AIR CONDITIONING SYSTEM PTC Heater Circuit

DESCRIPTION

The air conditioning amplifier assembly sends operation signals to the PTC heater relays when quick heater assembly operation conditions are met. Based on the signals from the air conditioning amplifier assembly, the PTC heater relays turn on, and power is supplied to the quick heater assembly installed in the air conditioning radiator assembly.

Quick Heater Assembly Operation Condition
Control ECU Condition
Air Conditioning Amplifier Assembly Power switch on (READY)
Combination switch assembly (ECO mode switch) off
Blower switch: on
Temperature settings: MAX HOT
IDH terminal signal less than 1 V (Inverter with converter assembly overload not detected)

  • Engine coolant temperature 60°C (140°F) or lower (2 PTC heater relays operating)

  • Engine coolant temperature 64°C (147°F) or lower (1 PTC heater relay operating)
Ambient temperature 10°C (50°F) or lower

WIRING DIAGRAM

B004EINE14

CAUTION / NOTICE / HINT

Note


  • If the auxiliary battery voltage is low, the PTC heater may not operate. When "Operation of Electrical Items Restricted." is displayed on the multi-information display in the combination meter assembly, inspect the auxiliary battery, referring to On-vehicle Inspection for the charging system.

    Click here

  • If the auxiliary battery voltage is low, the PTC heater may not operate. When "Operation of Electrical Items Restricted." is not displayed on the multi-information display in the combination meter assembly, check the Data List item "Battery Control Count (Body ECU)".

    Click here

  • Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE


  1. PERFORM ACTIVE TEST USING GTS


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Body Electrical / Air Conditioner / Active Test.

    5. Perform the Active Test according to the display on the GTS.


      Body Electrical > Air Conditioner > Active Test
      Tester Display Measurement Item Control Range Diagnostic Note
      Heater Active Level Quick heater assembly Min.: 0, Max.: 2 -

      Body Electrical > Air Conditioner > Active Test
      Tester Display
      Heater Active Level
      OK
      Heater Active Level changes normally.
      Result
      Proceed to
      OK
      NG

    NG

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    OK

  2. INSPECT PTC HEATER RELAY


    1. Remove the PTC heater relays.

    2. B004GOJC08
      *a

      Component without harness connected

      (PTC Heater Relay)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3 - 5 Auxiliary battery voltage not applied between terminals 1 and 2 10 kΩ or higher
      3 - 5 Auxiliary battery voltage applied between terminals 1 and 2 Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE PTC HEATER RELAY Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - POWER SOURCE)


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

      Standard Voltage
      PTC HTR NO. 1
      Tester Connection Condition Specified Condition
      Relay terminal 5 - Body ground Power switch off 11 to 14 V
      Relay terminal 1 - Body ground Power switch off Below 1 V
      Relay terminal 1 - Body ground Power switch on (IG) 11 to 14 V
      Standard Voltage
      PTC HTR NO. 2
      Tester Connection Condition Specified Condition
      Relay terminal 5 - Body ground Power switch off 11 to 14 V
      Relay terminal 1 - Body ground Power switch off Below 1 V
      Relay terminal 1 - Body ground Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - AIR CONDITIONING AMPLIFIER ASSEMBLY)


    1. Disconnect the O9 air conditioning amplifier assembly connector.

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

      Standard Resistance
      PTC HTR NO. 1
      Tester Connection Condition Specified Condition
      Relay terminal 2 - O9-8 (PTC1) Always Below 1 Ω
      Relay terminal 2 or O9-8 (PTC1) - Body ground Always 10 kΩ or higher
      Standard Resistance
      PTC HTR NO. 2
      Tester Connection Condition Specified Condition
      Relay terminal 2 - O9-26 (PTC2) Always Below 1 Ω
      Relay terminal 2 or O9-26 (PTC2) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - QUICK HEATER ASSEMBLY AND BODY GROUND)


    1. Disconnect the O12 and O13 quick heater assembly connectors.

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

      Standard Resistance
      PTC HTR NO. 1
      Tester Connection Condition Specified Condition
      Relay terminal 3 - O12-2 (B) Always Below 1 Ω
      O12-1 (E) - Body ground Always Below 1 Ω
      O12-2 (B) or Relay terminal 3 - Body ground Always 10 kΩ or higher
      Standard Resistance
      PTC HTR NO. 2
      Tester Connection Condition Specified Condition
      Relay terminal 3 - O13-2 (B) Always Below 1 Ω
      O13-1 (E) - Body ground Always Below 1 Ω
      O13-2 (B) or Relay terminal 3 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. INSPECT QUICK HEATER ASSEMBLY


    1. Remove the quick heater assembly.

      Click here

    2. B004G0LC04
      *a

      Component without harness connected

      (Quick Heater Assembly)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      O12-1 (E) - O12-2 (B) Always Below 1 Ω
      O13-1 (E) - O13-2 (B) Always Below 1 Ω
      O12-1 (E) - O13-1 (E) Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    NG

    REPLACE QUICK HEATER ASSEMBLY Click here