Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Terminals Of Ecu

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Vehicle Interior / Heating / Air Conditioning / Air Conditioning System / Terminals Of Ecu

TERMINALS OF ECU

AIR CONDITIONING AMPLIFIER ASSEMBLY (w/o Rear Air Conditioning System)

*A

w/o Seat Heater

*B

w/ Seat Heater

HINT:

Check from the rear of the connector while it is connected to the air conditioning amplifier assembly.

Terminal No.

(Symbol)

Wiring Color

Terminal Description

Condition

Specified Condition

J42-1 (SG-1) - Body ground

L - Body ground

Ground for cooler (room temp. sensor) thermistor

Always

Below 1 V

J42-2 (SG-2) - Body ground

B - Body ground

Ground for cooler (ambient temp. sensor) thermistor, A/C lock sensor, smog ventilation sensor*2

Always

Below 1 V

J42-3 (SG-4) - Body ground

BE - Body ground

Ground for air conditioner pressure sensor

Always

Below 1 V

J42-6 (S5-3) - J42-2 (SG-2)

W - B

Power supply for air conditioner pressure sensor

Engine switch on (IG)

4.75 to 5.25 V

Engine switch off

Below 1 V

J42-9 (MGC) - J43-4 (GND)

R - W-B

Magnetic clutch operation signal
  • Engine running
  • Blower switch: LO
  • A/C switch: Off

11 to 14 V
  • Engine running
  • Blower switch: LO
  • A/C switch: On

Below 1 V

J42-10 (PTC2) - J43-4 (GND)*1

G - W-B

Quick heater assembly operation signal
  • Engine running
  • Combination switch assembly (ECO mode switch) off
  • Temperature setting: MAX HOT
  • Ambient temperature: 0°C (32°F) or lower
  • Engine coolant temperature: 70°C (158°F) or lower
  • Light control switch off
  • Blower switch: On

Below 1 V
  • Engine running
  • Combination switch assembly (ECO mode switch) off
  • Temperature setting: MAX HOT
  • Ambient temperature: 0°C (32°F) or lower
  • Engine coolant temperature: 70°C (158°F) or lower
  • Light control switch off
  • Blower switch: Off

11 to 14 V

J42-11 (PTC3) - J43-4 (GND)*1

Y - W-B

Quick heater assembly operation signal
  • Engine running
  • Combination switch assembly (ECO mode switch) off
  • Temperature setting: MAX HOT
  • Ambient temperature: -10°C (14°F) or lower
  • Engine coolant temperature: 65°C (149°F) or lower
  • Light control switch off
  • Blower switch: On

Below 1 V
  • Engine running
  • Combination switch assembly (ECO mode switch) off
  • Temperature setting: MAX HOT
  • Ambient temperature: -10°C (14°F) or lower
  • Engine coolant temperature: 65°C (149°F) or lower
  • Light control switch off
  • Blower switch: Off

11 to 14 V

J42-13 (TAM) - J42-2 (SG-2)

G - B

Cooler (ambient temp. sensor) thermistor signal
  • Engine switch on (IG)
  • Ambient temperature: 25°C (77°F)

1.35 to 1.75 V
  • Engine switch on (IG)
  • Ambient temperature: 40°C (104°F)

0.9 to 1.2 V

J42-14 (TR) - J42-1 (SG-1)

P - L

Cooler (room temp. sensor) thermistor signal
  • Engine switch on (IG)
  • Cabin temperature: 25°C (77°F)

1.8 to 2.2 V
  • Engine switch on (IG)
  • Cabin temperature: 40°C (104°F)

1.2 to 1.6 V

J42-20 (ECOS) - J43-4 (GND)

V - W-B

Combination switch assembly (ECO mode switch) signal
  • Engine switch on (IG)
  • Combination switch assembly (ECO mode switch) off

11 to 14 V
  • Engine switch on (IG)
  • Combination switch assembly (ECO mode switch) on

Below 1 V

J42-21 (LOCK) - J42-2 (SG-2)

B - B

A/C lock sensor signal
  • Engine running
  • Blower switch: LO
  • A/C switch: On

Pulse generation (See waveform 1)

J42-24 (PRE) - J42-3 (SG-4)

L - BE

Air conditioner pressure sensor signal
  • Engine running
  • Air conditioning system operating
  • Refrigerant pressure: Abnormal pressure (more than 2812 kPa (28.7 kgf/cm2, 408 psi))

4.61 V or higher
  • Engine running
  • Air conditioning system operating
  • Refrigerant pressure: Abnormal pressure (less than 196 kPa (2.0 kgf/cm2, 28 psi) or less)

Below 0.74 V
  • Engine running
  • Air conditioning system operating
  • Refrigerant pressure: Normal pressure (less than 2812 kPa (28.7 kgf/cm2, 408 psi) and more than 196 kPa (2.0 kgf/cm2, 28 psi))

0.74 to 4.61 V

J42-25 (DGS) - J42-2 (SG-2)*2

LG - B

Smog ventilation sensor signal (HC, CO)

28 seconds after engine switch turned on (IG) and sensor exposed to exhaust gas (HC, CO)

1.0 to 4.5 V

J42-27 (DGS1) - J42-2 (SG-2)*2

GR - B

Smog ventilation sensor signal (NOx)

120 seconds after engine switch turned on (IG) and sensor exposed to exhaust gas (NOx)

1.0 to 4.5 V

J43-1 (B) - J43-4 (GND)

R - W-B

Power source (Back-up)

Always

11 to 14 V

J43-2 (IG+) - J43-4 (GND)

GR - W-B

Power source (IG)

Engine switch on (IG)

11 to 14 V

Engine switch off

Below 1 V

J43-3 (SOL+) - J43-4 (GND)

SB - W-B

Compressor solenoid operation signal
  • Engine running
  • Blower switch: LO
  • A/C switch: On

Pulse generation

(See waveform 2)

J43-4 (GND) - Body ground

W-B - Body ground

Ground for main power supply

Always

Below 1 V

J43-6 (BLW) - J43-4 (GND)

L - W-B

Blower motor speed control signal
  • Engine switch on (IG)
  • Blower switch: LO

Pulse generation

(See waveform 3)

J43-11 (CANH) - J43-12 (CANL)

LG - W

CAN communication system

CAN communication is performed

Pulse generation

J43-18 (PTC1) - J43-4 (GND)*1

LG - W-B

Quick heater assembly operation signal
  • Engine running
  • Combination switch assembly (ECO mode switch) off
  • Temperature setting: MAX HOT
  • Ambient temperature: 10°C (50°F) or lower
  • Engine coolant temperature: 75°C (167°F) or lower
  • Light control switch off
  • Blower switch: On

Below 1 V
  • Engine running
  • Combination switch assembly (ECO mode switch) off
  • Temperature setting: MAX HOT
  • Ambient temperature: 10°C (50°F) or lower
  • Engine coolant temperature: 75°C (167°F) or lower
  • Light control switch off
  • Blower switch: Off

11 to 14 V

z3-2 (BUS G) - Body ground

-

Ground for BUS IC

Always

Below 1 V

z3-3 (BUS) - z3-2 (BUS G)

-

BUS IC control signal

Engine switch on (IG)

Pulse generation

z3-4 (B BUS) - z3-2 (BUS G)

-

Power supply for BUS IC

Always

11 to 14 V

z3-5 (SGA) - Body ground

-

Ground for No. 1 cooler thermistor

Always

Below 1 V

z3-6 (TEA) - z3-5 (SGA)

-

No. 1 cooler thermistor signal
  • Engine switch on (IG)
  • Evaporator temperature: 0°C (32°F)

2.0 to 2.4 V
  • Engine switch on (IG)
  • Evaporator temperature: 15°C (59°F)

1.4 to 1.8 V
  • *1: w/ PTC Heater
  • *2: w/ Smog Ventilation Sensor

(a) Waveform 1:

Item

Content

Terminal No.

J42-21 (LOCK) - J42-2 (SG-2)

Tool Setting

200 mV/DIV., 10 ms./DIV.

Vehicle Condition
  • Engine running
  • Blower switch: LO
  • A/C switch: On

(b) Waveform 2:

Item

Content

Terminal No.

J43-3 (SOL+) - J43-4 (GND)

Tool Setting

5 V/DIV., 500 μs./DIV.

Vehicle Condition
  • Engine running
  • Blower switch: LO
  • A/C switch: On

(c) Waveform 3:

Item

Content

Terminal No.

J43-6 (BLW) - J43-4 (GND)

Tool Setting

2 V/DIV., 1 ms./DIV.

Vehicle Condition
  • Engine switch on (IG)
  • Blower switch: LO

AIR CONDITIONING AMPLIFIER ASSEMBLY (w/ Rear Air Conditioning System)

HINT:

Check from the rear of the connector while it is connected to the air conditioning amplifier assembly.

Terminal No.

(Symbol)

Wiring Color

Terminal Description

Condition

Specified Condition

J42-1 (SG-1) - Body ground

L - Body ground

Ground for cooler (room temp. sensor) thermistor

Always

Below 1 V

J42-2 (SG-2) - Body ground

B - Body ground

Ground for cooler (ambient temp. sensor) thermistor, A/C lock sensor, smog ventilation sensor*2

Always

Below 1 V

J42-3 (SG-4) - Body ground

BE - Body ground

Ground for air conditioner pressure sensor

Always

Below 1 V

J42-6 (S5-3) - J42-2 (SG-2)

W - B

Power supply for air conditioner pressure sensor

Engine switch on (IG)

4.75 to 5.25 V

Engine switch off

Below 1 V

J42-9 (MGC) - J43-4 (GND)

R - W-B

Magnetic clutch operation signal
  • Engine running
  • Blower switch: LO
  • A/C switch: Off

11 to 14 V
  • Engine running
  • Blower switch: LO
  • A/C switch: On

Below 1 V

J42-10 (PTC2) - J43-4 (GND)*1

G - W-B

Quick heater assembly operation signal
  • Engine running
  • Combination switch assembly (ECO mode switch) off
  • Temperature setting: MAX HOT
  • Ambient temperature: 0°C (32°F) or lower
  • Engine coolant temperature: 70°C (158°F) or lower
  • Light control switch off
  • Blower switch: On

Below 1 V
  • Engine running
  • Combination switch assembly (ECO mode switch) off
  • Temperature setting: MAX HOT
  • Ambient temperature: 0°C (32°F) or lower
  • Engine coolant temperature: 70°C (158°F) or lower
  • Light control switch off
  • Blower switch: Off

11 to 14 V

J42-11 (PTC3) - J43-4 (GND)*1

Y - W-B

Quick heater assembly operation signal
  • Engine running
  • Combination switch assembly (ECO mode switch) off
  • Temperature setting: MAX HOT
  • Ambient temperature: -10°C (14°F) or lower
  • Engine coolant temperature: 65°C (149°F) or lower
  • Light control switch off
  • Blower switch: On

Below 1 V
  • Engine running
  • Combination switch assembly (ECO mode switch) off
  • Temperature setting: MAX HOT
  • Ambient temperature: -10°C (14°F) or lower
  • Engine coolant temperature: 65°C (149°F) or lower
  • Light control switch off
  • Blower switch: Off

11 to 14 V

J42-13 (TAM) - J42-2 (SG-2)

G - B

Cooler (ambient temp. sensor) thermistor signal
  • Engine switch on (IG)
  • Ambient temperature: 25°C (77°F)

1.35 to 1.75 V
  • Engine switch on (IG)
  • Ambient temperature: 40°C (104°F)

0.9 to 1.2 V

J42-14 (TR) - J42-1 (SG-1)

P - L

Cooler (room temp. sensor) thermistor signal
  • Engine switch on (IG)
  • Cabin temperature: 25°C (77°F)

1.8 to 2.2 V
  • Engine switch on (IG)
  • Cabin temperature: 40°C (104°F)

1.2 to 1.6 V

J42-20 (ECOS) - J43-4 (GND)

V - W-B

Combination switch assembly (ECO mode switch) signal
  • Engine switch on (IG)
  • Combination switch assembly (ECO mode switch) off

11 to 14 V
  • Engine switch on (IG)
  • Combination switch assembly (ECO mode switch) on

Below 1 V

J42-21 (LOCK) - J42-2 (SG-2)

B - B

A/C lock sensor signal
  • Engine running
  • Blower switch: LO
  • A/C switch: On

Pulse generation (See waveform 1)

J42-24 (PRE) - J42-3 (SG-4)

L - BE

Air conditioner pressure sensor signal
  • Engine running
  • Air conditioning system operating
  • Refrigerant pressure: Abnormal pressure (more than 2812 kPa (28.7 kgf/cm2, 408 psi))

4.61 V or higher
  • Engine running
  • Air conditioning system operating
  • Refrigerant pressure: Abnormal pressure (less than 196 kPa (2.0 kgf/cm2, 28 psi) or less)

Below 0.74 V
  • Engine running
  • Air conditioning system operating
  • Refrigerant pressure: Normal pressure (less than 2812 kPa (28.7 kgf/cm2, 408 psi) and more than 196 kPa (2.0 kgf/cm2, 28 psi))

0.74 to 4.61 V

J42-25 (DGS) - J42-2 (SG-2)*2

LG - B

Smog ventilation sensor signal (HC, CO)

28 seconds after engine switch turned on (IG) and sensor exposed to exhaust gas (HC, CO)

1.0 to 4.5 V

J42-27 (DGS1) - J42-2 (SG-2)*2

GR - B

Smog ventilation sensor signal (NOx)

120 seconds after engine switch turned on (IG) and sensor exposed to exhaust gas (NOx)

1.0 to 4.5 V

J43-1 (B) - J43-4 (GND)

R - W-B

Power source (Back-up)

Always

11 to 14 V

J43-2 (IG+) - J43-4 (GND)

GR - W-B

Power source (IG)

Engine switch on (IG)

11 to 14 V

Engine switch off

Below 1 V

J43-3 (SOL+) - J43-4 (GND)

SB - W-B

Compressor solenoid operation signal
  • Engine running
  • Blower switch: LO
  • A/C switch: On

Pulse generation

(See waveform 2)

J43-4 (GND) - Body ground

W-B - Body ground

Ground for main power supply

Always

Below 1 V

J43-6 (BLW) - J43-4 (GND)

L - W-B

Blower motor speed control signal
  • Engine switch on (IG)
  • Blower switch: LO

Pulse generation

(See waveform 3)

J43-11 (CANH) - J43-12 (CANL)

LG - W

CAN communication system

CAN communication is performed

Pulse generation

J43-16 (LIN3) - J43-4 (GND)

W - W-B

LIN communication signal

Engine switch on (IG)

Pulse generation

J43-18 (PTC1) - J43-4 (GND)*1

LG - W-B

Quick heater assembly operation signal
  • Engine running
  • Combination switch assembly (ECO mode switch) off
  • Temperature setting: MAX HOT
  • Ambient temperature: 10°C (50°F) or lower
  • Engine coolant temperature: 75°C (167°F) or lower
  • Light control switch off
  • Blower switch: On

Below 1 V
  • Engine running
  • Combination switch assembly (ECO mode switch) off
  • Temperature setting: MAX HOT
  • Ambient temperature: 10°C (50°F) or lower
  • Engine coolant temperature: 75°C (167°F) or lower
  • Light control switch off
  • Blower switch: Off

11 to 14 V

J48-1 (GND2) - Body ground

W-B - Body ground

Ground for rear power supply

Always

Below 1 V

J48-2 (RBUG) - Body ground

GR - Body ground

Ground for BUS IC (for Rear side)

Always

Below 1 V

J48-3 (RBBU) - Body ground

LG - Body ground

Power supply for BUS IC (for Rear side)

Always

11 to 14 V

J48-4 (+B2) - Body ground

L - Body ground

Rear power source (Back-up)

Always

11 to 14 V

J48-6 (TR) - J48-20 (SG-7)

R - G

Cooler (No. 2 room temp. sensor) thermistor signal
  • Engine switch on (IG)
  • Rear cabin temperature: 25°C (77°F)

1.8 to 2.2 V
  • Engine switch on (IG)
  • Rear cabin temperature: 40°C (104°F)

1.2 to 1.6 V

J48-8 (TEC) - J48-21 (SG-8)

R - V

Rear evaporator temperature sensor signal
  • Engine switch on (IG)
  • Rear evaporator temperature: 0°C (32°F)

2.0 to 2.4 V
  • Engine switch on (IG)
  • Rear evaporator temperature: 15°C (59°F)

1.4 to 1.8 V

J48-12 (BLWH) - Body ground

V - Body ground

Rear blower motor speed control signal
  • Engine switch on (IG)
  • Rear blower switch: LO

Pulse generation

(See waveform 4)

J48-20 (SG-7) - Body ground

G - Body ground

Ground for cooler (No. 2 room temp. sensor) thermistor

Always

Below 1 V

J48-21 (SG-8) - Body ground

V - Body ground

Ground for rear evaporator temperature sensor

Always

Below 1 V

J48-22 (RBUS) - J48-2 (RBUG)

SB - GR

BUS IC control signal (for Rear side)

Engine switch on (IG)

Pulse generation

z3-2 (BUS G) - Body ground

-

Ground for BUS IC (for Front side)

Always

Below 1 V

z3-3 (BUS) - z3-2 (BUS G)

-

BUS IC control signal (for Front side)

Engine switch on (IG)

Pulse generation

z3-4 (B BUS) - z3-2 (BUS G)

-

Power supply for BUS IC (for Front side)

Always

11 to 14 V

z3-5 (SGA) - Body ground

-

Ground for No. 1 cooler thermistor

Always

Below 1 V

z3-6 (TEA) - z3-5 (SGA)

-

No. 1 cooler thermistor signal
  • Engine switch on (IG)
  • Evaporator temperature: 0°C (32°F)

2.0 to 2.4 V
  • Engine switch on (IG)
  • Evaporator temperature: 15°C (59°F)

1.4 to 1.8 V
  • *1: w/ PTC Heater
  • *2: w/ Smog Ventilation Sensor

(a) Waveform 1:

Item

Content

Terminal No.

J42-21 (LOCK) - J42-2 (SG-2)

Tool Setting

200 mV/DIV., 10 ms./DIV.

Vehicle Condition
  • Engine running
  • Blower switch: LO
  • A/C switch: On

(b) Waveform 2:

Item

Content

Terminal No.

J43-3 (SOL+) - J43-4 (GND)

Tool Setting

5 V/DIV., 500 μs./DIV.

Vehicle Condition
  • Engine running
  • Blower switch: LO
  • A/C switch: On

(c) Waveform 3:

Item

Content

Terminal No.

J43-6 (BLW) - J43-4 (GND)

Tool Setting

2 V/DIV., 1 ms./DIV.

Vehicle Condition
  • Engine switch on (IG)
  • Blower switch: LO

(d) Waveform 4:

Item

Content

Terminal No.

J48-12 (BLWH) - Body ground

Tool Setting

2 V/DIV., 500 μs./DIV.

Vehicle Condition
  • Engine switch on (IG)
  • Rear blower switch: LO

NO. 2 AIR CONDITIONING CONTROL ASSEMBLY (w/ Rear Air Conditioning System)

HINT:

Check from the rear of the connector while it is connected to the No. 2 air conditioning control assembly.

Terminal No.

(Symbol)

Wiring Color

Terminal Description

Condition

Specified Condition

S90-2 (IG) - S90-4 (E)

LG - W-B

Power source (IG)

Engine switch on (IG)

11 to 14 V

Engine switch off

Below 1 V

S90-4 (E) - Body ground

W-B - Body ground

Ground for No. 2 air conditioning control assembly

Always

Below 1 V

S90-6 (BLIN) - S90-4 (E)

G - W-B

LIN communication signal

Engine switch on (IG)

Pulse generation

RADIO RECEIVER ASSEMBLY (A/C CONTROL PANEL)

w/ Navigation System: Click here

w/ Audio and Visual System (for 12.3 Inch Display): Click here

w/ Audio and Visual System (for 8 Inch Display): Click here

MULTI-DISPLAY ASSEMBLY

w/ Navigation System: Click here

w/ Audio and Visual System (for 12.3 Inch Display): Click here

w/ Audio and Visual System (for 8 Inch Display): Click here

    Diagnosis System
    DIAGNOSIS SYSTEM DESCRIPTION Air conditioning system data and Diagnostic Trouble Codes (DTCs) can be read through the Data Link Connector 3 (DLC3) of the vehicle. When the system seems to be malfuncti ...

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    CHECK MODE PROCEDURE REFRIGERANT SHORTAGE CHECK IN NORMAL OPERATION (CHECK A/C SWITCH INDICATOR AND DTC) (a) Start the engine. (b) Check that the A/C switch indicator remains on when the following con ...

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