Lexus IS250 IS220d GSE20 ALE20 2AD-FHV ENGINE CONTROL SYSTEM

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND)

CHECK ECM TERMINAL VOLTAGE (IGSW TERMINAL)

INSPECT FUSE (IGN FUSE)

CHECK TERMINAL VOLTAGE (EFI MAIN RELAY TERMINAL)

INSPECT FUSE (ECD FUSE)

INSPECT EFI MAIN RELAY

CHECK HARNESS AND CONNECTOR (MAIN RELAY - ECM)

ECD SYSTEM - ECM Power Source Circuit

DESCRIPTION

When the engine switch is turned ON (IG), 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 MAIN relay and supplying power to terminal +B of the ECM.


WIRING DIAGRAM

Ecd System - Ecm Power Source Circuit. 2AD-FHV ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

INSPECTION PROCEDURE

  • NOTICE:
  • After replacing the ECM, the new ECM needs registration and initialization .
1.CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND)
Ecd System - Ecm Power Source Circuit. 2AD-FHV ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

Disconnect the E59 ECM connector.

Measure the resistance of the wire harness side connector.

  • Standard resistance:
  • Tester ConnectionSpecified Condition
    E1 (E59-109) - Body groundBelow 1 Ω
NG
Go to step 4
NG
3.INSPECT FUSE (IGN FUSE)
Ecd System - Ecm Power Source Circuit. 2AD-FHV ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

Remove the IGN fuse from the cowl side J/B LH.

Measure the resistance of the fuse.

  • Standard resistance:
  • Below 1 Ω
NG
Go to step 7
OK
5.INSPECT FUSE (ECD FUSE)
Ecd System - Ecm Power Source Circuit. 2AD-FHV ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

Remove the ECD fuse from the engine room J/B and R/B No. 2.

Measure the resistance of the fuse.

  • Standard resistance:
  • Below 1 Ω
NG
REPLACE FUSE
OK
6.INSPECT EFI MAIN RELAY
Ecd System - Ecm Power Source Circuit. 2AD-FHV ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

Remove the EFI MAIN relay from the engine room R/B No. 2.

Inspect the EFI MAIN relay.

  • Standard resistance:
  • Tester ConnectionSpecified Condition
    3 - 510 kΩ or higher
    Below 1 Ω
    (Apply battery voltage to terminals 1 and 2)

Reinstall the EFI MAIN relay.

NG
REPLACE ECM
OK
7.CHECK HARNESS AND CONNECTOR (MAIN RELAY - ECM)
Ecd System - Ecm Power Source Circuit. 2AD-FHV ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

Check the harness and connector between the EFI MAIN relay and ECM.


Remove the EFI MAIN relay from the engine room J/B and R/B No. 2.

Disconnect the A49 ECM connector.

Check the resistance between the wire harness side connectors.

  • Standard resistance (Check for open):
  • Tester ConnectionSpecified Condition
    EFI MAIN relay (1) - MREL (A49-45)Below 1 Ω
  • Standard resistance (Check for short):
  • Tester ConnectionSpecified Condition
    EFI MAIN relay (1) or MREL (A49-45) - Body ground10 kΩ or higher

Reconnect the ECM connector.

Check the harness and connector between the EFI MAIN relay and body ground.


Remove the EFI MAIN relay from the engine room J/B and R/B No. 2.

Check the resistance between the wire harness side connector and body ground.

  • Standard resistance (Check for open):
  • Tester ConnectionSpecified Condition
    EFI MAIN relay (2) - Body groundBelow 1 Ω

Reinstall the EFI MAIN relay.

NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (MAIN RELAY - ECM)
OK
REPLACE ECM
LEXUS IS250, IS220d / GSE20 ALE20
2AD-FHV ENGINE CONTROL SYSTEM
Lexus IS250 IS220d GSE20 ALE20
ECD SYSTEM