Toyota 4Runner: PTC Heater Circuit

Toyota 4Runner Service Manual / Vehicle Interior / Heating / Air Conditioning / Air Conditioning System(for Manual 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

PROCEDURE

1.	INSPECT PTC HEATER RELAY (PTC NO. 1, PTC NO. 2, PTC NO. 3)

(a) Remove the PTC NO. 1 relay from the engine room No. 1 relay block, junction block.

(b) Remove the PTC NO. 2 and PTC NO. 3 relays from the engine room No. 2 relay block.

Standard Resistance:

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

REPLACE PTC HEATER RELAY (PTC NO. 1, PTC NO. 2, PTC NO. 3)

2.	CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY

(a) Remove the air conditioning amplifier assembly with its connectors still connected (See page ).

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
F42-3 (PTC1) - Body ground	Engine running (1250 rpm or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 79°C (174°F) or less Headlight dimmer switch off Blower switch off	Below 1 V*
F42-22 (PTC2) - Body ground	Engine running (1250 rpm or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 76°C (169°F) or less Headlight dimmer switch off Blower switch off
F42-4 (PTC3) - Body ground	Engine running (1250 rpm or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 73°C (163°F) or less Headlight dimmer switch off Blower switch off
F42-3 (PTC1) - Body ground	Engine running (1250 rpm or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 79°C (174°F) or less Headlight dimmer switch off Blower switch on	11 to 14 V*
F42-22 (PTC2) - Body ground	Engine running (1250 rpm or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 76°C (169°F) or less Headlight dimmer switch off Blower switch on
F42-4 (PTC3) - Body ground	Engine running (1250 rpm or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 73°C (163°F) or less Headlight dimmer switch off Blower switch on

Text in Illustration

*a	Component with harness connected (Air Conditioning Amplifier Assembly)

HINT:

*: After the measurement conditions are met, wait 30 seconds before performing measurements.

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

3.	CHECK HARNESS AND CONNECTOR (ENGINE ROOM NO. 1 RELAY BLOCK, JUNCTION BLOCK - AIR CONDITIONING AMPLIFIER)

(a) Remove the PTC NO. 1 relay from the engine room No. 1 relay block, junction block.

(b) Disconnect the F42 amplifier connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
PTC NO. 1 relay terminal 1 - F42-3 (PTC1)	Always	Below 1 Ω
PTC NO. 1 relay terminal 1 - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.	CHECK HARNESS AND CONNECTOR (ENGINE ROOM NO. 2 RELAY BLOCK - AIR CONDITIONING AMPLIFIER)

(a) Remove the PTC NO. 2 and PTC NO. 3 relays from the engine room No. 2 relay block.

(b) Disconnect the F42 amplifier connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
PTC NO. 2 relay terminal 1 - F42-22 (PTC2)	Always	Below 1 Ω
PTC NO. 3 relay terminal 1 - F42-4 (PTC3)	Always	Below 1 Ω
PTC NO. 2 relay terminal 1 - Body ground	Always	10 kΩ or higher
PTC NO. 3 relay terminal 1 - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

5.	CHECK HARNESS AND CONNECTOR (ENGINE ROOM NO. 1 RELAY BLOCK, JUNCTION BLOCK - QUICK HEATER)

(a) Remove the PTC NO. 1 relay from the engine room No. 1 relay block, junction block.

(b) Disconnect the F85 heater connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
PTC NO. 1 relay terminal 3 - F85-2 (B)	Always	Below 1 Ω
PTC NO. 1 relay terminal 3 - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

6.	CHECK HARNESS AND CONNECTOR (ENGINE ROOM NO. 2 RELAY BLOCK - QUICK HEATER)

(a) Remove the PTC NO. 2 and PTC NO. 3 relays from the engine room No. 2 relay block.

(b) Disconnect the F85 heater connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
PTC NO. 2 relay terminal 3 - F85-3 (B)	Always	Below 1 Ω
PTC NO. 3 relay terminal 3 - F85-1 (B)	Always	Below 1 Ω
PTC NO. 2 relay terminal 3 - Body ground	Always	10 kΩ or higher
PTC NO. 3 relay terminal 3 - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

7.	CHECK HARNESS AND CONNECTOR (ENGINE ROOM NO. 1 RELAY BLOCK, JUNCTION BLOCK - BATTERY AND BODY GROUND)

(a) Remove the PTC NO. 1 relay from the engine room No. 1 relay block, junction block.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
PTC NO. 1 relay terminal 5 - Body ground	Always	11 to 14 V

Standard Resistance:

Tester Connection	Condition	Specified Condition
PTC NO. 1 relay terminal 2 - Body ground	Always	Below 1 Ω

Text in Illustration

PTC NO. 1 Relay

Component without relay installed

(Engine Room No. 1 Relay Block, Junction Block)

REPAIR OR REPLACE HARNESS OR CONNECTOR

8.	CHECK HARNESS AND CONNECTOR (ENGINE ROOM NO. 2 RELAY BLOCK - BATTERY AND BODY GROUND)

(a) Remove the PTC NO. 2 and PTC NO. 3 relays from the engine room No. 2 relay block.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
PTC NO. 2 relay terminal 5 - Body ground	Always	11 to 14 V
PTC NO. 3 relay terminal 5 - Body ground	Always	11 to 14 V

Standard Resistance:

Tester Connection	Condition	Specified Condition
PTC NO. 2 relay terminal 2 - Body ground	Always	Below 1 Ω
PTC NO. 3 relay terminal 2 - Body ground	Always	Below 1 Ω

Text in Illustration

PTC NO. 2 Relay

PTC NO. 3 Relay

Component without relay installed

(Engine Room No. 2 Relay Block)

REPAIR OR REPLACE HARNESS OR CONNECTOR

9.	INSPECT QUICK HEATER ASSEMBLY

(a) Remove the quick heater assembly (See page ).

(b) 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)

REPLACE QUICK HEATER ASSEMBLY

10.	CHECK HARNESS AND CONNECTOR (QUICK HEATER - BODY GROUND)

(a) Disconnect the F86 heater connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
F86-1 (E) - Body ground	Always	Below 1 Ω
F86-2 (E) - Body ground	Always	Below 1 Ω

Text in Illustration

*a	Front view of wire harness connector (to Quick Heater Assembly)

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

REPAIR OR REPLACE HARNESS OR CONNECTOR

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