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

  1. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY

    U123622E04

    1. Disconnect the H46 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

      H46-1 (IG+) - H46-14 (GND)

      Y - W-B

      Ignition power supply

      Ignition switch ON

      11 to 14 V

      Ignition switch off

      Below 1 V

      H46-21 (B) - H46-14 (GND)

      W - W-B

      Battery power source

      Always

      11 to 14 V

      H46-14 (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.

    3. Reconnect the H46 air conditioning amplifier connector.

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

      Terminal No. (Symbol)

      Wiring Color

      Terminal Description

      Condition

      Specified Condition

      z19-2 (BUS G) - Body ground

      -

      Ground for BUS IC

      Always

      Below 1 Ω

      H46-22 (BLW) - H46-14 (GND)

      R - W-B

      Blower motor control signal

      • Ignition switch ON

      • Blower switch LO

      Pulse generation

      (see waveform 1)

      H46-10 (S5-3) - H46-13 (SG-2)

      B - G

      Power supply for air conditioning pressure sensor

      Ignition switch ON

      4.75 to 5.25 V

      H46-9 (PRE) - H46-13 (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

      H46-30 (S5-1) - H46-14 (GND)

      LG - W-B

      Cooler thermistor (solar sensor) power source

      Ignition switch ON

      4.5 to 5.5 V

      H46-33 (TSD) - H46-14 (GND)

      L - W-B

      Cooler thermistor (solar sensor) power signal (for driver side)

      • Ignition switch ON

      • Solar sensor subjected to electric light

      • Vehicle indoors

      0.8 to 4.3 V

      • Ignition switch ON

      • Solar sensor covered with cloth

      • Vehicle indoors

      Below 0.8 V

      H46-32 (TSP) - H46-14 (GND)

      P - W-B

      Cooler thermistor (solar sensor) power signal (for front passenger side)

      • Ignition switch ON

      • Solar sensor subjected to electric light

      • Vehicle indoors

      0.8 to 4.3 V

      • Ignition switch ON

      • Solar sensor covered with cloth

      • Vehicle indoors

      Below 0.8 V

      H46-29 (TR) - H46-34 (SG-1)

      GR - V

      Room temperature sensor signal

      • Ignition switch ON

      • Cabin temperature at 25°C (77°F)

      1.8 to 2.2 V

      • Ignition switch ON

      • Cabin temperature at 40°C (104°F)

      1.2 to 1.6 V

      H46-2 (SOL+) - H46-14 (GND)

      LG - W-B

      Compressor with pulley assembly operation signal

      • Engine running

      • A/C switch on

      • Blower switch LO

      Pulse generation

      (see waveform 2)

      H46-40 (PTC1) - Body ground*1

      W - Body ground

      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 off → on (after 30 seconds)

      11 to 14 V → Below 1 V*2

      H46-3 (PTC2) - Body ground*1

      B - Body ground

      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 off → on (after 30 seconds)

      11 to 14 V → Below 1 V*2

      H46-39 (PTC3) - Body ground*1

      BR - Body ground

      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 off → on (after 30 seconds)

      11 to 14 V → Below 1 V*2

      H46-27 (HLS)*1 - H46-14 (GND)

      BE - W-B

      Headlight signal (PTC heater control)

      • Engine started

      • Headlight dimmer switch off

      11 to 14 V

      • Engine started

      • Headlight dimmer switch on

      Below 1 V

      z19-5 (SGA) - Body ground

      -

      Ground for evaporator temperature sensor

      Always

      Below 1 Ω

      z19-6 (TEA) - z19-5 (SGA)

      -

      Evaporator temperature sensor signal

      • Ignition switch ON

      • Evaporator temperature at 0°C (32°F)

      1.7 to 2.1 V

      • Ignition switch ON

      • Evaporator temperature at 15°C (59°F)

      0.9 to 1.3 V

      z19-3 (BUS) - z19-2 (BUS G)

      -

      BUS IC control signal

      Ignition switch ON

      Pulse generation

      z19-4 (B BUS) - z19-2 (BUS G)

      -

      Power supply for BUS IC

      Always

      11 to 14 V

      • *1: w/ PTC Heater

      Tip:

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

      • If the result is not as specified, the air conditioning amplifier assembly may have a malfunction.

    5. E103396E12

      Using an oscilloscope, check waveform 1.

      Table 1. Blower Motor Control Signal

      Item

      Content

      Terminal No. (Symbol)

      H46-22 (BLW) - H46-14 (GND)

      Tool Setting

      1 V/DIV., 500 μs/DIV.

      Condition

      • Ignition switch ON

      • Blower switch LO
      Tip:

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

    6. E106664E10

      Using an oscilloscope, check waveform 2.

      Table 2. Compressor with Pulley Operation Signal

      Item

      Content

      Terminal No. (Symbol)

      H46-2 (SOL+) - H46-14 (GND)

      Tool Setting

      5 V/DIV., 500 μs/DIV.

      Condition

      • Engine running

      • A/C switch on

      • Blower switch LO

  2. CHECK AIR CONDITIONING CONTROL ASSEMBLY

    U122505E05

    1. Disconnect the H21 control connector.

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

      Terminal No. (Symbol)

      Wiring Color

      Terminal Description

      Condition

      Specified Condition

      H21-2 (IG+) - H21-5 (GND)

      R - BR

      Ignition power supply

      Ignition switch ON

      11 to 14 V

      Ignition switch off

      Below 1 V

      H21-5 (GND) - Body ground

      BR - Body ground

      Ground

      Always

      Below 1 Ω

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

  3. 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.