PCM INSPECTION [WL-3]

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Without Using the M-MDS

Note

• The PCM terminal voltage can vary with the conditions when measuring and changes due to aged deterioration on the vehicle, causing false diagnosis. Therefore determine comprehensively where the malfunction occurs among the input systems, output systems, and the PCM.

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Terminal voltage table (Reference)

Terminal	Signal	Connected to	Test condition		Voltage (V)	Inspection item
1A	Constant voltage (Vref)	Injection pump EPROM, EGR valve position sensor, Boost sensor, APP sensor	Engine switch ON		Approx. 5	• Inspect related wiring harness • Injection pump EPROM • EGR valve position sensor • Boost sensor • APP sensor
1B	Ground	Body ground	Under any condition		Below 1.0	• Inspect related wiring harness
1C	Power supply	Power supply	Under any condition		B+	• Inspect related wiring harness
1D	Clutch	CPP switch	Clutch pedal depressed		Below 1.0	• Inspect related wiring harness • CPP switch
1D	Clutch	CPP switch	Clutch pedal released		B+	• Inspect related wiring harness • CPP switch
1E	—	—	—		—	—
1F	EGR position	EGR valve	Engine switch ON		Below 1.0	• Inspect related wiring harness • EGR valve
1F	EGR position	EGR valve	EGR valve operating		Approx. 3	• Inspect related wiring harness • EGR valve
1G	Ground	Timer position sensor	Under any condition		Below 1.0	• Inspect related wiring harness
1H	CKP	CKP sensor	Inspection using the wave Profile. (See Inspection Using An Oscilloscope (Reference).)			• Inspect related wiring harness • CKP sensor
1I	Timer position	Timer position sensor	Engine switch ON		Approx. 2.5
1J	IAT	IAT sensor No.1	Engine switch ON	IAT 20 °C {68 °F}	2.3—2.5	• Inspect related wiring harness • IAT sensor No.1
1J	IAT	IAT sensor No.1	Engine switch ON	IAT 30 °C {86 °F}	1.8—2.0	• Inspect related wiring harness • IAT sensor No.1
1K	Constant voltage	Timer position sensor	Engine switch ON		Approx. 5	• Inspect related wiring harness • Timer position sensor
1L	Fuel temp	Fuel temperature sensor	Engine switch ON	Fuel temperature 20 °C {68 °F}	2.4—2.6	• Inspect related wiring harness • Fuel temperature sensor
1L	Fuel temp	Fuel temperature sensor	Engine switch ON	Fuel temperature 70 °C {158 °F}	0.7—0.9	• Inspect related wiring harness • Fuel temperature sensor
1M	Ground	Control sleeve position sensor	Under any condition		Below 1.0	• Inspect related wiring harness • Control sleeve position sensor
1N	Vehicle speed	VSS	Inspection using the wave Profile. (See Inspection Using An Oscilloscope (Reference).)			• Inspect related wiring harness • VSS
1O	Control sleeve position	Control sleeve position sensor	Engine switch ON		Approx. 2.5	• Inspect related wiring harness • Control sleeve position sensor
1P	MAP	Boost sensor	Engine switch ON		Approx. 2.6	• Inspect related wiring harness • Boost sensor
1Q	Constant voltage	Control sleeve position sensor	Engine switch ON		Approx. 2.5	• Inspect related wiring harness • Control sleeve position sensor
1R	APP	APP sensor	Accelerator pedal released		0.5—0.7	• Inspect related wiring harness • APP sensor
1R	APP	APP sensor	Accelerator pedal depressed		3.4—3.8	• Inspect related wiring harness • APP sensor
1S	Injection pump	Injection pump EPROM	Engine switch ON		Approx. 8.5	• Inspect related wiring harness • Injection pump EPROM
1S	Injection pump	Injection pump EPROM	Idle		Approx. 9.5	• Inspect related wiring harness • Injection pump EPROM
1T	ECT	ECT sensor	Engine switch ON	ECT 30 °C {86 °F}	Approx. 2.6	• Inspect related wiring harness • ECT sensor
				ECT 50 °C {122 °F}	Approx. 1.7
				ECT 60 °C {140 °F}	Approx. 1.4
				ECT 80 °C {176 °F}	Approx. 0.8
1U	Starter	Engine switch, Starter relay	Engine switch ON (START) position		B+	• Inspect related wiring harness
1U	Starter	Engine switch, Starter relay	Except for engine switch ON (START) position		Below 1.0	• Inspect related wiring harness
1V	IG1	Engine switch	Engine switch ON and Start position		B+	• Inspect related wiring harness
1V	IG1	Engine switch	Engine switch is other position		Below 1.0	• Inspect related wiring harness
2A	Diagnostic test mode	Data link connector (DLC) (Terminal TEN)	Engine switch ON	Open terminal TEN	B+	• Inspect related wiring harness
2A	Diagnostic test mode	Data link connector (DLC) (Terminal TEN)	Engine switch ON	Short terminal TEN	Below 1.0	• Inspect related wiring harness
2B	Serial communication	Data link connector (DLC) (Terminal KLN)	Because this terminal is for serial communication, good/no good judgement by terminal voltage is not possible. Carry out inspection according to diagnostic trouble codes.			—
2C	APP	APP sensor	Accelerator pedal released		0.5—0.7	• Inspect related wiring harness • APP sensor
2C	APP	APP sensor	Accelerator pedal depressed		3.4—3.8	• Inspect related wiring harness • APP sensor
2D	Injection pump (Np–)	Injection pump	Inspection using the wave Profile. (See Inspection Using An Oscilloscope (Reference).)			• Inspect related wiring harness • Injection pump
2E	Injection pump	Injection pump EPROM	Engine switch ON		Below 1.0	• Inspect related wiring harness
2E	Injection pump	Injection pump EPROM	Idle		Approx. 4	• Inspect related wiring harness
2F	—	—	—		—	—
2G	—	—	—		—	—
2H	—	—	—		—	—
2I	—	—	—		—	—
2J	Tachometer	Tachometer	Engine switch ON		Below 1.0	• Inspect related wiring harness • Tachometer
2J	Tachometer	Tachometer	Idle		B+	• Inspect related wiring harness • Tachometer
2K	Injection pump (Np+)	Injection pump	Inspection using the wave Profile. (See Inspection Using An Oscilloscope (Reference).)			• Inspect related wiring harness • Injection pump
2L	Injection pump	Injection pump EPROM	Engine switch ON		Below 1.0	• Inspect related wiring harness
2L	Injection pump	Injection pump EPROM	Idle		Approx. 4	• Inspect related wiring harness
3A	Main relay control	Main relay	Engine switch ON		Below 1.0	• Inspect related wiring harness • Main relay
3A	Main relay control	Main relay	Engine switch OFF		B+	• Inspect related wiring harness • Main relay
3B	—	—	—		—	—
3C	Cooling fan	Cooling fan switch	Engine switch ON	A/C operating	B+	• Inspect related wiring harness
3C	Cooling fan	Cooling fan switch	Engine switch ON	A/C not operating	Approx. 0.87	• Inspect related wiring harness
3D	IAT	MAF sensor/IAT sensor No.2	Engine switch ON	IAT 20 °C {68 °F}	2.3—2.5	• Inspect related wiring harness • MAF sensor/IAT sensor No.2
3D	IAT	MAF sensor/IAT sensor No.2	Engine switch ON	IAT 30 °C {86 °F}	1.8—2.0
3E	—	—	—		—	—
3F	—	—	—		—	—
3G	—	—	—		—	—
3H	—	—	—		—	—
3I	—	—	—		—	—
3J	—	—	—		—	—
3K	—	—	—		—	—
3L	—	—	—		—	—
3M	—	—	—		—	—
3N	—	—	—		—	—
3O	Idle switch	Idle switch	Accelerator pedal released		Below 1.0	• Inspect related wiring harness • Idle switch
3O	Idle switch	Idle switch	Accelerator pedal depressed		B+	• Inspect related wiring harness • Idle switch
3P	—	—	—		—	—
4A	Ground	Body ground	Under any condition		Below 1.0	• Inspect related wiring harness
4B	Ground	Body ground	Under any condition		Below 1.0	• Inspect related wiring harness
4C	B+	Main relay	Main relay ON		B+	• Inspect related wiring harness • Main relay
4C	B+	Main relay	Main relay OFF		Below 1.0	• Inspect related wiring harness • Main relay
4D	B+	Main relay	Main relay ON		B+	• Inspect related wiring harness • Main relay
4D	B+	Main relay	Main relay OFF		Below 1.0	• Inspect related wiring harness • Main relay
4E	MAF	MAF sensor/IAT sensor No.2	Engine switch ON		Below 1.0	• Inspect related wiring harness • MAF sensor/IAT sensor No.2
4E	MAF	MAF sensor/IAT sensor No.2	Idle		1.6—2.0
4F	—	—	—		—	—
4G	—	—	—		—	—
4H	—	—	—		—	—
4I	EGR control solenoid valve	EGR control solenoid valve	Engine speed is 3,000 rpm		B+	• Inspect related wiring harness • EGR control solenoid valve
4I	EGR control solenoid valve	EGR control solenoid valve	Idle		Below 1.0
4J	—	—	—		—	—
4K	DTC output	Data link connector (DLC) (Terminal FEN)	No DTC output		Below 1.0	• Inspect related wiring harness
4K	DTC output	Data link connector (DLC) (Terminal FEN)	DTC output		0—B+	• Inspect related wiring harness
4L	A/C	A/C relay	A/C operating		Below 1.0	• Inspect related wiring harness • A/C relay
4L	A/C	A/C relay	A/C not operating		B+	• Inspect related wiring harness • A/C relay
4M	—	—	—		—	—
4N	—	—	—		—	—
4O	—	—	—		—	—
4P	—	—	—		—	—
4Q	EGRA	EGR solenoid valve (Vent)	Engine switch ON		B+	• Inspect related wiring harness • EGR solenoid valve (Vent)
4Q	EGRA	EGR solenoid valve (Vent)	Idle		Below 1.0
4R	—	—	—		—	—
4S	Glow indicator light	Glow indicator light	Engine switch OFF		Below 1.0	• Inspect related wiring harness • Glow indicator light
			Engine switch is ON and within approx. 4.5 sec. (25 °C {77 °F})		Below 1.0
			Over 4.5 seconds (25 °C {77 °F}) after turning engine switch ON.		B+
4T	EGRV	EGR solenoid valve (Vacuum)	Engine switch ON		B+	• Inspect related wiring harness • EGR solenoid valve (Vacuum)
4U	TCV	Timer control valve	Engine switch ON		B+	• Inspect related wiring harness • Timer control valve
4U	TCV	Timer control valve	Idle		Below 1.0	• Inspect related wiring harness • Timer control valve
4V	Glow system	Glow relay	ECT is below 60 °C {140 °F}	For less than approx. 15 seconds after turning engine switch ON.	B+	• Inspect related wiring harness • Glow relay
				Over approx. 15 seconds after turning engine switch ON.	Below 1.0
				For less than 10 minutes starting engine.	B+
				Over 10 minutes after starting engine.	Below 1.0
				While cranking	B+
			ECT is above 60 °C {140 °F}	For less than approx. 2 seconds after turning engine switch ON.	B+
				Over approx. 2 seconds after turning engine switch ON.	Below 1.0
				While cranking	B+
4W	FCV	Fuel cut solenoid valve	Engine switch ON		Below 1.0	• Inspect related wiring harness • Fuel cut solenoid valve
4W	FCV	Fuel cut solenoid valve	Idle		B+	• Inspect related wiring harness • Fuel cut solenoid valve
4X	Electronic governor voltage	Electronic governor	Engine switch ON		B+	• Inspect related wiring harness
4Y	Electronic governor	Electronic governor	Engine switch ON		B+	• Inspect related wiring harness
4Z	—	—	—		—	—

Inspection Using An Oscilloscope (Reference)

CKP signal

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PCM terminals

• 1H (+)—body ground (–)

Oscilloscope setting

• 2 V/DIV (Y), 10 ms/DIV (X), DC range

Vehicle condition

• Idle after warm up

Vehicle speed signal

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PCM terminals

• 1J (+)—body ground (–)

Oscilloscope setting

• 1 V/DIV (Y), 2.5 ms/DIV (X), DC range

Vehicle condition

• Vehicle speed is 32 km/h {20 mph}.

Injection pump (speed sensor) signal

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PCM terminals

• 2K (+)—2D (–)

Oscilloscope setting

• 1 V/DIV (Y), 5 ms/DIV (X), DC range

Vehicle condition

• Idle after warm up

Electronic governor signal

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PCM terminals

• 4Y (+)—body ground (–)

Oscilloscope setting

• 5 V/DIV (Y), 400 us/DIV (X), DC range

Vehicle condition

• Idle after warm up

Using M-MDS

Caution

• The PCM terminal voltage vary with change in measuring conditions and vehicle conditions.

Always carry out a total inspection of the input systems, output systems, and PCM to determine the cause of trouble. Otherwise, diagnosis will be incorrect.

Note

• PIDs for the following parts are not available on this model. Go to the appropriate part inspection page.

― Electronic governor

― Fuel pump speed sensor

― Injection pump EPROM

― EGR control solenoid valve

― Tachometer

1. Connect the M-MDS to the DLC-2. (See ON-BOARD DIAGNOSTIC TEST [WL-3].)

2. Measure the PID value.

• If PID value is not within the specification, follow the instructions in ACTION column.

3. Turn the engine switch to the ON position (Engine off).

Note

• The PID/DATA MONITOR function monitors the calculated value of the input/output signals in the PCM. Therefore, an output device malfunction is not directly indicated as a malfunction of the monitored value for the output device. If a monitored value of an output device is out of specification, inspect the monitored value of the input device related to the output control.

• For input/output signals except those of the monitoring items, use a voltmeter to measure the PCM terminal voltage.

• The simulation items that are used in the ENGINE CONTROL SYSTEM OPERATION INSPECTION are as follows.

― ACCS, GOVERNOR, EGRA, EGRV, FSOV, GP_LMP, GPC, TCV

PID Monitor Table (Reference)

Monitor item (Definition)	Unit/Condition				Condition/Specification	Action	PCM terminal
ACCS (Air conditioning compressor cycling switch)	ON/OFF				Engine switch is ON: OFF A/C switch is ON at idle: ON	Inspect following PIDs: TP, ECT, ACSW, CPP/PNP, VSS, STARTER. Inspect A/C relay.	4L
ACSW (A/C switch)	ON/OFF				A/C switch is ON with engine switch ON: ON A/C switch is OFF with engine switch ON: OFF	Inspect refrigerant pressure switch.	3C
ARPMDES (Target engine speed)	rpm				A/C ON: 750 rpm Other: 720 rpm	Inspect A/C switch.	—
BARO (Barometric pressure)	kPa	Bar		psi	Elevation 0—400 m {0—1310 ft}: 100—103 kPa {1.00—1.03 Bar, 14.5—14.9 psi}	Replace PCM.	—
BARO (Barometric pressure)	V				Elevation 0—400 m {0—1310 ft}: approx. 4.0 V	Replace PCM.	—
CPP/PNP (Neutral/clutch pedal position)	ON/OFF				Neutral position or clutch pedal is depressed: ON Others: OFF	Inspect neutral switch and CPP switch.	1D
CSP (Control sleeve signal voltage)	V				Engine switch is wiring harness: below 1.0 V Engine switch is ON or idle: approx. 2.5 V	Inspect control sleeve (CS) sensor.	1Q
ECT (Engine coolant temperature)	°C		°F		ECT is 20°C {68°F}: 20°C {68°F} ECT is 85°C {185°F}: 85°C {185°F}	Inspect ECT sensor.	1T
ECT (Engine coolant temperature)	V				ECT is 20°C {68°F}: 3.0—3.2 V ECT is 85°C {185°F}: 0.7—0.9 V	Inspect ECT sensor.	1T
EGRA (EGR solenoid valve (vent))	%				Engine switch is ON: 0—100% Idle: 0—100%	Inspect following PIDs: ECT, TP, IDLE SW, MAF, IAT, RPM, EGRVP. Inspect EGR solenoid valve (vent).	4Q
EGRV (EGR solenoid valve (vacuum))	%				Engine switch is ON: 0—100% Idle: 0—100%	Inspect following PIDs: ECT, TP, IDLE SW, MAF, IAT, RPM, EGRVP. Inspect EGR solenoid valve (vent).	4T
EGRVP (EGR valve position)	V				Engine switch is ON: Below 1.0 Idle: above 3.0 V	Inspect EGR valve position sensor.	1F
FLT (Fuel temperature sensor)	°C		°F		Fuel temperature is 20°C {68°F}: 20°C {68°F}:	Inspect fuel temperature sensor.	1L
FLT V (Fuel temperature signal voltage)	V				Fuel temperature is 20°C {68°F}: 2.4—2.6 V Fuel temperature is 70°C {158°F}: 0.7—0.9 V	Inspect fuel temperature sensor.	1L
FSOV (Fuel cut solenoid valve)	ON/OFF				Idle: ON Engine switch is ON: ON Engine speed is above 5,100 rpm: OFF DTC P1182, P0251, P0606, P1226 is detected: OFF	Perform applicable DTC troubleshooting	4W
GPC (Glow plug relay)	ON/OFF				ECT below 60°C {140°F} • For 15 s after engine switch ON: ON • After 15 s elapse from engine switch ON: OFF • For 6.5 s—10 min after engine started: ON • After 6.5 s—10 min elapse from engine started: OFF ECT above 60°C {140°F} • For 6.5 s after engine switch ON: ON • After 6.5 s elapse from engine switch ON: OFF	Inspect following PIDs: ECT, VSS, VPWR. Inspect glow plug relay.	4V
GP_LMP (Glow indicator light)	ON/OFF				For 4s after engine switch ON (ECT is 20°C {68°F}): ON	Inspect instrument cluster.	4S
IAT (Intake air temperature (IAT sensor No.1))	°C		°F		IAT is 20°C {68°F}: 20°C {68°F} IAT is 30°C {86°F}: 30°C {86°F}	Inspect IAT sensor No.1.	1J
IAT (Intake air temperature (IAT sensor No.1))	V				IAT is 20°C {68°F}: 2.3—2.5 V IAT is 30°C {86°F}: 1.8—2.0 V	Inspect IAT sensor No.1.	1J
IAT2 (Intake air temperature (IAT sensor No.2))	°C		°F		IAT is 20°C {68°F}: 20°C {68°F} IAT is 30°C {86°F}: 30°C {86°F}	Inspect MAF sensor/IAT sensor No.2.	3D
IAT2 (Intake air temperature (IAT sensor No.2))	V				IAT is 20°C {68°F}: 2.3—2.5 V IAT is 30°C {86°F}: 1.8—2.0 V	Inspect MAF sensor/IAT sensor No.2.	3D
IDLE SW (Idle switch)	ON/OFF				Accelerator pedal is released: ON Other: OFF	Inspect idle switch.	3O
MAF (mass airflow amount)	V				Engine switch is ON: below 1.0 V Idle: 1.6—2.0 V	Inspect MAF sensor/IAT sensor No.2.	4E
MAINRLY (Main relay)	ON/OFF				Engine switch is ON: ON Other: OFF	Inspect engine switch.	3A
MAP (Boost sensor)	kPa	Bar		psi	Idle: 101kPa {1.01 Bar, 14.7psi}	Inspect boost sensor.	1P
MAP (Boost sensor)	V				Idle: approx. 2.6V	Inspect boost sensor.	1P
MIL (Malfunction indicator lamp)	ON/OFF				Engine switch is ON: ON Idle: OFF	Perform applicable DTC troubleshooting	—
RPM (Engine speed)	rpm				A/C ON: 725—775rpm Other: 695—745rpm	Inspect following PIDs: TP, MAP, RPM	1H
SELTESTDTC (Diagnostic trouble codes)	—				—	Perform applicable DTC troubleshooting	—
STARTER (Engine switch)	ON/OFF				Engine switch at START: ON Other: OFF	Inspect engine switch.	1U
TCV (Timer control valve signal)	%				Idle: 99.6 % Engine speed 2,000 rpm: 35 %	Inspect timer control valve	4U
TPS (Timer position sensor signal)	%				Engine switch is ON: 0% Idle: 100%	Inspect timer position sensor.	1K
TEST (TEN terminal (in DLC))	ON/OFF				Terminal TEN (DLC) is shorted to ground: ON Terminal TEN (DLC) is open: OFF	Inspect wiring from DLC terminal TEN to PCM terminal 2A.	2A
TP (Accelerator pedal position sensor No.1)	V				Accelerator pedal is depressed: 3.4—3.8 V Accelerator pedal is released:0.5—0.7 V	Inspect accelerator pedal position sensor.	1R
TP2 V (Accelerator pedal position sensor No.2)	V				Accelerator pedal is depressed: 3.4—3.8 V Accelerator pedal is released: 0.5—0.7 V	Inspect accelerator pedal position sensor.	2C
VPWR (Battery positive voltage)	V				Engine switch is ON: B+ Other: below 1.0 V	Inspect main relay.	4C
VSS (Vehicle speed)	km/h		mph		Vehicle speed is 20 km/h {12.5 mph}: 20 km/h {12.5 mph} Vehicle speed is 40 km/h {25 mph}: 40 km/h {25 mph}	Inspect Instrument cluster.	1N