Lexus IS250 IS220d GSE20 ALE20 2AD-FHV ENGINE CONTROL SYSTEM
DESCRIPTION
WIRING DIAGRAM
INSPECTION PROCEDURE
CHECK CRANKING
READ VALUE OF INTELLIGENT TESTER (STA SIGNAL)
INSPECT ECM (STSW VOLTAGE)
INSPECT ECM (STAR VOLTAGE)
INSPECT ST CUT RELAY
INSPECT CLUTCH SWITCH ASSEMBLY
INSPECT STARTER RELAY
CHECK HARNESS AND CONNECTOR (CLUTCH START SWITCH - STARTER RELAY)
INSPECT ENGINE ROOM RELAY BLOCK (STARTER RELAY VOLTAGE)
INSPECT STARTER ASSEMBLY
CHECK HARNESS AND CONNECTOR (POWER SOURCE CONTROL ECU - ECM)
ECD SYSTEM - Cranking Holding Function Circuit
DESCRIPTION
The cranking holding control system provides current to the starter when the ECM detects the engine switch's start signal (STSW). When the ECM performs a firing judgment, the system cuts current to the starter. When an ECM receives the STSW signal, it turns on the ST CUT relay, which prevents flickering of the combination meter, clock, audio system, etc. Also, the ECM sends a signal to the ECM's STAR terminal. Then the STAR output signal travels through the park/neutral position (PNP) switch to the STARTER relay, causing the starter to activate.
When the engine is cranking, the starter operation signal is sent to the ECM's STA terminal.
WIRING DIAGRAM
Refer to DTC P0617 .
INSPECTION PROCEDURE
When turning the engine switch on (START), check whether the starter motor starts.
| 3.INSPECT ECM (STSW VOLTAGE) |
Disconnect the A49 ECM connector.
Measure the voltage between the terminals of the ECM connector and body ground while cranking the engine.
- Standard voltage:
| Tester Connection | Specified Condition |
| STSW (A49-9) - Body ground | 9 to 14 V |
Reconnect the ECM connector.
| 4.INSPECT ECM (STAR VOLTAGE) |
Remove the ST CUT relay from engine room J/B and R/B No. 2.
Measure the voltage between the terminals of the engine room J/B and R/B No. 2 and body ground while cranking the engine.
- Standard voltage:
| Tester Connection | Specified Condition |
| ST CUT relay (1) - Body ground | 9 to 14 V |
Reinstall the ST CUT relay.
Remove the ST CUT relay from the engine room J/B and R/B No. 2.
Measure the resistance of the ST CUT 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) |
| 6.INSPECT CLUTCH SWITCH ASSEMBLY |
Disconnect the clutch switch connector.
Measure the resistance between each terminal shown below when the shift lever is moved to each range.
- Standard resistance:
| Clutch Pedal Operation | Tester Connection | Specified Condition |
| Depressed | 1 - 2 | Below 1 Ω |
| | REPLACE CLUTCH SWITCH ASSEMBLY |
|
|
| OK | |
| |
| CHECK AND REPAIR HARNESS AND CONNECTOR (CLUTCH START SW - ECM, CLUTCH START SW - ST CUT RELAY) |
|
Remove the starter relay from the engine room J/B and R/B No. 1.
Measure the resistance of the starter 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) |
| 8.CHECK HARNESS AND CONNECTOR (CLUTCH START SWITCH - STARTER RELAY) |
Check the harness and the connectors between the park/neutral position switch and the starter relay.
Disconnect the A42 switch connector.
Remove the starter relay from the engine room J/B and R/B No. 1.
Measure the resistance of the wire harness side connectors.
- Standard resistance (Check for open):
| Tester Connection | Specified Condition |
| Clutch start switch (A24-2) - Starter relay (1) | Below 1 Ω |
- Standard resistance (Check for short):
| Tester Connection | Specified Condition |
| Clutch start switch (A24-2) or Starter relay (1) - Body ground | 10 kΩ or higher |
Check the harness and the connector between the starter relay and the body ground.
Remove the starter relay from the engine room J/B and R/B No. 1.
Measure the resistance of the starter relay and the body ground.
- Standard resistance (Check for open):
| Tester Connection | Specified Condition |
| Starter relay (2) - Body ground | Below 1 Ω |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
| 9.INSPECT ENGINE ROOM RELAY BLOCK (STARTER RELAY VOLTAGE) |
Remove the starter relay from the engine room J/B and R/B No. 1.
Measure the voltage of the engine room J/B and R/B No. 1 and the body ground.
- Standard voltage:
| Tester Connection | Specified Condition |
| Starter relay (5) - Body ground | 9 to 14 V |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
| 10.INSPECT STARTER ASSEMBLY |
| | REPAIR OR REPLACE STARTER ASSEMBLY |
|
|
| OK | |
| |
| REPAIR OR REPLACE HARNESS OR CONNECTOR (STARTER RELAY - STARTER, STARTER - BATTERY) |
|
| 11.CHECK HARNESS AND CONNECTOR (POWER SOURCE CONTROL ECU - ECM) |
Check the harness and the connectors between the power source control ECU and ECM.
Disconnect the power source control ECU connector.
Disconnect the A49 ECM connector.
Measure the resistance of the wire harness side connectors.
- Standard resistance (Check for open):
| Tester Connection | Specified Condition |
| J55-39 (STSW) - A49-9 (STSW) | Below 1 Ω |
- Standard resistance (Check for short):
| Tester Connection | Specified Condition |
| J55-39 (STSW) or A49-9 (STSW) - Body ground | 10 kΩ or higher |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
| OK | |
| |
| GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START |
|
