AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System) PTC Heater Circuit

DESCRIPTION

PTC heater relays are closed in accordance with signals from the air conditioning amplifier assembly and power is supplied to the quick heater assembly installed on the radiator heater unit.

WIRING DIAGRAM

A01DY5XE01

INSPECTION PROCEDURE

Note

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

PROCEDURE


  1. INSPECT NO. 1 PTC HEATER RELAY AND NO. 2 PTC HEATER RELAY


    1. A01DWUNE03

      Remove the No. 1 PTC heater relay and No. 2 PTC heater relay Click here.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3 - 5 Battery voltage is not applied between terminals 1 and 2 10 kΩ or higher
      Battery voltage is applied between terminals 1 and 2 Below 1 Ω

    NG

    REPLACE NO. 1 PTC HEATER RELAY OR NO. 2 PTC HEATER RELAY Click here

    OK

  2. CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - AIR CONDITIONING AMPLIFIER AND BODY GROUND)


    1. Disconnect the P18 No. 1 PTC heater relay connector.

    2. Disconnect the P19 No. 2 PTC heater relay connector.

    3. Disconnect the A43 air conditioning amplifier assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      P18-1 - A43-1 (PTC1) Always Below 1 Ω
      P19-1 - A43-2 (PTC2)
      P18-1 - Body ground Always 10 kΩ or higher
      P19-1 - Body ground
      P18-2 - Body ground Always Below 1 Ω
      P19-2 - Body ground

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY


    1. A01DXBXE07
      Text in Illustration
      *a

      Component with harness connected

      (Air Conditioning Amplifier Assembly)

      Remove the air conditioning amplifier assembly with its connectors still connected Click here.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A43-1 (PTC1) - Body ground

      • Engine idling

      • Temperature switch MAX COLD to MAX HOT

      • Coolant temperature 65°C (149°F) or less

      • Ambient temperature 10°C (50°F) or less

      • Headlight dimmer switch not in head position

      • Generator is operating

      • Blower switch on (Lo level)

      • Heater switch assembly on

      		 11 to 14 V

      • Engine idling

      • Temperature switch MAX COLD to MAX HOT

      • Coolant temperature 65°C (149°F) or less

      • Ambient temperature 10°C (50°F) or less

      • Headlight dimmer switch not in head position

      • Generator is operating

      • Blower switch on (Lo level)

      • Heater switch assembly off

      		 Below 1 V
      A43-2 (PTC2) - Body ground

      • Engine idling

      • Temperature switch MAX COLD to MAX HOT

      • Coolant temperature 65°C (149°F) or less

      • Ambient temperature 10°C (50°F) or less

      • Headlight dimmer switch not in head position

      • Generator is operating

      • Blower switch on (Lo level)

      • Heater switch assembly on

      		 11 to 14 V

      • Engine idling

      • Temperature switch MAX COLD to MAX HOT

      • Coolant temperature 65°C (149°F) or less

      • Ambient temperature 10°C (50°F) or less

      • Headlight dimmer switch not in head position

      • Generator is operating

      • Blower switch on (Lo level)

      • Heater switch assembly off

      		 Below 1 V

    NG

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    OK

  4. CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - BATTERY)


    1. A01DWX7E01
      Text in Illustration
      *1 for No. 1 PTC Heater Relay
      *2 for No. 2 PTC Heater Relay
      *a

      Front view of wire harness connector

      (to No. 1 PTC Heater Relay or No. 2 PTC Heater Relay)

      Disconnect the P18 No. 1 PTC heater relay connector.

    2. Disconnect the P19 No. 2 PTC heater relay connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      P18-3 - Body ground Always 11 to 14 V
      P19-3 - Body ground

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Disconnect the P18 No. 1 PTC heater relay connector.

    2. Disconnect the P19 No. 2 PTC heater relay connector.

    3. Disconnect the P16 and P17 quick heater assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      P19-5 - P17-1 (B) Always Below 1 Ω
      P19-5 - P17-3 (B)
      P18-5 - P17-2 (B)
      P18-5 - Body ground Always 10 kΩ or higher
      P18-5 - Body ground
      P16-1 (E) - Body ground Always Below 1 Ω
      P16-2 (E) - Body ground

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. INSPECT QUICK HEATER ASSEMBLY


    1. A01E27ZE08

      Remove the quick heater assembly Click here.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1 (B) - 1 (E) Always Below 1 kΩ
      2 (B) - 1 (E)
      2 (B) - 2 (E)
      3 (B) - 2 (E)

    NG

    REPLACE QUICK HEATER ASSEMBLY Click here

    OK

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