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

  1. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY

    • *: w/ PTC Heater

    U124081E02

    1. Disconnect the H118 air conditioning amplifier connector.

    2. 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

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

    3. Reconnect the H118 air conditioning amplifier connectors.

    4. 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

      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

      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

      • 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

      • 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

      • 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

      • 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

      • 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

      Ignition switch ON

      Blower switch LO

      Below 1 V
    5. E106664E35

      Using an oscilloscope, check waveform 1.

      Table 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

  2. CHECK MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

    E187733E01

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

    2. 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.

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

    4. 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

      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.