- PTC heater (quick heater assembly) malfunction
- Air conditioning amplifier assembly malfunction
- Harness and connector
- PTC heater relays
| Last Modified: 07-31-2024 | 6.11:8.1.0 | Doc ID: RM1000000025TYS |
| Model Year Start: 2023 | Model: Corolla | Prod Date Range: [09/2022 - ] |
| Title: HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM (for HV Model): PTC Heater Circuit; 2023 - 2025 MY Corolla Corolla HV [09/2022 - ] | ||
|
PTC Heater Circuit |
DESCRIPTION
The air conditioning amplifier assembly sends operation signals to the PTC heater relays when PTC heater (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 PTC heater (quick heater assembly) installed in the air conditioning radiator assembly.
HINT:
- When all drive conditions are fulfilled, 3 heater elements are driven.
- The number of heater elements driven varies depending on the engine coolant temperature.
If the heating performance is poor when it is cold, the following factors may be the cause.
|
Malfunction Status |
Factor |
|---|---|
|
Heating performance is poor when it is cold |
|
WIRING DIAGRAM
CAUTION / NOTICE / HINT
NOTICE:
Inspect the fuses for circuits related to this system before performing the following procedure.
PROCEDURE
|
1. |
CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY |
(a) Disconnect the I49 and I48 air conditioning amplifier assembly connectors.
|
*a |
Front view of wire harness connector (to Air Conditioning Amplifier Assembly) |
- |
- |
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection |
Switch Condition |
Specified Condition |
|---|---|---|
|
I49-23 (PTC1) - Body ground |
Ignition switch off → ON |
Below 1 V → 11 to 14 V |
|
I48-16 (PTC2) - Body ground |
Ignition switch off → ON |
Below 1 V → 11 to 14 V |
|
I48-17 (PTC3) - Body ground |
Ignition switch off → ON |
Below 1 V → 11 to 14 V |
| NG |
|
|
|
2. |
CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY |
(a) Connect the I49 and I48 air conditioning amplifier assembly connectors.
|
*a |
Component with harness connected (Air Conditioning Amplifier Assembly) |
- |
- |
(b) Perform the Active Test according to the display on the GTS.
Body Electrical > Air Conditioner > Active Test
|
Tester Display |
Measurement Item |
Control Range |
Diagnostic Note |
|---|---|---|---|
|
PTC Heater |
This test activates the PTC Heater. (PTC heater (quick heater assembly)) |
0: Min. 3: Max. |
Operate with the ignition switch ON (READY) and the vehicle stopped. |
Body Electrical > Air Conditioner > Active Test
|
Tester Display |
|---|
|
PTC Heater |
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
I49-23 (PTC1) - Body ground |
|
11 to 14 V → Below 1 V |
|
I48-16 (PTC2) - Body ground |
|
11 to 14 V → Below 1 V |
|
I48-17 (PTC3) - Body ground |
|
11 to 14 V → Below 1 V |
| NG |
|
REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY
|
|
|
3. |
CHECK PTC HEATER (QUICK HEATER ASSEMBLY) |
(a) Disconnect the J2 and J1 PTC heater (quick heater assembly) connectors.
|
*a |
Front view of wire harness connector (to PTC Heater (Quick Heater Assembly)) |
- |
- |
(b) Perform the Active Test according to the display on the GTS.
Body Electrical > Air Conditioner > Active Test
|
Tester Display |
Measurement Item |
Control Range |
Diagnostic Note |
|---|---|---|---|
|
PTC Heater |
This test activates the PTC Heater. (PTC heater (quick heater assembly)) |
0: Min. 3: Max. |
Operate with the ignition switch ON (READY) and the vehicle stopped. |
Body Electrical > Air Conditioner > Active Test
|
Tester Display |
|---|
|
PTC Heater |
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
J1-3 - Body ground |
|
Below 1 V → 11 to 14 V |
|
J1-1 - Body ground |
|
Below 1 V → 11 to 14 V |
|
J2-2 - Body ground |
|
Below 1 V → 11 to 14 V |
| NG |
|
|
|
4. |
CHECK HARNESS AND CONNECTOR (PTC HEATER (QUICK HEATER ASSEMBLY) - BODY GROUND) |
(a) Disconnect the J2 and J1 PTC heater (quick heater assembly) connectors.
|
*a |
Front view of wire harness connector (to PTC Heater (Quick Heater Assembly)) |
- |
- |
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
J2-1 - Body ground |
Always |
Below 1 Ω |
|
J1-2 - Body ground |
Always |
Below 1 Ω |
| OK |
|
REPLACE PTC HEATER (QUICK HEATER ASSEMBLY)
|
| NG |
|
REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
5. |
INSPECT PTC HEATER RELAY (PTC HTR NO. 1, PTC HTR NO. 2 and PTC HTR NO. 3) |
Click here
![2020 - 2025 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - ]; HEATING / AIR CONDITIONING: RELAY: ON-VEHICLE INSPECTION](/t3Portal/stylegraphics/info.gif)
| NG |
|
REPLACE PTC HEATER RELAY (PTC HTR NO. 1, PTC HTR NO. 2 and PTC HTR NO. 3) |
|
|
6. |
CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - POWER SOURCE) |
(a) Remove the PTC heater relays (PTC HTR NO. 1, PTC HTR NO. 2 and PTC HTR NO. 3) from the No. 2 relay block assembly.
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
PTC HTR NO. 1 Relay
|
Tester Connection |
Switch Condition |
Specified Condition |
|---|---|---|
|
Relay terminal 3 - Body ground |
Always |
11 to 14 V |
PTC HTR NO. 2 Relay
|
Tester Connection |
Switch Condition |
Specified Condition |
|---|---|---|
|
Relay terminal 3 - Body ground |
Always |
11 to 14 V |
PTC HTR NO. 3 Relay
|
Tester Connection |
Switch Condition |
Specified Condition |
|---|---|---|
|
Relay terminal 3 - Body ground |
Always |
11 to 14 V |
| NG |
|
REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
7. |
CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - PTC HEATER (QUICK HEATER ASSEMBLY)) |
(a) Remove the PTC heater relays (PTC HTR NO. 1, PTC HTR NO. 2 and PTC HTR NO. 3) from the No. 2 relay block assembly.
(b) Disconnect the J2 and J1 PTC heater (quick heater assembly) connectors.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
PTC HTR NO. 1 Relay
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
Relay terminal 5 - J1-3 |
Always |
Below 1 Ω |
|
Relay terminal 5 or J1-3 - Other terminals and body ground |
Always |
10 kΩ or higher |
PTC HTR NO. 2 Relay
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
Relay terminal 5 - J1-1 |
Always |
Below 1 Ω |
|
Relay terminal 5 or J1-1 - Other terminals and body ground |
Always |
10 kΩ or higher |
PTC HTR NO. 3 Relay
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
Relay terminal 5 - J2-2 |
Always |
Below 1 Ω |
|
Relay terminal 5 or J2-2 - Other terminals and body ground |
Always |
10 kΩ or higher |
| OK |
|
REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY
|
| NG |
|
REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
8. |
INSPECT PTC HEATER RELAY (PTC HTR NO. 1, PTC HTR NO. 2 and PTC HTR NO. 3) |
Click here
| NG |
|
REPLACE PTC HEATER RELAY (PTC HTR NO. 1, PTC HTR NO. 2 and PTC HTR NO. 3) |
|
|
9. |
CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - POWER SOURCE) |
(a) Remove the PTC heater relays (PTC HTR NO. 1, PTC HTR NO. 2 and PTC HTR NO. 3) from the No. 2 relay block assembly.
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
PTC HTR NO. 1 Relay
|
Tester Connection |
Switch Condition |
Specified Condition |
|---|---|---|
|
Relay terminal 2 - Body ground |
Ignition switch off |
Below 1 V |
|
Ignition switch ON |
11 to 14 V |
PTC HTR NO. 2 Relay
|
Tester Connection |
Switch Condition |
Specified Condition |
|---|---|---|
|
Relay terminal 1 - Body ground |
Ignition switch off |
Below 1 V |
|
Ignition switch ON |
11 to 14 V |
PTC HTR NO. 3 Relay
|
Tester Connection |
Switch Condition |
Specified Condition |
|---|---|---|
|
Relay terminal 1 - Body ground |
Ignition switch off |
Below 1 V |
|
Ignition switch ON |
11 to 14 V |
| NG |
|
REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
10. |
CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - AIR CONDITIONING AMPLIFIER ASSEMBLY) |
(a) Remove the PTC heater relays (PTC HTR NO. 1, PTC HTR NO. 2 and PTC HTR NO. 3) from the No. 2 relay block assembly.
(b) Disconnect the I49 and I48 air conditioning amplifier assembly connectors.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
PTC HTR NO. 1 Relay
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
Relay terminal 1 - I49-23 (PTC1) |
Always |
Below 1 Ω |
|
Relay terminal 1 or I49-23 (PTC1) - Other terminals and body ground |
Always |
10 kΩ or higher |
PTC HTR NO. 2 Relay
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
Relay terminal 2 - I48-16 (PTC2) |
Always |
Below 1 Ω |
|
Relay terminal 2 or I48-16 (PTC2) - Other terminals and body ground |
Always |
10 kΩ or higher |
PTC HTR NO. 3 Relay
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
Relay terminal 2 - I48-17 (PTC3) |
Always |
Below 1 Ω |
|
Relay terminal 2 or I48-17 (PTC3) - Other terminals and body ground |
Always |
10 kΩ or higher |
| OK |
|
REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY
|
| NG |
|
REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|