
Symptom Matrix Chart
SYSTEM
Ð Basic engine
control systemSYMPTOM
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
ROUGH 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?
Fuel cutNO START (with ®rst ®ring)
NO START (without ®rst ®ring)
HARD TO START WHEN ENGINE IS COLD
HARD TO START WHEN ENGINE IS HOT
AT IDLE
DURING DRIVING
WHEN DECELERATING
BLACK SMOKE
WHITE SMOKEWarranty symptom
codeAA AB AC AD AE AF AG AH AJ AK AL AM AP HA
Injection
timingAdvancedjj
++j+jj+jEC-47
Retardedjj
++j+jj+jEC-47
Electric injection pump
mainframe
++++jjjjj+jjj++jj+j jjjÐ*1
Injection nozzlejjjjjjj
+jj j++ +EC-22 *2
Glow systemjj
++ + +EC-151
Engine body
jj
++jjj+jj j++jjj+EM sec-
tion*3
EGR system
++ +EC-156
Air cleaner and ducts
++ +jMA sec-
tion*4
+; High Possibility Item
j; Low Possibility Item
*1: Insufficient or excess amount. Governor 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 Description
EC-48

SYSTEM
Ð ECCS systemMalfunction
SYMPTOM
Reference
page Feature of symptom
Check point
HARD/NO START/
RESTART (EXCP. HA) ENGINE STALL HESITATION/SURGING/FLAT SPOT KNOCK/DETONATION
LACK OF POWER
POOR ACCELERATION
HI IDLE
LOW IDLE
ROUGH 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?
Fuel cut
NO START (with ®rst ®ring) NO START (without ®rst ®ring)
HARD TO START WHEN ENGINE IS COLD
HARD TO START WHEN ENGINE IS HOT
AT IDLE
DURING DRIVING
WHEN DECELERATINGBLACK SMOKE WHITE SMOKE
Warranty symptom code AA AB AC AD AE AF AG AH AJ AK AL AM AP HAECCS
Camshaft position sensor (PUMP) cir-
cuitopen, shortjj
EC-69Tachometer malfunction
noisejjjj jj
Mass air ¯ow sensor circuitopen, ground shortjjj j
EC-74
shortjjj
Engine coolant temperature sensor
circuitopen, shortjjj jjj jjEC-79Compensation according to
engine coolant temperature does
not function.
Vehicle speed sensor circuit open, shortjjEC-83
Control sleeve position sensor circuit open, shortjjjjjjEC-87
Adjustment resistor circuit open, shortj j jjjj j jEC-92
Electric governor circuitopen, ground shortj jjjjjj
EC-96
shortjj
Injection timing control valve circuitopen, shortjjj
EC-101Injection timing cannot be con-
trolled.
ground shortjj
Accelerator switch (FC) circuitopen, shortjjj
EC-106
ground shortjj
Charge air temperature sensor circuit open, shortjEC-122
Needle lift sensor circuit open, shortjjjEC-126
Fuel cut solenoid valve circuitopen, ground shortj jjjj
EC-130
shortjjjEngine runs on after turning igni-
tion switch OFF.
Fuel temperature sensor circuit open, shortjj jj jj j jj jEC-135Compensation for amount of fuel
injected according to fuel tem-
perature does not function.
Accelerator position sensor circuit open, shortjjj jjEC-139
Crankshaft position sensor (TDC) cir-
cuitopen, shortjj jj
EC-144
noisejjjjj
TROUBLE DIAGNOSIS Ð General Description
Symptom Matrix Chart (Cont'd)
EC-49

SYSTEM
Ð ECCS systemMalfunction
SYMPTOM
Reference page Feature of symptom
Check point
HARD/NO START/
RESTART (EXCP. HA) ENGINE STALL HESITATION/SURGING/FLAT SPOT KNOCK/DETONATION
LACK OF POWER
POOR ACCELERATION
HI IDLE
LOW IDLE
ROUGH 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?
Fuel cut
NO START (with ®rst ®ring) NO START (without ®rst ®ring)
HARD TO START WHEN ENGINE IS COLD
HARD TO START WHEN ENGINE IS HOT
AT IDLE
DURING DRIVING
WHEN DECELERATINGBLACK SMOKE WHITE SMOKE
Warranty symptom code AA AB AC AD AE AF AG AH AJ AK AL AM AP HAECCS
Start signal circuit open, shortjjEC-163 Start control does not function.
Neutral position switch circuitopen, shortjjj
EC-170
ground shortjj
Accelerator position switch (Idle) cir-
cuitopen, ground shortjj j
EC-165
shortjjj jjAccelerator position sensor NG
signal is output.
Accelerator position switch (Full) cir-
cuitopen, shortjjj jjEC-165
Ignition switch circuitopenj jjj
EC-63
shortEngine does not stop.
Power supply for ECM circuitopenjjj
EC-63
shortjj
Throttle control solenoid valve circuitopen, short
EC-156Does not operate.
ground shortjj jDoes not stop operating.
EGRC-solenoid valve A, B circuitopen, short
EC-156
ground shortjDoes not stop operating.
Glow relay circuitopenjjjjj
EC-151Glow lamp does not turn on.
shortGlow lamp does not turn off.
ECCS relay (Self-shutoff) circuitopenjjjj
EC-63
shortjjGround short makes engine
unable to stop.
ECM, Connector circuit open, shortjjjjjjjjjjjjj jjjjjjjjjjjjEC-111
Air conditioner relay circuitopen
EC-187Air conditioner does not operate.
shortAir conditioner does not stop
operating.
Air conditioner switch circuitopen, ground short
EC-187Air conditioner does not stop
operating.
shortAir conditioner does not work.
TROUBLE DIAGNOSIS Ð General Description
Symptom Matrix Chart (Cont'd)
EC-50

TER-
MINAL
NO.WIRE
COLORITEM CONDITIONDATA
(DC Voltage and Pulse
Signal)
102
108G/Y Electric governor groundEngine is running.
Idle speedApproximately 10V
SEF727V
Engine is running.
Engine speed is 2,000 rpm.Approximately 10V
SEF728V
11 6
11 7W Power supply for ECM Ignition switch ``ON''BATTERY VOLTAGE
(11 - 14V)
ON BOARD DIAGNOSIS LOGIC
Diagnostic
Trouble Code
No.Malfunction is detected when ....Check Items
(Possible cause)
18, 22, 25+Fuel injection feedback system does not operate prop-
erly. (This system consists essentially of ECM, electric
governor and control sleeve position sensor.)+Main power supply circuit (ECM terminals
11 6,11 7)
and fuse
+Harness or connectors
(Electric governor and control sleeve position sensor
circuit)
+Electric governor
+Electronic fuel injection pump
+ECM
TROUBLE DIAGNOSIS FOR ``F/INJ F/B 2'' (DTC 18),
``F/INJ F/B'' (DTC 22), ``ELECTRIC GOV'' (DTC 25)
Electric Governor (Cont'd)
EC-97

ON BOARD DIAGNOSIS LOGIC
Diagnostic
Trouble Code
No.Malfunction is detected when ....Check Items
(Possible cause)
21+Injection timing feedback system does not operate
properly. (This system consists essentially of ECM,
injection timing control valve and needle lift sensor.)+Harness or connectors
[Injection timing control valve, needle lift sensor,
crankshaft position sensor (TDC) circuits]
+Injection timing control valve
+Needle lift sensor
+Crankshaft position sensor (TDC)
+Air in fuel line
DIAGNOSTIC TROUBLE CODE CONFIRMATION
PROCEDURE
Note: If both DTC 21 and 34 or 47 are displayed, perform
TROUBLE DIAGNOSIS FOR DTC 34 or 47. (See EC-126
or EC-144.)
1) Turn ignition switch ``ON'' and select ``DATA MONITOR''
mode with CONSULT.
2) Start engine and warm it up to normal operating tem-
perature.
3) Run engine for 2 seconds at 3,000 rpm. Return engine
speed to idle, then increase to 3,000 rpm under no load.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------OR-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1) Start engine and warm it up to normal operating tem-
perature.
2) Run engine for 2 seconds at 3,000 rpm. Return engine
speed to idle, then increase to 3,000 rpm under no load.
3) Turn ignition switch ``OFF'', wait at least 5 seconds and
then turn ``ON''.
4) Perform ``Diagnostic Test Mode II (Self-diagnostic
results)'' with ECM.
Note: If a malfunction occurs intermittently, conduct suitable
driving pattern for 10 minutes. This makes it possible to
determine DTC.
SEF751V
TROUBLE DIAGNOSIS FOR ``F/INJ TIMG F/B'' (DTC 21)
Injection Timing Control Valve (Cont'd)
EC-102

Cooling Fan (Overheat)
SYSTEM DESCRIPTION
Vehicle speed sensorcVehicle speed
ECM
(ECCS-D
control
mod-
ule)
cCooling fan
relayEngine coolant temperature sensorcEngine coolant temperature
Air conditioner switch
cAir conditioner ``ON'' signal
The ECM controls the cooling fan corresponding to the vehicle speed, engine coolant temperature, air condi-
tioner system pressure and air conditioner ON signal. The control system has 2-step control [ON/OFF].
Operation
CONSULT REFERENCE VALUE IN DATA MONITOR MODE
Remarks: Speci®cation data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
AIR COND SIG+Engine: After warming up, idle
the engineAir conditioner switch: OFF OFF
Air conditioner switch: ON
(Compressor operates.)ON
COOLING FAN+When cooling fan is stopped. OFF
+When cooling fan operates. ON
ECM TERMINALS AND REFERENCE VALUE
Remarks: Speci®cation data are reference values and are measured between each terminal andV43(ECCS
ground) with a voltmeter.
TER-
MINAL
NO.WIRE
COLORITEM CONDITIONDATA
(DC Voltage and Pulse
Signal)
14 L Cooling fan relayEngine is running.
Cooling fan is not operating.BATTERY VOLTAGE
(11 - 14V)
Engine is running.
Cooling fan is operating.0-1V
SEF757V
TROUBLE DIAGNOSIS FOR ``OVER HEAT'' (DTC 28)
EC-113

Glow Control System
SYSTEM DESCRIPTION
Crankshaft position sensor (TDC)cEngine speed
ECMcGlow relaycGlow plugs
Engine coolant temperature sensorcEngine coolant temperaturecGlow lamp
When engine coolant temperature is more than 90ÉC (194ÉF), the glow relay turns off, inactivating the quick-
glow control until coolant temperature drops below 70ÉC (158ÉF).
When coolant temperature is lower than 90ÉC (194ÉF):
+Ignition switch ON
After ignition switch has turned to ON, the glow relay turns ON for a certain period of time in relation to
engine coolant temperature, allowing current to ¯ow through glow plug.
+Cranking
The glow relay turns ON, allowing current to ¯ow through glow plug.
+Starting
After engine has started, current continues to ¯ow through glow plug (after-glow mode) for a certain period
in relation to engine coolant temperature.
When engine speed exceeds 2,400 rpm, current ¯ow through glow plug is interrupted.
The glow lamp turns ON for a certain period of time in relation to engine coolant temperature at the time glow
relay is turned ON.
COMPONENT DESCRIPTION
Glow plug
The glow plug is provided with a ceramic heating element to obtain
a high-temperature resistance. It glows in response to a signal sent
from the ECM, allowing current to ¯ow through the glow plug via the
glow relay.
ECM TERMINALS AND REFERENCE VALUE
Remarks: Speci®cation data are reference values and are measured between each terminal andV43(ECCS
ground) with a voltmeter.
TER-
MINAL
NO.WIRE
COLORITEM CONDITIONDATA
(DC Voltage and Pulse
Signal)
16 L/W Glow lampIgnition switch ``ON''
Glow lamp is ``ON''.0 - 1.5V
Ignition switch ``ON''
Glow lamp is ``OFF''.BATTERY VOLTAGE
(11 - 14V)
111 LG/B Glow relay Refer to ``SYSTEM DESCRIPTION''.
SEF857S
TROUBLE DIAGNOSES FOR NON-DETECTABLE ITEMS
EC-151

jA
CHECK COMPONENTS
(Glow relay, Glow plug).
Refer to ``COMPONENT INSPECTION'',
EC-155.
OK
cNG
Replace malfunctioning
component(s).
Disconnect and reconnect harness connec-
tors in the circuit. Then retest.
Trouble is not ®xed.
Check ECM pin terminals for damage and
check the connection of ECM harness con-
nector. Reconnect ECM harness connector
and retest.
INSPECTION END
SYSTEM OPERATION CHECK
Set voltmeter between glow plug and engine body.
1. Quick-glow (Pre-glow) system
a. Turn ignition switch ``ON''.
b. Read voltage.
Voltage:
Battery voltage for about 20* seconds
* Engine coolant temperature is lower than 90ÉC
(194ÉF). [It is lower than 70ÉC (158ÉF) after
warm-up.]
* Repeating ignition switch ``ON'' and ``OFF'' may
change the time.
2. Quick-glow (Cranking) system
a. Disconnect ``S'' terminal for starter motor to prevent engine
from cranking.
b. Read voltage when ignition switch is turned to ``START''.
Voltage:
Battery voltage*
* For about 20 seconds after returning ignition
switch to ``ON''.
SEF700V
SEF780V
.
.
.
.
TROUBLE DIAGNOSES FOR NON-DETECTABLE ITEMS
Glow Control System (Cont'd)
EC-154