Page 50 of 192

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
Page 52 of 192

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
Page 54 of 192
MONITOR ITEM CONDITION SPECIFICATION
COOLING FAN+When cooling fan is stopped. OFF
+When cooling fan operates. ON
I/C FAN RLY+When charge air cooler fan is stopped. OFF
+When charge air cooler fan operates. ON
EGRC SOL/V A+Engine: After warming up
+Air conditioner switch: ``OFF''
+Shift lever: ``N''
+No-loadIdle ON
Revving engine from idle to 3,750 rpm OFF
EGRC SOL/V B+Engine: After warming up
+Air conditioner switch: ``OFF''
+Shift lever: ``N''
+No-loadIdle ON
Revving engine from idle to 2,600 rpm OFF
THROT RLY+Engine: After warming up
+Air conditioner switch: ``OFF''
+Shift lever: ``N''
+No-loadIdle ON
Revving engine from idle to 2,500 rpm OFF
TROUBLE DIAGNOSIS Ð General Description
CONSULT Reference Value in Data Monitor
Mode (Cont'd)
EC-52
Page 63 of 192

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
103 L/Y EGRC-solenoid valve AEngine is running.
(Warm-up condition)
Idle speed0-1V
Engine is running.
(Warm-up condition)
Engine is revving from idle up to 3,750 rpm.BATTERY VOLTAGE
(11 - 14V)
104
11 0L/WInjection timing control
valveEngine is running.
(Warm-up condition)
Idle speedBATTERY VOLTAGE
(11 - 14V)
SEF729V
Engine is running.(Warm-up condition)
Engine speed is 2,000 rpm.BATTERY VOLTAGE
(11 - 14V)
SEF730V
106
11 2
11 8B ECCS groundEngine is running.
Idle speedApproximately 0V
109 BR/Y EGRC-solenoid valve BEngine is running.
(Warm-up condition)
Idle speed0-1V
Engine is running.
(Warm-up condition)
Engine is revving from idle up to 2,600 rpm.BATTERY VOLTAGE
(11 - 14V)
TROUBLE DIAGNOSIS Ð General Description
ECM Terminals and Reference Value (Cont'd)
EC-61
Page 158 of 192

EGRC-Solenoid Valve A, B and Throttle Control
Solenoid Valve
SYSTEM DESCRIPTION
Camshaft position sensor (TDC)cEngine speed
ECM
(ECCS-D
control
module)cEGRC-solenoid valve A
Accelerator position sensorcAccelerator positioncEGRC-solenoid valve B
Engine coolant temperature sensorcEngine coolant temperaturecThrottle control solenoid valve
Ignition switchcStart signal
Mass air ¯ow sensor
cAmount of intake air
The ECM receives signals sent from the engine coolant tempera-
ture sensor, crankshaft position sensor (TDC), ignition switch, mass
air ¯ow sensor and accelerator position sensor to determine engine
speed and operating conditions. Based on these signals, the ECM
controls EGR control solenoid valve (A and B) operation and
throttle control solenoid valve operation.
Engine coolant
temperature
ÉC (ÉF)LoadEGRC-solenoid valve
Throttle control
solenoid valveEGR valveThrottle control
valveAmount of EGR
gas
AB
Below 70 (158) AnyOFF
(Closed)OFF
(Closed)OFF
(Closed)Fully closed Fully open Ð
Above 70 (158)Low loadON
(Open)ON
(Open)ON
(Open)Fully open Closed Large
Medium load-1ON
(Open)ON
(Open)OFF
(Closed)Fully open Fully open Medium
Medium load-2ON
(Open)OFF
(Closed)OFF
(Closed)Half open Fully open Small
High loadOFF
(Closed)OFF
(Closed)OFF
(Closed)Fully closed Fully open Ð
COMPONENT DESCRIPTION
The EGRC-solenoid valves A and B control vacuum pressure act-
ing on the EGR valve. The EGR control valve will then be fully
opened, half-opened or fully closed, as required.
The throttle control solenoid valve controls vacuum pressure acting
on the throttle chamber. Thus, intake air passages are opened or
closed in relation to exhaust gas and intake air. Utilizing the rela-
tionship between exhaust gas pressure and intake air pressure
control, the amount of EGR (exhaust gas recirculated) is regulated
in three stages Ð large, medium, small.
SEF784V
TROUBLE DIAGNOSES FOR NON-DETECTABLE ITEMS
EC-156
Page 159 of 192

CONSULT REFERENCE VALUE IN DATA MONITOR MODE
Remarks: Speci®cation data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
EGRC SOL/V A+Engine: After warming up
+Air conditioner switch: ``OFF''
+Shift lever: ``N''
+No-loadIdle ON
Revving engine from idle to 3,750
rpmOFF
EGRC SOL/V B+Engine: After warming up
+Air conditioner switch: ``OFF''
+Shift lever: ``N''
+No-loadIdle ON
Revving engine from idle to 2,600
rpmOFF
THROT RLY+Engine: After warming up
+Air conditioner switch: ``OFF''
+Shift lever: ``N''
+No-loadIdle ON
Revving engine from idle to 2,500
rpmOFF
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)
1WThrottle control solenoid
valveEngine is running.
(Warm-up condition)
Idle speedApproximately 0.4V
Engine is running.
(Warm-up condition)
Revving engine from idle to 2,500 rpmBATTERY VOLTAGE
(11 - 14V)
103 L/Y EGRC-solenoid valve AEngine is running.
(Warm-up condition)
Idle speed0-1V
Engine is running.
(Warm-up condition)
Revving engine from idle up to 3,750 rpm.BATTERY VOLTAGE
(11 - 14V)
109 BR/Y EGRC-solenoid valve BEngine is running.
(Warm-up condition)
Idle speed0-1V
Engine is running.
(Warm-up condition)
Revving engine from idle up to 2,600 rpm.BATTERY VOLTAGE
(11 - 14V)
TROUBLE DIAGNOSES FOR NON-DETECTABLE ITEMS
EGRC-Solenoid Valve A, B and Throttle Control
Solenoid Valve (Cont'd)
EC-157
Page 160 of 192
TEC442
TROUBLE DIAGNOSES FOR NON-DETECTABLE ITEMS
EGRC-Solenoid Valve A, B and Throttle Control
Solenoid Valve (Cont'd)
EC-158
Page 161 of 192

DIAGNOSTIC PROCEDURE
INSPECTION START
CHECK OVERALL FUNCTION.
1. Start engine and warm it up to normal
operating temperature.
2. Perform diagnostic test mode II (Self-
diagnostic results).
Make sure that diagnostic trouble code
No. 55 is displayed.
3. Make sure that EGR valve spring
moves up and down (Use your ®nger)
under the following conditions.
At idle:
Spring moves up and down.
Revving engine from idle to 3,800
rpm:
Spring does not move.
4. Make sure that throttle control valve rod
moves up and down under the following
conditions.
At idle:
Rod moves up and down.
Revving engine from idle to 2,500
rpm:
Rod does not move.
NG
cOK
INSPECTION END
CHECK VACUUM SOURCES TO EGR
VALVE AND THROTTLE CONTROL
VALVE.
1. Disconnect vacuum hose to EGR valve.
2. Make sure that vacuum exists under
the following conditions.
At idle:
Vacuum should exist.
Revving engine from idle to 3,800
rpm:
Vacuum should not exist.
3. Disconnect vacuum hose to throttle
control valve.
4. Make sure that vacuum exists under
the following conditions.
At idle:
Vacuum should exist.
Revving engine from idle to 2,500
rpm:
Vacuum should not exist.
NG
cOK
CHECK COMPONENTS
(EGR valve and throttle
control valve).
(See page EC-162.)
NG
Replace malfunctioning
component(s).
jA
SEF702V
SEF703V
SEF704V
SEF705V
.
.
.
.
TROUBLE DIAGNOSES FOR NON-DETECTABLE ITEMS
EGRC-Solenoid Valve A, B and Throttle Control
Solenoid Valve (Cont'd)
EC-159