELER F/CUTIEngine: After warming up Idle OFF
INJ TIMG C/VIEngine: After warming up, idle the engine. Approx. 50 - 70%
AIR COND RLYIEngine: After warming up, idle the
engineAir conditioner switch: OFF OFF
Air conditioner switch: ON
(Compressor operates.)ON
GLOW RLYIRefer to EC-239.
COOLING FANIWhen cooling fan is stopped. OFF
IWhen cooling fan operates. ON
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONZD30DDTi
EC-66

MONITOR ITEM CONDITION SPECIFICATION
EGR VOL CON/VIEngine: After warming up
IAir conditioner switch: ªOFFº
IShift lever: Neutral position
INo-loadAfter 1 minute of idling More than 10 steps
Revving engine from idle to 3,200 rpm 0 step
VNT S/V 1IEngine: After warming up
IAir conditioner switch: ªOFFº
IShift lever: Neutral position
INo-loadIdle Approx. 56%
2,000 rpm Approx. 20%
BARO SENIIgnition switch: ONAltitude
Approx.0m(0ft): Approx. 100.62
kPa (1.0062 bar, 1.026 kg/cm
2,
14.59 psi)
Approx. 1,000 m (3,281 ft): Approx.
88.95 kPa (0.8895 bar, 0.907
kg/cm
2, 12.90 psi)
Approx. 1,500 m (4,922 ft): Approx.
83.16 kPa (0.8316 bar, 0.848
kg/cm
2, 12.06 psi)
Approx. 2,000 m (6,562 ft): Approx.
78.36 kPa (0.7836 bar, 0.799
kg/cm
2, 11.36 psi)
SWRL CON S/V 1ILift up the vehicle
IEngine: After warming up let it idle for
more than 1 second.
IAir conditioner switch: ªOFFº
INo-loadShift lever: Except ªPº and ªNeutralº posi-
tionsON
Shift lever: Neutral position OFF
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONZD30DDTi
CONSULT-II Reference Value in Data Monitor
Mode (Cont'd)
EC-67

ECM HARNESS CONNECTOR TERMINAL LAYOUT
ECM INSPECTION TABLE
Remarks: Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may damage the
ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TER-
MINAL
NO.WIRE
COLORITEM CONDITIONDATA (DC Voltage and Pulse
Signal)
2 L/GIntake air control valve
control solenoid valveEngine is running.
BATTERY VOLTAGE
(11 - 14V)
Ignition switch ªOFFº
For a few seconds after turning ignition
switch ªOFFºApproximately 0.1V
4 G ECM relay (Self-shutoff)Ignition switch ªONº
Ignition switch ªOFFº
For a few seconds after turning ignition
switch ªOFFºApproximately 0.25V
Ignition switch ªOFFº
A few seconds passed after turning ignition
switch ªOFFºBATTERY VOLTAGE
(11 - 14V)
SEF064P
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONZD30DDTi
ECM Terminals and Reference Value (Cont'd)
EC-70

TER-
MINAL
NO.WIRE
COLORITEM CONDITIONDATA (DC Voltage and Pulse
Signal)
5 L/B TachometerEngine is running.
Warm-up condition
Idle speedApproximately 5.7V
SEF255Z
Engine is running.
Warm-up condition
Engine speed is 2,000 rpmApproximately 6V
SEF256Z
14 LG/R Cooling fan relayEngine is running.Cooling fan is not operatingBATTERY VOLTAGE
(11 - 14V)
Engine is running.
Cooling fan is operatingApproximately 0.1V
15 G/PU 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 G/W Glow lampIgnition switch ªONº
Glow lamp is ªONºApproximately 1V
Ignition switch ªONº
Glow lamp is ªOFFºBATTERY VOLTAGE
(11 - 14V)
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONZD30DDTi
ECM Terminals and Reference Value (Cont'd)
EC-71