Toyota 4Runner: Terminals Of Ecu

Toyota 4Runner Service Manual / Vehicle Interior / Heating / Air Conditioning / Air Conditioning System(for Manual Air Conditioning System) / Terminals Of Ecu

TERMINALS OF ECU

1. CHECK NO. 1 AIR CONDITIONING AMPLIFIER ASSEMBLY

(a) Disconnect the F42 No. 1 air conditioning amplifier assembly connector.

(b) Measure the voltage and resistance according to the value(s) in the table below.

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
F42-21 (B) - F42-14 (GND)	V - W-B	Battery power source	Always	11 to 14 V
F42-1 (IG+) - F42-14 (GND)	L - W-B	Ignition power supply	Ignition switch ON	11 to 14 V
F42-1 (IG+) - F42-14 (GND)	L - W-B	Ignition power supply	Ignition switch off	Below 1 V
F42-14 (GND) - Body ground	W-B - Body ground	Ground for main power supply	Always	Below 1 Ω

If the result is not as specified, there may be a malfunction on the wire harness side.

(d) Measure the voltage according to the value(s) in the table below.

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
F42-3 (PTC1) - Body ground	V - Body ground	PTC NO. 1 relay operation signal	Engine running (1250 rpm or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 79°C (174°F) or less Headlight dimmer switch off Blower switch on	11 to 14 V*
F42-4 (PTC3) - Body ground	P - Body ground	PTC NO. 3 relay operation signal	Engine running (1250 rpm or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 73°C (163°F) or less Headlight dimmer switch off Blower switch on	11 to 14 V*
F42-5 (TAM) - F42-13 (SG-2)	V - G	Cooler thermistor (ambient temperature sensor) signal	Ignition switch ON Ambient temperature 25°C (77°F)	1.35 to 1.75 V
F42-5 (TAM) - F42-13 (SG-2)	V - G	Cooler thermistor (ambient temperature sensor) signal	Ignition switch ON Ambient temperature 40°C (104°F)	0.9 to 1.2 V
F42-8 (LOCK) - F42-13 (SG-2)	R - G	A/C compressor lock sensor signal	Engine running Blower switch LO A/C switch on	Pulse generation (See waveform 1)
F42-9 (PRE) - Body Ground	G - Body Ground	No. 1 pressure switch signal	Ignition switch ON Refrigerant pressure normal (below 3140 kPa [32.0 kgf/cm2, 455 psi] and higher than 196 kPa [2.0 kgf/cm2, 28 psi])	Below 1 V
F42-9 (PRE) - Body Ground	G - Body Ground	No. 1 pressure switch signal	Ignition switch ON Refrigerant pressure abnormal (below 196 kPa [2.0 kgf/cm2, 28 psi] or higher than 3140 kPa [32.0 kgf/cm2, 455 psi])	4.69 V or higher
F42-17 (AC1) - F42-14 (GND)	LG - W-B	Compressor operation signal	Ignition switch ON A/C switch on	Below 1 V
F42-18 (MHTR) - F42-14 (GND)	G - W-B	MIR HTR relay signal	Ignition switch ON Mirror heater switch on	Below 1 V
F42-20 (MGC) - F42-14 (GND)	R - W-B	Magnet clutch assembly operation signal	Ignition switch ON Blower switch LO A/C switch on	Below 1 V
F42-22 (PTC2) - Body ground	LG - Body ground	PTC NO. 2 relay operation signal	Engine running (1250 rpm or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 76°C (169°F) or less Headlight dimmer switch off Blower switch on	11 to 14 V*
F42-23 (BLW) - F42-14 (GND)	LG - W-B	Blower with fan motor sub-assembly control signal	Ignition switch ON Blower switch LO	Pulse generation (See waveform 2)
F42-25 (ALT) - F42-14 (GND)	L - W-B	Generator signal (PTC heater control)	Engine started	Pulse generation
F42-27 (ACT) - F42-14 (GND)	SB - W-B	Compressor operation signal	Ignition switch ON A/C switch on	4.75 to 5.25 V
z15-2 (BUS G) - Body ground	-	Ground for BUS IC	Always	Below 1 V
z15-3 (BUS) - z15-2 (BUS G)	-	BUS IC control signal	Ignition switch ON	Pulse generation
z15-4 (B BUS) - z15-2 (BUS G)	-	Power supply for BUS IC	Always	11 to 14 V
z15-6 (TE) - z15-5 (SG-3)	-	No. 1 cooler thermistor signal	Ignition switch ON Evaporator temperature 0°C (32°F)	1.7 to 2.1 V
z15-6 (TE) - z15-5 (SG-3)	-	No. 1 cooler thermistor signal	Ignition switch ON Evaporator temperature 15°C (59°F)	0.9 to 1.3 V

HINT:

*: After the measurement conditions are met, wait 30 seconds before performing measurements.

If the result is not as specified, the No. 1 air conditioning amplifier assembly may have a malfunction.

(e) Using an oscilloscope, check waveform 1.

A/C Compressor Lock Sensor Signal

Item	Content
Terminal No. (Symbol)	F42-8 (LOCK) - F42-13 (SG-2)
Tool Setting	200 mV/DIV., 10 ms./DIV.
Condition	Engine running A/C switch on Blower switch LO

(f) Using an oscilloscope, check waveform 2.

Blower Motor Control Signal

Item	Content
Terminal No. (Symbol)	F42-23 (BLW) - F42-14 (GND)
Tool Setting	1 V/DIV., 500 μs/DIV.
Condition	Ignition switch ON Blower switch LO

HINT:

When the blower level is increased, the duty ratio changes accordingly.

2. CHECK HEATER CONTROL ASSEMBLY

(a) Disconnect the F29 heater control assembly connector.

(b) Measure the resistance and voltage according to the value(s) in the table below.

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
F29-4 (IG+) - F29-11 (GND)	L - W-B	IG power supply	Ignition switch ON	11 to 14 V
F29-11 (GND) - Body ground	W-B - Body ground	Ground	Always	Below 1 Ω

If the result is not as specified, there may be a malfunction on the wire harness side.

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