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.
Engine does not Start: Description
2010 Lexus LS 460L AWDSECTION Description
- ENGINE START SYSTEM OPERATION
- When the engine switch is pressed with the brake pedal depressed and shift lever in P or N, the main body ECU determines that it is an engine start request.
- The certification ECU and other ECUs perform key verification via the LIN communication line. The engine switch indicator light illuminates in green.
- The main body ECU activates the D-ACC, D-IG1 and IG2 relays.
- The certification ECU outputs a steering UNLOCK signal. The signal is sent to the steering lock ECU via the LIN communication line.
- The main body ECU sends an engine start request signal to the ECM.
- The ECM sends an ACC cut request signal to the main body ECU.
- The ECM and main body ECU activate the ST cut relay.
- The main body ECU deactivates the D-ACC relay until the ECU detects an engine start.
- The ECU reactivates the D-ACC relay and turns off the engine switch indicator light.
Symbols of main body ECU Signals SSW1/SSW2 Engine switch on (ACC, IG) signal ACCD D-ACC relay operation signal IG2D IG2 relay operation signal STR2 ST CUT relay operation signal STR Park / neutral position switch signal STP Stop light switch signal TACH Engine start detection signal STSW Starter activation request signal ACCR ACC cut request signal
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:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.