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.
2003 Toyota PriusFACTORY OEM SERVICE PROCEDURE
Hybrid Vehicle Electronic Control Unit Programming
NOTE:
Following procedure is for only programming the Hybrid Vehicle Electronic Control Unit (HV ECU) for engine immobilizer system operation when only HV ECU is replaced. Engine immobilizer system may also be referred to as Hybrid Vehicle (HV) immobilizer system. For programming of ignition key and transponder key Electronic Control Unit (ECU) for engine immobilizer system, see IMMOBILIZER COMPONENT REPLACEMENT PROGRAMMING (PRIUS)
in COMPUTER RELEARN PROCEDURES - TOYOTA article in GENERAL INFORMATION.
Factory Service Tools
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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.
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