Page 843 of 2493

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-693 *3
Accelerator position switch (Idle)
circuit*a, *c 1 1 1 1 1
EC-577
*b 1 1 1 *4
Ignition switch circuit*a 1 111
EC-560
*b*5
Power supply for ECM circuit*a 1 111
EC-560
*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 DESCRIPTIONYD
Symptom Matrix Chart (Cont'd)
EC-547
Page 844 of 2493
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 illuminates.
Can be detected by CONSULT-II?BLACK SMOKE
WHITE SMOKEWarranty symptom code AG AH AJ AK AL AM AP HA
ENGINE CONTROL
Start signal circuit *a, *b EC-693 *3
Accelerator position switch (Idle) circuit*a, *c
EC-577
*b 1 1 *4
Ignition switch circuit*a
EC-560
*b*5
Power supply for ECM circuit*a
1 1 EC-560
*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 DESCRIPTIONYD
Symptom Matrix Chart (Cont'd)
EC-548
Page 845 of 2493

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-686
*c 1 1 1 *6
Glow relay circuit*a 1111
EC-677*7
*b*8
ECM relay (Self-shutoff) circuit*a 1 111
EC-666
*b*9
ECM, Connector circuit *a, *b2222222222222EC-664,
604
Air conditioner relay circuit*a
EC-700*10
*b 1 *11
Air conditioner switch circuit*a, *c
EC-700*11
*b*12
1 - 5: The numbers refer to the order of inspection.
(continued on next page)
*a: Open
*b: Short
*c: Ground short
*d: Noise
*6: Does not stop operating.
*7: Glow lamp does not turn on.
*8: Glow lamp does not turn off.
*9: Ground short makes engine unable to stop.
*10: Air conditioner does not operate.
*11: Air conditioner does not stop operating.
*12: Air conditioner does not work.
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONYD
Symptom Matrix Chart (Cont'd)
EC-549
Page 846 of 2493

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 illuminates.
Can be detected by CONSULT-II?BLACK SMOKE
WHITE SMOKEWarranty symptom code AG AH AJ AK AL AM AP HA
ENGINE CONTROL
EGR volume control valve circuit*a, *b
EC-686
*c 1 *6
Glow relay circuit*a 1
EC-677*7
*b*8
ECM relay (Self-shutoff) circuit*a
EC-666
*b*9
ECM, Connector circuit *a, *b22222222222EC-664,
604
Air conditioner relay circuit*a
EC-700*10
*b*11
Air conditioner switch circuit*a, *c
EC-700*11
*b*12
1 - 5: The numbers refer to the order of inspection.
*a: Open
*b: Short
*c: Ground short
*d: Noise
*6: Does not stop operating.
*7: Glow lamp does not turn on.
*8: Glow lamp does not turn off.
*9: Ground short makes engine unable to stop.
*10: Air conditioner does not operate.
*11: Air conditioner does not stop operating.
*12: Air conditioner does not work.
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONYD
Symptom Matrix Chart (Cont'd)
EC-550
Page 850 of 2493

SEF289H
ECM Terminals and Reference ValueNJEC0636PREPARATIONNJEC0636S01ECM is locating beside of blower unit.
1. Remove the ECM bracket fixing.
2. Remove ECM harness protector.
3. Disconnect negative battery terminal.
SEF883Y
4. Connect a break out box (SST) between the ECM and ECM
harness connectors.
+Use extreme care not to touch 2 pins at one time.
+Data is for comparison and may not be exact.
+Be sure ECM unit is properly grounded before checking.
ECM HARNESS CONNECTOR TERMINAL LAYOUTNJEC0636S02
SEF435Z
ECM INSPECTION TABLENJEC0636S03Remarks: Specification data are reference values and are mea-
sured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/
output voltage. Doing so may result in damage to the ECM's
transistor. Use a ground other than ECM terminals, such as
the ground.
TERMI-
NAL
NO.WIRE
COLORITEM CONDITIONDATA (DC Voltage and Pulse
Signal)
104
105
106B
B
BECM ground[Engine is running]
+Idle speedApproximately 0V
107
108
109R
R
RPower supply for ECM[Ignition switch ªONº]BATTERY VOLTAGE
(11 - 14V)
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONYD
ECM Terminals and Reference Value
EC-554
Page 858 of 2493

DIAGNOSTIC PROCEDURENJEC0641
1 INSPECTION START
Start engine.
Is engine running?
YesorNo
Ye s©GO TO 13.
No©GO TO 2.
2 CHECK ECM POWER SUPPLY CIRCUIT-I
1. Turn ignition switch ªONº.
2. Check voltage between ECM terminal 507 and ground with CONSULT-II or tester.
SEF895Y
OK or NG
OK©GO TO 4.
NG©GO TO 3.
3 DETECT MALFUNCTIONING PART
Check the following.
+Harness connectors M74, F112
+Fuse block (J/B) connector M1
+10A fuse
+Harness for open or short between ECM and fuse
©Repair open circuit or short to ground or short to power in harness or connectors.
4 CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch ªOFFº.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminals 104, 105, 106 and engine ground. Refer to Wiring Diagram.
Continuity should exist.
4. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 5.
NG©Repair open circuit or short to ground or short to power in harness or connectors.
TROUBLE DIAGNOSIS FOR POWER SUPPLYYD
Main Power Supply and Ground Circuit (Cont'd)
EC-562
Page 859 of 2493

5 CHECK ECM POWER SUPPLY CIRCUIT-II
1. Reconnect ECM harness connector.
2. Turn ignition switch ªONº and then ªOFFº.
3. Check voltage between ECM terminals 107, 108, 109 and ground with CONSULT-II or tester.
SEF896Y
OK or NG
OK©Check electronic control fuel injection pump power supply circuit. Refer to ªDiagnostic
Procedureº, EC-662.
NG (Battery voltage
does not exist.)©GO TO 6.
NG (Battery voltage
exists for more than a
few seconds.)©GO TO 10.
6 CHECK ECM POWER SUPPLY CIRCUIT-III
1. Disconnect ECM relay. (For ECM relay location, refer to ªEngine Control Component Parts Locationº.)
2. Check voltage between relay terminals 1, 6 and ground with CONSULT-II or tester.
SEF399Y
OK or NG
OK©GO TO 8.
NG©GO TO 7.
7 DETECT MALFUNCTIONING PART
Check the following.
+20A fuse
+10A fuse
+Harness for open or short between ECM relay and battery
©Repair open circuit or short to ground or short to power in harness or connectors.
TROUBLE DIAGNOSIS FOR POWER SUPPLYYD
Main Power Supply and Ground Circuit (Cont'd)
EC-563
Page 861 of 2493

13 CHECK ECM POWER SUPPLY CIRCUIT-V
1. Turn ignition switch ªOFFº.
2. Disconnect ECM relay. (For ECM relay location, refer to ªEngine Control Component Parts Locationº.)
3. Disconnect ECM harness connector.
4. Check harness continuity between ECM terminals 107, 108, 109 and ECM relay terminal 7. Refer to Wiring Diagram.
Continuity should exist.
5. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 15.
NG©GO TO 14.
14 DETECT MALFUNCTIONING PART
Check the following.
+Harness connectors E75, F36
+Harness for open or short between ECM and ECM relay
©Repair open circuit or short to ground or short to power in harness or connectors.
15 CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between ECM terminals 104, 105, 106 and engine ground. Refer to Wiring Diagram.
Continuity should exist.
2. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 16.
NG©Repair open circuit or short to ground or short to power in harness or connectors.
16 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-559.
©INSPECTION END
TROUBLE DIAGNOSIS FOR POWER SUPPLYYD
Main Power Supply and Ground Circuit (Cont'd)
EC-565