AIR CONDITIONING SYSTEM(for Manual Air Conditioning System) TERMINALS OF ECU

CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY

*: w/ PTC Heater

Disconnect the H118 air conditioning amplifier connector.

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

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
H118-1 (IG+) - H118-23 (GND)	Y - W-B	Ignition power supply	Ignition switch ON	11 to 14 V
Ignition switch off	Below 1 V
H118-23 (GND) - Body ground	W-B - Body ground	Ground for main power supply	Always	Below 1 Ω

Terminal No.

(Symbol)

Wiring Color

Terminal Description

Condition

Specified Condition

H118-1 (IG+) - H118-23 (GND)

Y - W-B

Ignition power supply

Ignition switch ON

11 to 14 V

Ignition switch off

Below 1 V

H118-23 (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.

Reconnect the H118 air conditioning amplifier connectors.

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

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
H118-24 (S5-3) - H118-5 (SG-2)	B - G	Power supply for air conditioning pressure sensor	Ignition switch ON A/C switch off	4.75 to 5.25 V
H118-24 (S5-3) - H118-5 (SG-2)	B - G	Power supply for air conditioning pressure sensor	Ignition switch off	Below 1 V
H118-7 (PRE) - H118-5 (SG-2)	L - G	Air conditioning pressure sensor signal	Ignition switch ON Refrigerant pressure normal (less than 3.025 MPa [30.9 kgf/cm², 438.6 psi] and more than 0.176 MPa [1.8 kgf/cm², 25.5 psi])	0.70 to 4.69 V
			Ignition switch ON Refrigerant pressure abnormal (less than 0.176 MPa [1.8 kgf/cm², 25.5 psi])	Below 0.70 V
			Ignition switch ON Refrigerant pressure abnormal (more than 3.025 MPa [30.9 kgf/cm², 438.6 psi])	4.69 V or higher
H118-11 (SOL+) - H118-23 (GND)	LG - W-B	Compressor with pulley assembly operation signal	Engine running A/C switch on Blower switch LO	Pulse generation (See waveform 1)
H118-17 (SBLW) - H118-23 (GND)	BE - W-B	Blower motor speed control signal	Ignition switch ON Blower switch off	11 to 14 V
H118-17 (SBLW) - H118-23 (GND)	BE - W-B	Blower motor speed control signal	Ignition switch ON Blower switch LO	Below 1 V
H118-4 (TE) - H118-15 (SG-3)	W - P	Evaporator temperature sensor signal	Ignition switch ON Evaporator temperature at 0°C (32°F)	1.7 to 2.0 V
H118-4 (TE) - H118-15 (SG-3)	W - P	Evaporator temperature sensor signal	Ignition switch ON Evaporator temperature at 15°C (59°F)	1.0 to 1.3 V
H118-15 (SG-3) - Body ground	P - Body ground	Ground for evaporator temperature sensor	Always	Below 1 V
H118-2 (A/C) - H118-23 (GND)	V - W-B	A/C switch signal	Ignition switch ON A/C switch off	Below 1 V
H118-2 (A/C) - H118-23 (GND)	V - W-B	A/C switch signal	Ignition switch ON A/C switch on	11 to 14 V
H118-16 (LED) - H118-23 (GND)	GR - W-B	A/C switch indicator light signal	Ignition switch ON A/C switch off Blower switch on	11 to 14 V
H118-16 (LED) - H118-23 (GND)	GR - W-B	A/C switch indicator light signal	Ignition switch ON A/C switch on Blower switch on	Below 4 V
H118-13 (PTC1)* - H118-23 (GND)	W - W-B	HTR SUB 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 75°C (167°F) or less Headlight dimmer switch off Blower switch on	Below 1 V
H118-19 (PTC2)* - H118-23 (GND)	B - W-B	HTR SUB 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 70°C (158°F) or less Headlight dimmer switch off Blower switch on	Below 1 V
H118-20 (PTC3)* - H118-23 (GND)	BR - W-B	HTR SUB 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 65°C (149°F) or less Headlight dimmer switch off Blower switch on	Below 1 V
H118-3 (HEAT)* - H118-23 (GND)	LG - W-B	MAX HOT switch signal	Ignition switch ON MAX HOT switch off	Below 1 V
H118-3 (HEAT)* - H118-23 (GND)	LG - W-B	MAX HOT switch signal	Ignition switch ON MAX HOT switch on	11 to 14 V
H118-21 (HLS)* - H118-23 (GND)	BE - W-B	Headlight signal (PTC Heater control)	Engine started Headlight switch off	11 to 14 V
H118-21 (HLS)* - H118-23 (GND)	BE - W-B	Headlight signal (PTC Heater control)	Engine started Headlight switch on	Below 1 V
H118-14 (HR) - H118-23 (GND)	G - W-B	Heater main relay operation signal	Ignition switch ON Blower switch off	11 to 14 V
H118-14 (HR) - H118-23 (GND)	G - W-B	Heater main relay operation signal	Ignition switch ON Blower switch LO	Below 1 V

Using an oscilloscope, check waveform 1.

Compressor with Pulley Operation Signal
Item	Content
Terminal No. (Symbol)	H118-11 (SOL+) - H118-23 (GND)
Tool Setting	5 V/DIV., 500 μs/DIV.
Vehicle Condition	Engine running A/C switch on Blower switch LO

CHECK MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

Disconnect the DB, DE, DG and H80 ECU connectors.

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

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
DE-28 (GND1) - Body ground	W-B - Body ground	Ground	Always	Below 1 Ω
H80-4 (GND2) - Body ground	W-B - Body ground	Ground	Always	Below 1 Ω
DB-30 (BECU) - Body ground	W - Body ground	Power source	Always	11 to 14 V
DG-1 (ALTB) - Body ground	W - Body ground	Power source	Always	11 to 14 V

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

Reconnect the DB, DE, DG, and H80 ECU connectors.

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

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
H79-20 (HRLY) - DE-28 (GND1)*	B - W-B	H-LP relay drive output	Headlight dimmer switch in head position	Below 1 V
H79-20 (HRLY) - DE-28 (GND1)*	B - W-B	H-LP relay drive output	Headlight dimmer switch not in head position	11 to 14 V

*: w/ PTC Heater

If the result is not as specified, the main body ECU (instrument panel junction block assembly) may have a malfunction.