Lexus IS250 IS220d GSE20 ALE20 4GR-FSE ENGINE CONTROL SYSTEM
DESCRIPTION
WIRING DIAGRAM
INSPECTION PROCEDURE
CHECK CRANKING
READ VALUE OF INTELLIGENT TESTER (STA SIGNAL)
INSPECT ECM (STAR AND STSW VOLTAGE)
INSPECT ST CUT RELAY
INSPECT PARK / NEUTRAL POSITION SWITCH (A/T) OR CLUTCH SWITCH ASSEMBLY (M/T)
INSPECT STARTER RELAY
CHECK HARNESS AND CONNECTOR (PARK/NEUTRAL POSITION SWITCH - STARTER RELAY)
INSPECT ENGINE ROOM RELAY BLOCK (STARTER RELAY VOLTAGE)
INSPECT STARTER ASSEMBLY
CHECK HARNESS AND CONNECTOR (POWER SOURCE CONTROL ECU - ECM)
SFI 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 to the START position, check whether the starter motor starts.
| 3.INSPECT ECM (STAR AND STSW VOLTAGE) |
Measure the voltage of the A5 and E4 ECM connectors while cranking the engine.
- Standard voltage:
| Tester Connection | Specified Condition |
| STAR (E4-4) - E1 (E4-7) | 9 to 14 V |
| STSW (A5-19) - E1 (E4-7) | 9 to 14 V |
- Result:
| Terminal STAR | Terminal STSW | Proceed to |
| 9 to 14 V | 9 to 14 V | A |
| 0 V | 9 to 14 V | B |
| 0 V | 0 V | C |
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) |
| 5.INSPECT PARK / NEUTRAL POSITION SWITCH (A/T) OR CLUTCH SWITCH ASSEMBLY (M/T) |
Disconnect the park/neutral position (PNP) switch (A/T) or clutch switch (M/T) connector.
Measure the resistance between each terminal shown below when the shift lever is moved to each range.
- Standard resistance (A/T):
| Shift Position | Tester Connection | Specified Condition |
| P | 4 - 5 | Below 1 Ω |
| N | 4 - 5 | Below 1 Ω |
- Standard resistance (M/T):
| Clutch Pedal Operation | Tester Connection | Specified Condition |
| Depressed | 1 - 2 | Below 1 Ω |
| | REPLACE PARK / NEUTRAL POSITION SWITCH (A/T) OR CLUTCH SWITCH ASSEMBLY (M/T) |
|
|
| OK | |
| |
| CHECK AND REPAIR HARNESS AND CONNECTOR ((PARK/NEUTRAL POSITION SWITCH - ECM, ECM - ST CUT RELAY, ST) |
|
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) |
| 7.CHECK HARNESS AND CONNECTOR (PARK/NEUTRAL POSITION SWITCH - STARTER RELAY) |
Check the harness and the connectors between the park/neutral position switch and the starter relay.
Disconnect the E45*1, A24*2 switch connector.
*1: A/T
*2: M/T
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 (A/T) (Check for open):
| Tester Connection | Specified Condition |
| Park/Neutral position switch (E45-5) - Starter relay (1) | Below 1 Ω |
- Standard resistance (M/T) (Check for open):
| Tester Connection | Specified Condition |
| Clutch start switch (A24-2) - Starter relay (1) | Below 1 Ω |
- Standard resistance (A/T) (Check for short):
| Tester Connection | Specified Condition |
| Park/Neutral position switch (E45-5) or Starter relay (1) - Body ground | 10 kΩ or higher |
- Standard resistance (M/T) (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 |
|
|
| 8.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 |
|
|
| 9.INSPECT STARTER ASSEMBLY |
| | REPAIR OR REPLACE STARTER ASSEMBLY |
|
|
| OK | |
| |
| REPAIR OR REPLACE HARNESS OR CONNECTOR (STARTER RELAY - STARTER, STARTER - BATTERY) |
|
| 10.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 A5 ECM connector.
Measure the resistance of the wire harness side connectors.
- Standard resistance (Check for open):
| Tester Connection | Specified Condition |
| J55-39 (STSW) - A5-19 (STSW) | Below 1 Ω |
- Standard resistance (Check for short):
| Tester Connection | Specified Condition |
| J55-39 (STSW) or A5-19 (STSW) - Body ground | 10 kΩ or higher |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
| OK | |
| |
| GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START |
|
LEXUS IS250, IS220d / GSE20 ALE20
