| Last Modified: 05-13-2024 | 6.11:8.1.0 | Doc ID: RM100000002B6QM |
| Model Year Start: 2023 | Model: Corolla Hatchback | Prod Date Range: [03/2023 - ] |
| Title: M20A-FKS (ENGINE CONTROL): SFI SYSTEM: ECM Power Source Circuit; 2023 - 2025 MY Corolla Corolla Hatchback [03/2023 - ] | ||
|
ECM Power Source Circuit |
DESCRIPTION
When the ignition switch is turned to ON, the battery voltage is applied to the IGP terminal of the ECM. The output signal from the MREL terminal of the ECM causes current to flow to the coil of the EFI-MAIN NO. 1 relay, closing the contacts of the EFI-MAIN NO. 1 relay and supplying power to terminals +B and +B2 of the ECM.
WIRING DIAGRAM
CAUTION / NOTICE / HINT
NOTICE:
Inspect the fuses for circuits related to this system before performing the following procedure.
PROCEDURE
|
1. |
CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND) |
(a) Disconnect the ECM connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance (for K120):
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
A47-10 (E1) - Body ground |
Always |
Below 1 Ω |
Standard Resistance (for K121):
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
A178-22 (E1) - Body ground |
Always |
Below 1 Ω |
| NG |
|
REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
2. |
CHECK TERMINAL VOLTAGE (IGP TERMINAL VOLTAGE) |
(a) Disconnect the ECM connector.
(b) Turn the ignition switch to ON.
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage (for K120):
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
A47-2 (IGP) - Body ground |
Ignition switch ON |
11 to 14 V |
Standard Voltage (for K121):
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
A178-30 (IGP) - Body ground |
Ignition switch ON |
11 to 14 V |
for K120
|
*a |
Front view of wire harness connector (to ECM) |
for K121
|
*a |
Front view of wire harness connector (to ECM) |
| NG |
|
|
|
3. |
INSPECT EFI-MAIN NO. 1 RELAY |
Click here
![2023 - 2025 MY Corolla Corolla Hatchback [11/2022 - ]; M20A-FKS (ENGINE CONTROL): RELAY: ON-VEHICLE INSPECTION+](/t3Portal/stylegraphics/info.gif)
| NG |
|
REPLACE EFI-MAIN NO. 1 RELAY |
|
|
4. |
CHECK HARNESS AND CONNECTOR (EFI-MAIN NO. 1 RELAY - ECM) |
(a) Disconnect the ECM connector.
(b) Remove the EFI-MAIN NO. 1 relay, EFI-MAIN NO. 3 relay and EDU relay from the No. 1 engine room relay block and No. 1 junction block assembly.
HINT:
Remove the EFI-MAIN NO. 2 VVT, and EFI-MAIN NO. 3 relays connected between the checked terminals as the coil inside the relay influences the measurement value.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance (for K120):
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
1(EFI-MAIN NO.1 relay) - A47-15 (MREL) |
Always |
Below 1 Ω |
|
3(EFI-MAIN NO.1 relay) - A47-9 (+B) |
Always |
Below 1 Ω |
|
3(EFI-MAIN NO.1 relay) - A47-35 (+B2) |
Always |
Below 1 Ω |
|
1(EFI-MAIN NO.1 relay) or A47-15 (MREL) - Body ground and other terminals |
Always |
10 kΩ or higher |
|
3(EFI-MAIN NO.1 relay), A47-9(+B) or A47-35 (+B2) - Body ground and other terminals |
Always |
10 kΩ or higher |
Standard Resistance (for K121):
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
1(EFI-MAIN NO.1 relay) - A178-26 (MREL) |
Always |
Below 1 Ω |
|
3(EFI-MAIN NO.1 relay) - A178-21 (+B) |
Always |
Below 1 Ω |
|
3(EFI-MAIN NO.1 relay) - A178-51 (+B2) |
Always |
Below 1 Ω |
|
1(EFI-MAIN NO.1 relay) or A178-26 (MREL) - Body ground and other terminals |
Always |
10 kΩ or higher |
|
3(EFI-MAIN NO.1 relay), A178-21(+B) or A178-51 (+B2) - Body ground and other terminals |
Always |
10 kΩ or higher |
| NG |
|
REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
5. |
CHECK TERMINAL VOLTAGE (POWER SOURCE OF EFI-MAIN NO. 1 RELAY) |
|
*1 |
No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly |
|
*2 |
EFI-MAIN NO. 1 Relay |
(a) Remove the EFI-MAIN NO. 1 relay from the No. 1 engine room relay block and No. 1 junction block assembly.
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
2(EFI-MAIN NO. 1 relay) - Body ground |
Always |
11 to 14 V |
|
5(EFI-MAIN NO. 1 relay) - Body ground |
Always |
11 to 14 V |
| OK |
|
| NG |
|
REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - EFI-MAIN NO. 1 RELAY) |
|
6. |
INSPECT IGP-MAIN RELAY |
Click here
| NG |
|
REPLACE IGP-MAIN RELAY |
|
|
7. |
CHECK HARNESS AND CONNECTOR (IGP-MAIN RELAY - ECM) |
(a) Disconnect the ECM connector.
(b) Remove the IGP-MAIN relay from the No. 1 engine room relay block and No. 1 junction block assembly.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance (for K120):
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
3(IGP-MAIN relay) - A47-2 (IGP) |
Always |
Below 1 Ω |
|
3(IGP-MAIN relay) or A47-2 (IGP) - Body ground and other terminals |
Always |
10 kΩ or higher |
Standard Resistance (for K121):
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
3(IGP-MAIN relay) - A178-30 (IGP) |
Always |
Below 1 Ω |
|
3(IGP-MAIN relay) or A178-30 (IGP) - Body ground and other terminals |
Always |
10 kΩ or higher |
| NG |
|
REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
8. |
CHECK HARNESS AND CONNECTOR (POWER SOURCE VOLTAGE OF IGP-MAIN RELAY) |
|
*1 |
No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly |
|
*2 |
IGP-MAIN Relay |
(a) Remove the IGP-MAIN relay from the No. 1 engine room relay block and No. 1 junction block assembly.
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
5(IGP-MAIN relay) - Body ground |
Always |
11 to 14 V |
| NG |
|
REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - IGP-MAIN RELAY) |
|
|
9. |
CHECK HARNESS AND CONNECTOR (IGP-MAIN RELAY - BODY GROUND) |
(a) Remove the IGP-MAIN relay from the No. 1 engine room relay block and No. 1 junction block assembly.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
1(IGP-MAIN relay) - Body ground |
Always |
Below 1 Ω |
|
Result |
Proceed to |
|---|---|
|
OK (w/ Smart Key System) |
A |
|
OK (w/o Smart Key System) |
B |
|
NG |
C |
| B |
|
| C |
|
REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
10. |
CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - IGP-MAIN RELAY) |
(a) Disconnect the certification ECU (smart key ECU assembly) connector.
(b) Remove the IGP-MAIN relay from the No. 1 engine room relay block and No. 1 junction block assembly.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
O175-24 (IGPD) - 2(IGP-MAIN relay) |
Always |
Below 1 Ω |
|
O175-24 (IGPD) or 2(IGP-MAIN relay) - Body ground and other terminals |
Always |
10 kΩ or higher |
| OK |
|
| NG |
|
REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
11. |
INSPECT IGNITION OR STARTER SWITCH ASSEMBLY |
(a) Inspect the ignition or starter switch assembly.
Click here
| NG |
|
|
|
12. |
CHECK HARNESS AND CONNECTOR (IGNITION OR STARTER SWITCH ASSEMBLY - IGP-MAIN RELAY) |
(a) Disconnect the ignition or starter switch assembly connector.
(b) Remove the IGP-MAIN relay from the No. 1 engine room relay block and No. 1 junction block assembly.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
I12-8 (IG1) - 2 (IGP-MAIN relay) |
Always |
Below 1 Ω |
|
I12-8 (IG1) or 2 (IGP-MAIN relay) - Body ground and other terminals |
Always |
10 kΩ or higher |
| OK |
|
REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - IGNITION OR STARTER SWITCH ASSEMBLY) |
| NG |
|
REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|