Toyota CH-R Service Manual: 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

Engine running

ECO mode: Off

Blower switch: On

Temperature setting: MAX HOT

Light control switch off

  • Engine coolant temperature 65°C (149°F) or lower (3 PTC heater relays operating)
  • Engine coolant temperature 70°C (158°F) or lower (2 PTC heater relays operating)
  • Engine coolant temperature 75°C (167°F) or lower (1 PTC heater relay operating)
  • Ambient temperature -7°C (19°F) or lower (3 PTC heater relays operating)
  • Ambient temperature 16°C (61°F) or lower (2 PTC heater relays operating)
  • Ambient temperature 25°C (77°F) or lower (1 PTC heater relay operating)

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

PROCEDURE

1.

PERFORM ACTIVE TEST USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Air Conditioner / Active Test.

(e) Perform the Active Test according to the display on the Techstream.

Body Electrical > Air Conditioner > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Heater Active Level

Quick heater assembly

Min.: 0, Max.: 3

-

Body Electrical > Air Conditioner > Active Test

Tester Display

Heater Active Level

OK:

Heater Active Level changes normally.

NG

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

OK

2.

INSPECT PTC HEATER RELAY

(a) Remove the PTC heater relays.

(b) Inspect the PTC heater relays.

Click here

NG

REPLACE PTC HEATER RELAY

OK

3.

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

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

*1

NO. 2 ENGINE ROOM RELAY BLOCK

*2

PTC HTR NO. 1 Relay

*3

PTC HTR NO. 2 Relay

*4

PTC HTR NO. 3 Relay

Standard Voltage:

PTC HTR NO. 1

Tester Connection

Switch Condition

Specified Condition

Relay terminal 3 - Body ground

Ignition switch off

11 to 14 V

Relay terminal 1 - Body ground

Ignition switch off

Below 1 V

Relay terminal 1 - Body ground

Ignition switch on (IG)

11 to 14 V

Standard Voltage:

PTC HTR NO. 2

Tester Connection

Switch Condition

Specified Condition

Relay terminal 3 - Body ground

Ignition switch off

11 to 14 V

Relay terminal 1 - Body ground

Ignition switch off

Below 1 V

Relay terminal 1 - Body ground

Ignition switch on (IG)

11 to 14 V

Standard Voltage:

PTC HTR NO. 3

Tester Connection

Switch Condition

Specified Condition

Relay terminal 3 - Body ground

Ignition switch off

11 to 14 V

Relay terminal 1 - Body ground

Ignition switch off

Below 1 V

Relay terminal 1 - Body ground

Ignition switch on (IG)

11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.

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

(a) Disconnect the F138 and F139 air conditioning amplifier assembly connectors.

(b) 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 - F139-18 (PTC1)

Always

Below 1 Ω

Relay terminal 2 or F139-18 (PTC1) - Body ground

Always

10 kΩ or higher

Standard Resistance:

PTC HTR NO. 2

Tester Connection

Condition

Specified Condition

Relay terminal 2 - F138-10 (PTC2)

Always

Below 1 Ω

Relay terminal 2 or F138-10 (PTC2) - Body ground

Always

10 kΩ or higher

Standard Resistance:

PTC HTR NO. 3

Tester Connection

Condition

Specified Condition

Relay terminal 2 - F138-11 (PTC3)

Always

Below 1 Ω

Relay terminal 2 or F138-11 (PTC3) - Body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

5.

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

(a) Disconnect the H1 and H3 quick heater assembly connectors.

(b) 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 5 - H1-3 (B)

Always

Below 1 Ω

H1-2 (E) - Body ground

Always

Below 1 Ω

H3-1 (E) - Body ground

Always

Below 1 Ω

H1-3 (B) - Body ground

Always

10 kΩ or higher

Standard Resistance:

PTC HTR NO. 2

Tester Connection

Condition

Specified Condition

Relay terminal 5 - H1-1 (B)

Always

Below 1 Ω

H1-2 (E) - Body ground

Always

Below 1 Ω

H1-1 (B) - Body ground

Always

10 kΩ or higher

Standard Resistance:

PTC HTR NO. 3

Tester Connection

Condition

Specified Condition

Relay terminal 5 - H3-2 (B)

Always

Below 1 Ω

H3-1 (E) - Body ground

Always

Below 1 Ω

H3-2 (B) - Body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

6.

INSPECT QUICK HEATER ASSEMBLY

(a) Remove the quick heater assembly.

Click here

(b) Inspect the quick heater assembly.

Click here

OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

NG

REPLACE QUICK HEATER ASSEMBLY

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