PTC Heater Circuit: Procedure

1. Remove the PTC NO. 1, PTC NO. 2 and PTC NO. 3 fuses from the engine room No. 2 relay block.
2. Measure the resistance of the fuses.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   PTC NO. 1	Always	Below 1 Ω
   PTC NO. 2	Always	Below 1 Ω
   PTC NO. 3	Always	Below 1 Ω

NG → REPLACE FUSE 

OK: Go to next step 

1. Remove the PTC HTR1, PTC HTR2 and PTC HTR3 relays from the engine room No. 2 relay block.
   Fig 1: Identifying PTC Heater Relay

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance of the relays.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   3 - 5	When battery voltage is not applied to terminals 1 and 2)	10 kΩ or higher
   3 - 5	When battery voltage is applied to terminals 1 and 2)	Below 1 Ω

NG → REPLACE PTC HEATER RELAY 

OK: Go to next step 

1. Remove the PTC HTR1, PTC HTR2 and PTC HTR3 relays from the engine room No. 2 relay block.
   Fig 2: Identifying PTC HTR1, PTC HTR2 And PTC HTR3 Relays From The Engine Room No. 2 Relay Block

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

   Standard resistance

   Tester Connection	Condition	Specified Condition
   PTC HTR1 relay terminal 2 - Body ground	Always	Below 1 Ω
   PTC HTR2 relay terminal 2 - Body ground	Always	Below 1 Ω
   PTC HTR3 relay terminal 2 - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Remove the PTC HTR1, PTC HTR2 and PTC HTR3 relays from the engine room No. 2 relay block.
   Fig 3: Identifying PTC HTR1, PTC HTR2 And PTC HTR3 Relays From The Engine Room No. 2 Relay Block

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Turn the ignition switch on (IG).
3. When the PTC heater operating conditions are met (engine at idling speed or faster, ambient temperature is 10°C (50°F) or less, engine coolant temperature is 65°C (149°F) or less, set temperature switch is set to MAX HOT), turn the blower switch to the LO setting.
4. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Condition	Specified Condition
   PTC HTR1 relay terminal 1 - Body ground	Always	11 to 14 V
   PTC HTR2 relay terminal 1 - Body ground	Always	11 to 14 V
   PTC HTR3 relay terminal 1 - Body ground	Always	11 to 14 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Remove the PTC HTR1, PTC HTR2 and PTC HTR3 relays from the engine room No. 2 relay block.
   Fig 4: Identifying PTC HTR1, PTC HTR2 And PTC HTR3 Relays From The Engine Room No. 2 Relay Block

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

   Standard voltage

   Tester Connection	Condition	Specified Condition
   PTC HTR1 relay terminal 5 - Body ground	Always	11 to 14 V
   PTC HTR2 relay terminal 5 - Body ground	Always	11 to 14 V
   PTC HTR3 relay terminal 5 - Body ground	Always	11 to 14 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Remove the PTC HTR1, PTC HTR2 and PTC HTR3 relays from the engine room No. 2 relay block.
   Fig 5: Identifying PTC HTR1, PTC HTR2 And PTC HTR3 Relays From The Engine Room No. 2 Relay Block

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

   Standard resistance

   Tester Connection	Condition	Specified Condition
   PTC HTR1 relay terminal 3 - D44-2 (B)	Always	Below 1 Ω
   PTC HTR2 relay terminal 3 - D44-3 (B)	Always	Below 1 Ω
   PTC HTR3 relay terminal 3 - D44-1 (B)	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Remove the air conditioning amplifier. Refer to REMOVAL - Step 6 with its connectors still connected.
   Fig 6: Checking Air Conditioning Amplifier

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Turn the ignition switch on (IG).
3. When the PTC heater operating conditions are met (engine at idling speed or faster, ambient temperature is 10°C (50°F) or less, engine coolant temperature is 65°C (149°F) or less, set temperature switch is set to MAX HOT), turn the blower switch to the Lo setting.
4. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Condition	Specified Condition
   D37-3 (PTC1) - Body ground	Always	11 to 14 V
   D37-22 (PTC2) - Body ground	Always	11 to 14 V
   D37-4 (PTC3) - Body ground	Always	11 to 14 V

NG → See step   10 

OK: Go to next step 

1. Replace the PTC heater. Refer to DISASSEMBLY - Step 4 .

NEXT: Go to next step 

1. Operate the PTC heater to check that it functions properly.

   OK

   PTC heater function operates normally.

NG → See step   11 

OK → END (PTC HEATER IS DEFECTIVE)