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


  1. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY

    A002N3BE04

    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

      Tech Tips

      *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. A002NP2E12

      Using an oscilloscope, check waveform 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

      Tech Tips

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

    6. A002LL5E10

      Using an oscilloscope, check waveform 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

    A002N2DE05

    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)

    A002QN3E01

    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.