Heater Control Switch Circuit: Procedure

1. Measure the resistance.
   1. Remove the No. 3 heater control.
   2. Disconnect the connector from the No. 3 heater control.
      Fig 1: Inspecting No. 3 Heater Control E20 Connector Terminals

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection	Switch Condition	Specified Condition
      E20-2 (B) - E20-3 (A/C)	A/C switch: LOCK	Below 1 Ω
      E20-2 (B) - E20-3 (A/C)	A/C switch: FREE	10 kΩ or higher
      E20-7 (B) - E20-8 (E)*1	Air mix control dial: MAX HOT position	Below 1 Ω
      E20-7 (B) - E20-8 (E)*1	Air mix control dial: except MAX HOT position	10 kΩ or higher

      • *1: w/ PTC Heater Assembly
2. Check that the indicator light comes on.
   1. Connect a positive (+) lead from the battery to terminal 3 and a negative (-) lead from the battery to terminal 4, and check that the indicator light comes on.

      OK

      The indicator light comes on.

3. Check that the illumination comes on.
   1. Connect a positive (+) lead from the battery to terminal 5 and a negative (-) lead from the battery to terminal 6, and check that the illumination comes on.

      OK

      The illumination comes on.

      TEXT IN ILLUSTRATION
      
      

      *A	w/ PTC Heater Assembly
      *a	Component without harness connected (No. 3 Heater Control)

NG → See step   4 

OK: Go to next step 

1. Measure the voltage according to the value(s) in the table below.
   Fig 2: Checking Harness And E20 Connector (No. 3 Heater Control - Battery)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   E20-2 (B) - Body ground	Ignition switch: ON	11 to 14 V
   E20-2 (B) - Body ground	Ignition switch: OFF	Below 1 V
   E20-7 (B) - Body ground*1	Ignition switch: ON	11 to 14 V
   E20-7 (B) - Body ground*1	Ignition switch: OFF	Below 1 V

   • *1: w/ PTC heater Assembly
   TEXT IN ILLUSTRATION
   
   

   *A	w/ PTC Heater Assembly
   *a	Front view of wire harness connector (to No. 3 Heater Control)

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the connector from the A/C amplifier.
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   E20-3 (A/C) - E8-15 (A/C)*2	Always	Below 1 Ω
   E20-4 (AIND) - E8-16 (LED)*2	Always	Below 1 Ω
   E20-3 (A/C) - E73-27 (A/C)*3	Always	Below 1 Ω
   E20-4 (AIND) - E73-28 (LED)*3	Always	Below 1 Ω
   E20-8 (E) - E9-14 (HEAT)*1	Always	Below 1 Ω
   E20-3 (A/C) - Body ground	Always	10 kΩ or higher
   E20-4 (AIND) - Body ground	Always	10 kΩ or higher
   E20-8 (E) - Body ground*1	Always	10 kΩ or higher

   • *1: w/ PTC heater Assembly
   • *2: for 2AZ-FE
   • *3: for 2ZR-FE

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   5