Toyota Corolla Cross: ECM Power Source Circuit
DESCRIPTION
When the ignition switch is turned to ON, the auxiliary battery voltage is applied to the IGSW 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 TERMINAL VOLTAGE (POWER SOURCE OF EFI-MAIN NO. 1 RELAY) |
| (a) Remove the EFI-MAIN NO. 1 relay from the No. 1 engine room relay block assembly. |
|
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection | Condition |
Specified Condition |
|---|---|---|
|
5 (EFI-MAIN NO. 1 relay) - Body ground |
Always | 11 to 14 V |
|
2 (EFI-MAIN NO. 1 relay) - Body ground |
Always | 11 to 14 V |
| NG | .gif) | REPAIR OR REPLACE HARNESS OR CONNECTOR (AUXILIARY BATTERY - NO. 1 INTEGRATION RELAY) |
|
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| 2. |
INSPECT EFI-MAIN NO. 1 RELAY |
Click here
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| NG | |
REPLACE NO. 1 INTEGRATION RELAY |
|
| 3. |
CHECK HARNESS AND CONNECTOR (EFI-MAIN NO. 1 RELAY - ECM) |
(a) Disconnect the ECM connector.
(b) Remove the EFI-MAIN NO. 1 relay, D INJ relay, EFI-MAIN NO. 2 relay and EFI-MAIN NO. 3 relay from the No. 1 engine room relay block assembly.
HINT:
Remove the D INJ relay, EFI-MAIN NO. 2 relay and EFI-MAIN NO. 3 relay 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:
|
Tester Connection | Condition |
Specified Condition |
|---|---|---|
|
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) - A47-15 (MREL) |
Always | Below 1 Ω |
|
3 (EFI-MAIN NO. 1 relay) or A47-9 (+B) - Body ground and other terminals |
Always | 10 kΩ or higher |
|
3 (EFI-MAIN NO. 1 relay) or A47-35 (+B2) - Body ground and other terminals |
Always | 10 kΩ or higher |
|
1 (EFI-MAIN NO. 1 relay) or A47-15 (MREL) - Body ground and other terminals |
Always | 10 kΩ or higher |
HINT:
If a short is detected in any of the above circuits, there may be a malfunction in the circuit of a connected ECU.
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 4. |
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:
|
Tester Connection | Condition |
Specified Condition |
|---|---|---|
|
A47-10 (E1) - Body ground |
Always | Below 1 Ω |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 5. |
CHECK HARNESS AND CONNECTOR (IGP RELAY - BODY GROUND) |
(a) Remove the IGP relay from the No. 1 engine room relay block assembly.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection | Condition |
Specified Condition |
|---|---|---|
|
2 (IGP relay) - Body ground |
Always | Below 1 Ω |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 6. |
CHECK TERMINAL VOLTAGE (IGP TERMINAL VOLTAGE) |
|
*a | Front view of wire harness connector (to ECM) |
(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:
|
Tester Connection | Condition |
Specified Condition |
|---|---|---|
|
A47-2 (IGP) - Body ground |
Ignition switch ON | 11 to 14 V |
|
Result | Proceed to |
|---|---|
|
OK | A |
|
NG (w/ Smart Key System) |
B |
| NG (w/o Smart Key System) |
C |
| A |
| PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE |
| C |
| GO TO STEP 8 |
|
| 7. |
CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - 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 assembly.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection | Condition |
Specified Condition |
|---|---|---|
|
I223-24 (IGPD) - 2 (IGP-MAIN relay) |
Always | Below 1 Ω |
|
I223-24 (IGPD) or 2 (IGP-MAIN relay) - Body ground and other terminals |
Always | 10 kΩ or higher |
| OK | | GO TO SMART KEY SYSTEM
|
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
| 8. |
INSPECT IGNITION OR STARTER SWITCH ASSEMBLY |
Click here
| NG | | REPLACE IGNITION OR STARTER SWITCH ASSEMBLY |
|
| 9. |
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 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 (AUXILIARY BATTERY - IGNITION OR STARTER SWITCH ASSEMBLY) |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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