GSIC - Global Service Information Center

# AIR CONDITIONING SYSTEM > TERMINALS OF ECU

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CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY (w/o PTC HEATER)

1. Disconnect the A9 A/C amplifier connector.

2. Measure the voltage and resistance of the wire harness side connector.

   Symbols (Terminal No.) | Wiring Color | Terminal Description | Condition | Specified Condition
   IG+ (A9-10) - GND (A9-18) | R-L - L | Power source (IG) | Ignition switch OFF | Below 1 V
   IG+ (A9-10) - GND (A9-18) | R-L - L | Power source (IG) | Ignition switch ON | 10 to 14 V
   GND (A9-18) - Body ground | L - Body ground | Ground | Always | Below 1 Ω
   ACON (A9-4) - GND (A9-18) | R-G - L | A/C switch signal | A/C switch OFF | Below 1 V
   ACON (A9-4) - GND (A9-18) | R-G - L | A/C switch signal | A/C switch ON | 10 to 14 V
   IND- (A9-13) - GND (A9-18) | R-L - L | A/C indicator light signal | A/C switch OFF | Below 1 V
   IND- (A9-13) - GND (A9-18) | R-L - L | A/C indicator light signal | A/C switch ON | 10 to 14 V

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

3. Reconnect the A9 connector.

4. Measure the voltage and resistance of the connector.

   Symbols (Terminal No.) | Wiring Color | Terminal Description | Condition | Specified Condition
   PSW (A9-3) - GND (A9-18) | Y-B - L | A/C pressure switch signal | Ignition switch START, refrigerant pressure normal, A/C switch ON, blower switch ON | 10 to 14 V
   PSW (A9-3) - GND (A9-18) | Y-B - L | A/C pressure switch signal | Ignition switch START, refrigerant pressure less than 0.196 MPa (2.0 kgf/cm2, 28 psi) or more than 3.14 MPa (32.0 kgf/cm2, 455 psi), A/C switch ON, blower switch ON | Below 1 V
   TEfin (A9-7) - SG-1 (A9-18) | G - P | A/C evaporator temperature sensor signal | Ignition switch ON, evaporator temperature is 0°C (32°F), temperature control knob: MAX COOL | 2.0 to 2.4 V
   TEfin (A9-7) - SG-1 (A9-18) | G - P | A/C evaporator temperature sensor signal | Ignition switch ON, evaporator temperature is 15°C (59°F), temperature control knob: MAX COOL | 1.4 to 1.8 V
   SG-1 (A9-8) - Body ground | P - L | Ground for A/C evaporator temperature sensor | Always | Below 1 Ω
   MGC (A9-1) - GND (A9-18) | L-W - L | Magnet clutch signal | Ignition switch START, magnet clutch is not engaged | Below 1 V
   MGC (A9-1) - GND (A9-18) | L-W - L | Magnet clutch signal | Ignition switch START, magnet clutch is engaged | 10 to 14 V
   ACT (A9-2) - GND (A9-18) | R-L - L | Magnet on permit signal | Ignition switch START, A/C switch OFF, blower switch ON | Below 1 V
   ACT (A9-2) - GND (A9-18) | R-L - L | Magnet on permit signal | Ignition switch START, A/C switch ON, blower switch ON | 10 to 14 V
   AC1 (A9-14) - GND (A9-18) | Y - L | Idle-up request signal | Ignition switch START, magnet clutch is not engaged | 10 to 14 V
   AC1 (A9-14) - GND (A9-18) | Y - L | Idle-up request signal | Ignition switch START, magnet clutch is engaged | Below 1 V

   1. If the result is not as specified, the A/C amplifier may have a malfunction.

CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY (w/ PTC HEATER)

1. Disconnect the A9 A/C amplifier connector.

2. Measure the voltage and resistance of the wire harness side connector.

   Symbols (Terminal No.) | Wiring Color | Terminal Description | Condition | Specified Condition
   IG (A9-20) - GND (A9-29) | R-L - L | Power source (IG) | Ignition switch OFF | Below 1V
   IG (A9-20) - GND (A9-29) | R-L - L | Power source (IG) | Ignition switch ON | 10 to 14 V
   GND (A9-29) - Body ground | L - Body ground | Ground | Always | Below 1 Ω
   ACON (A9-8) - GND (A9-29) | R-G - L | A/C switch signal | A/C switch OFF | Below 1 V
   ACON (A9-8) - GND (A9-29) | R-G - L | A/C switch signal | A/C switch ON | 10 to 14 V
   IND- (A9-9) - GND (A9-29) | R-L - L | A/C indicator light signal | A/C switch OFF | Below 1 V
   IND- (A9-9) - GND (A9-29) | R-L - L | A/C indicator light signal | A/C switch ON | 10 to 14 V
   BLW (MHOT) (A9-38) - GND (A9-29) | R-L - L | Max. HOT switch signal | Ignition switch ON, temperature control knob: Max. HOT | Below 1 Ω
   BLW (MHOT) (A9-38) - GND (A9-29) | R-L - L | Max. HOT switch signal | Ignition switch ON, temperature control knob: except Max. HOT | 10 kΩ or higher
   POWHTR (A9-5) - GND (A9-29) | L-O - L | Heater switch signal | Heater switch ON | Below 1 Ω
   POWHTR (A9-5) - GND (A9-29) | L-O - L | Heater switch signal | Heater switch OFF | 10 kΩ or higher
   MGC (A9-19) - GND (A9-29) | B - L | Magnet clutch relay signal | Ignition switch ON | 10 to 14 V
   MGC (A9-19) - GND (A9-29) | B - L | Magnet clutch relay signal | Ignition switch OFF | Below 1 V
   TAIL (A9-7) - GND (A9-29) | G - L | Light control switch signal | Light control switch ON | 10 to 14 V
   TAIL (A9-7) - GND (A9-29) | G - L | Light control switch signal | Light control switch OFF | Below 1 V

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

3. Reconnect the A9 connector.

4. Measure the voltage and resistance of the connector.

   Symbols (Terminal No.) | Wiring Color | Terminal Description | Condition | Specified Condition
   PSW (A9-4) - GND (A9-29) | Y-B - L | A/C pressure switch signal | Ignition switch START, refrigerant pressure normal, A/C switch ON, blower switch ON | 10 to 14 V
   PSW (A9-4) - GND (A9-29) | Y-B - L | A/C pressure switch signal | Ignition switch START, refrigerant pressure less than 0.196 MPa (2.0 kgf/cm2, 28 psi) or more than 3.14 MPa (32.0 kgf/cm2, 455 psi), A/C switch ON, blower switch ON | Below 1 V
   TE (A9-24) - SG-1 (A9-31) | G - P | A/C evaporator temperature sensor signal | Ignition switch ON, evaporator temperature is 0°C (32°F), temperature control knob: MAX COOL | 2.0 to 2.4 V
   TE (A9-24) - SG-1 (A9-31) | G - P | A/C evaporator temperature sensor signal | Ignition switch ON, evaporator temperature is 15°C (59°F), temperature control knob: MAX COOL | 1.4 to 1.8 V
   SG-1 (A9-31) - Body ground | P - L | Ground for A/C evaporator temperature sensor | Always | Below 1 Ω
   MGC (A9-19) - GND (A9-29) | B - L | Magnet clutch signal | Ignition switch START, magnet clutch is not engaged | Below 1 V
   MGC (A9-19) - GND (A9-29) | B - L | Magnet clutch signal | Ignition switch START, magnet clutch is engaged | 10 to 14 V
   ACT (A9-39) - GND (A9-29) | R-L - L | Magnet on permit signal | Ignition switch START, A/C switch OFF, blower switch ON | Below 1 V
   ACT (A9-39) - GND (A9-29) | R-L - L | Magnet on permit signal | Ignition switch START, A/C switch ON, blower switch ON | 10 to 14 V
   AC1 (A9-35) - GND (A9-29) | Y - L | Idle-up request signal | Ignition switch START, magnet clutch is not engaged | 10 to 14 V
   AC1 (A9-35) - GND (A9-29) | Y - L | Idle-up request signal | Ignition switch START, magnet clutch is engaged | Below 1.0 V
   BLW (MHOT) (A9-38) - GND (A9-29) | R-L - L | Max. HOT switch signal | Ignition switch ON, temperature control knob: Max. HOT | 10 to 14 V
   BLW (MHOT) (A9-38) - GND (A9-29) | R-L - L | Max. HOT switch signal | Ignition switch ON, temperature control knob: except Max. HOT | Below 1 V
   POWHTR (A9-5) - GND (A9-29) | L-O - L | Heater switch input signal | Heater switch ON | Below 1 V
   POWHTR (A9-5) - GND (A9-29) | L-O - L | Heater switch input signal | Heater switch OFF | 10 to 14 V
   SWIN (HOTLP) (A9-15) - GND (A9-29) | P - L | Heater switch indicator light signal | Heater switch ON | Below 1 V
   SWIN (HOTLP) (A9-15) - GND (A9-29) | P - L | Heater switch indicator light signal | Heater switch OFF | 10 to 14 V
   RPTC (A9-26) - GND (A9-29) | L-W - L | Heater switch output signal | Heater switch ON | 10 to 14 V
   RPTC (A9-26) - GND (A9-29) | L-W - L | Heater switch output signal | Heater switch OFF | Below 1 V
   TW (A9-32) - GND (A9-29) | P - L | Water temperature signal | Ignition switch ON | Pulse generation
   TACO (A9-33) - GND (A9-29) | B-W - L | Tachometer signal | Engine running | Pulse generation (see waveform 1)
   ALT (A9-37) - GND (A9-29) | G - L | Generator | Ignition switch ON | 9 to 14 V
   PTC1 (A9-3) - GND (A9-29) | R-W - L | PTC heater relay signal | Heater switch ON, temperature control knob: Max. HOT, coolant temperature: 55°C (131°F) or lower, blower switch LO | Below 1 V
   PTC1 (A9-3) - GND (A9-29) | R-W - L | PTC heater relay signal | Heater switch ON, temperature control knob: Max. HOT, coolant temperature: 55°C (131°F) or lower, blower switch OFF | 10 to 14 V
   PTC2 (A9-2) - GND (A9-29) | GR - L | PTC heater relay signal | Heater switch ON, temperature control knob: Max. HOT, coolant temperature: 55°C (131°F) or lower, blower switch LO | Below 1 V
   PTC2 (A9-2) - GND (A9-29) | GR - L | PTC heater relay signal | Heater switch ON, temperature control knob: Max. HOT, coolant temperature: 55°C (131°F) or lower, blower switch OFF | 10 to 14 V

   1. If the result is not as specified, the A/C amplifier may have a malfunction.

5. Inspect using an oscilloscope.

   1. Waveform 1 (Reference)

      Item | Content
      Symbols (Terminal No.) | TACO (A9-33) - GND (A9-29)
      Tool Setting | 5 V/DIV., 20 msec./DIV.
      Condition | Engine idling

      HINT:
        As engine speed increases, the wavelength shortens.

CHECK ECM

1. Measure the voltage of the connectors.

   1. 1TR-FE, 2TR-FE

      Symbols (Terminal No.) | Wiring Color | Terminal Description | Condition | Specified Condition
      ACT (E10-25) - E01 (E12-7) | R-L - W-B | Magnet on permit signal | Ignition switch START, A/C switch OFF | Below 1 V
      ACT (E10-25) - E01 (E12-7) | R-L - W-B | Magnet on permit signal | Ignition switch START, A/C switch ON | 10 to 14 V
      AC1 (E10-24) - E01 (E12-7) | Y - W-B | Idle-up request signal | Ignition switch START, A/C magnet clutch is engaged | Below 1.0 V
      AC1 (E10-24) - E01 (E12-7) | Y - W-B | Magnet on permit signal | Ignition switch START, A/C magnet clutch is not engaged | 10 to 14 V

      1. If the result is not as specified, the ECM may have a malfunction.

   2. 2KD-FTV

      Symbols (Terminal No.) | Wiring Color | Terminal Description | Condition | Specified Condition
      ACT (E6-19) - E01 (E8-7) | R-L - W-B | Magnet on permit signal | Ignition switch START, A/C switch OFF | Below 1 V
      ACT (E6-19) - E01 (E8-7) | R-L - W-B | Magnet on permit signal | Ignition switch START, A/C switch ON | 10 to 14 V
      AC1 (E6-18) - E01 (E8-7) | Y - W-B | Idle-up request signal | Ignition switch START, magnet clutch is engaged | Below 1 V
      AC1 (E6-18) - E01 (E8-7) | Y - W-B | Magnet on permit signal | Ignition switch START, magnet clutch is not engaged | 10 to 14 V
      THWO (E5-2) - E01 (E8-7)* | P - W-B | Water temperature signal | Ignition switch ON | Pulse generation
      HSW (E6-20) - E01 (E8-7)* | L-W - W-B | Heater switch output signal for idle-up | Heater switch ON | Below 1 V
      HSW (E6-20) - E01(E8-7)* | L-W - W-B | Heater switch output signal for idle-up | Heater switch OFF | 10 to 14 V
      TACH (E5-4) - E01 (E8-7)* | B-W - W-B | Tachometer signal | Engine running | Pulse generation (see waveform 1)

      1. If the result is not as specified, the ECM may have a malfunction.

         HINT:
           *: w/ PTC Heater

2. Inspect using an oscilloscope (w/ PTC heater only).

   1. Waveform 1 (Reference)

      Item | Content
      Symbols (Terminal No.) | TACH (E5-4) - E01 (E8-7)
      Tool Setting | 5 V/DIV., 20 msec./DIV.
      Condition | Engine idling

      HINT:
        As engine speed increases, the wavelength shortens.