Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSLEXUS2012IS 250C V6-2.5L (4GR-FSE)REPAIR AND DIAGNOSISACCESSORIES AND OPTIONAL EQUIPMENTANTITHEFT AND ALARM SYSTEMSTESTING AND INSPECTIONSYMPTOM RELATED DIAGNOSTIC PROCEDURESSMART ACCESS SYSTEM WITH PUSH-BUTTON START (FOR ENTRY FUNCTION)FRONT PASSENGER SIDE DOOR ENTRY LOCK FUNCTION DOES NOT OPERATE
2012 Lexus IS 250C V6-2.5L (4GR-FSE)
Front Passenger Side Door Entry Lock Function Does Not Operate
2012 Lexus IS 250C V6-2.5L (4GR-FSE)SECTION Front Passenger Side Door Entry Lock Function Does Not Operate
THEFT DETERRENT / KEYLESS ENTRY: SMART ACCESS SYSTEM WITH PUSH-BUTTON START (for Entry Function): Front Passenger Side Door Entry Lock Function does not Operate
- Front Passenger Side Door Entry Lock Function does not Operate
DESCRIPTION
If the front passenger door entry unlock function operates normally, but its entry lock function does not, this means that the request code from the front passenger door is being output normally. In this case, a malfunction in the lock switch circuit (from the certification ECU (smart key ECU assembly) to the front door outside handle assembly (lock switch)) is suspected.
WIRING DIAGRAM
INSPECTION PROCEDURE
NOTICE:
* The smart access system with push-button start (for entry function) uses a LIN communication system and BEAN communication system. Inspect the communication function by following How to Proceed with Troubleshooting How To Proceed With Troubleshooting. Troubleshoot the smart access system with push-button start (for entry function) after confirming that the communication system is functioning properly.
* Confirm that another key is not in the cabin.
PROCEDURE
1. CHECK POWER DOOR LOCK OPERATION
(a) When the door control switch on the master switch assembly is operated, check that the doors unlock and lock according to switch operation Operation Check.
OK:
Door locks operate normally.
NG -- GO TO POWER DOOR LOCK CONTROL SYSTEM (Proceed to Problem Symptoms Table) Problem Symptoms Table
OK -- Continue to next step.
2. READ VALUE USING TECHSTREAM (DOOR UNLOCK DETECTION SWITCH)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream on.
(d) Enter the following menus: Body Electrical / Body / Data List.
(e) Read the Data List according to the display on the Techstream.
Body (Main Body ECU RH (Cowl Side Junction Block RH))
OK:
On the Techstream screen, the display changes between ON and OFF according to the chart above.
Result:
B -- GO TO POWER DOOR LOCK CONTROL SYSTEM (Proceed to Problem Symptoms Table) Problem Symptoms Table
A -- Continue to next step.
3. READ VALUE USING TECHSTREAM (DOOR OUTSIDE HANDLE)
(a) Enter the following menus: Body Electrical / Smart Access / Data List.
(b) Read the Data List according to the display on the Techstream.
Smart Access (Certification ECU (Smart Key ECU Assembly))
OK:
On the Techstream screen, the display changes between ON and OFF according to the chart above.
NG -- CHECK HARNESS AND CONNECTOR (FRONT DOOR OUTSIDE HANDLE - DOOR ELECTRICAL KEY OSCILLATOR)
OK -- REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) Removal
4. CHECK HARNESS AND CONNECTOR (FRONT DOOR OUTSIDE HANDLE - DOOR ELECTRICAL KEY OSCILLATOR)
(a) Disconnect the front door outside handle assembly (for front passenger side) connector.
(b) Disconnect the door electrical key oscillator (for front passenger side) connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
5. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - FRONT DOOR OUTSIDE HANDLE)
(a) Disconnect the certification ECU (smart key ECU assembly) connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
6. INSPECT FRONT DOOR OUTSIDE HANDLE ASSEMBLY (for Front Passenger Side)
(a) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- REPLACE FRONT DOOR OUTSIDE HANDLE ASSEMBLY (for Front Passenger Side) Removal
OK -- Continue to next step.
7. REPLACE DOOR ELECTRICAL KEY OSCILLATOR (for Front Passenger Side)
(a) Replace the door electrical key oscillator (for front passenger side) Removal.
NEXT -- Continue to next step.
8. CHECK DOOR ELECTRICAL KEY OSCILLATOR (FRONT PASSENGER SIDE OPERATION)
(a) Check that the entry functions operate normally Operation Check.
OK:
Entry functions operate normally.
NG -- REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) Removal
OK -- END (DOOR ELECTRICAL KEY OSCILLATOR WAS DEFECTIVE)
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.