Lexus IS250 IS220d GSE20 ALE20 4GR-FSE ENGINE CONTROL SYSTEM
DESCRIPTION
WIRING DIAGRAM
INSPECTION PROCEDURE
INSPECT ECM (+B, +B1 VOLTAGE)
CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND)
INSPECT ECM (IGSW VOLTAGE)
CHECK FUSE (IGN FUSE)
INSPECT IG2 RELAY
INSPECT ECM (MREL VOLTAGE)
CHECK FUSE (EFI FUSE)
INSPECT INTEGRATION RELAY (EFI MAIN RELAY)
CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY- ECM, INTEGRATION RELAY - BODY GROUND)
SFI SYSTEM - ECM Power Source Circuit
DESCRIPTION
When the engine switch is turned to on, the battery voltage is applied to terminal IGSW of the ECM. The ECM MREL output signal causes a current to flow to the coil, closing the contacts of the EFI MAIN relay and supplying power to terminal +B of the ECM.
If the engine switch is turned to off, the ECM holds the EFI MAIN relay ON for a maximum of 2 seconds to allow for the initial setting of the throttle valve.
When the engine switch is turned on (IG), voltage from the ECM's MREL terminal flows to the integration relay (EFI MAIN relay). This causes the contacts of the integration relay (EFI MAIN relay) to close, which supplies power to terminal +B or +B1 of the ECM.
WIRING DIAGRAM
INSPECTION PROCEDURE
| 1.INSPECT ECM (+B, +B1 VOLTAGE) |
Turn the engine switch on (IG).
Measure the voltage of the A5 and E4 ECM connectors.
- Standard voltage:
| Tester Connection | Specified Condition |
| +B (A5-6) - E1 (E4-7) | 9 to 14 V |
| +B1 (A5-5) - E1 (E4-7) | 9 to 14 V |
Remove the IGN fuse from the cowl side junction block RH.
Measure the resistance of the IGN fuse .
- Standard resistance:
- Below 1 Ω
Remove the IG2 relay from the engine room J/B and R/B No. 2.
Measure the resistance of the IG2 relay.
- Standard resistance:
| Tester Connection | Specified Condition |
| 3 - 5 | 10 kΩ or higher |
| 3 - 5 | Below 1 Ω
(when battery voltage applied to terminals 1 and 2) |
| OK | |
| |
| CHECK AND REPAIR SMART ACCESS SYSTEM WITH PUSH-BUTTON START |
|
| 6.INSPECT ECM (MREL VOLTAGE) |
Turn the engine switch on (IG).
Measure the voltage of the A5 and E4 ECM connectors.
- Standard voltage:
| Tester Connection | Specified Condition |
| MREL (A5-13) - E1 (E4-7) | 9 to 14 V |
Remove the EFI fuse from the engine room J/B and R/B No. 2.
Measure the resistance of the EFI fuse.
- Standard resistance:
- Below 1 Ω
| 8.INSPECT INTEGRATION RELAY (EFI MAIN RELAY) |
Remove the integration relay from the engine room J/B and R/B No. 2.
Measure the resistance of the EFI MAIN relay.
- Standard resistance:
| Tester Connection | Specified Condition |
| 2C-1 - 2A-8 | 10 kΩ or higher |
Below 1 Ω
(when battery voltage applied to terminals 2A-6 and 2A-7) |
| | REPLACE INTEGRATION RELAY |
|
|
| 9.CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY- ECM, INTEGRATION RELAY - BODY GROUND) |
Check the harness and the connectors between the integration relay and the ECM.
Remove the integration relay from the engine room J/B and R/B No. 2.
Disconnect the A5 ECM connector.
Measure the resistance of the wire harness side connectors.
- Standard resistance (Check for open):
| Tester Connection | Specified Condition |
| 2A-6 - MREL (A5-13) | Below 1 Ω |
- Standard resistance (Check for short):
| Tester Connection | Specified Condition |
| 2A-6 or MREL (A5-13) - Body ground | 10 kΩ or higher |
Check the harness and the connectors between the integration relay and body ground.
Remove the integration relay from the engine room J/B and R/B No. 2.
Measure the resistance of the wire harness side connector and body ground.
- Standard resistance (Check for open):
| Tester Connection | Specified condition |
| 2A-7 - Body ground | Below 1 Ω |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
| OK | |
| |
| CHECK AND REPAIR HARNESS AND CONNECTOR (TERMINAL +B OF ECM - BATTERY POSITIVE TERMINAL) |
|
LEXUS IS250, IS220d / GSE20 ALE20
