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.
Step 2 - Diagnosis System
- Description
- The HV control ECU has a self-diagnosis system by which malfunction in the computer itself or in THS components is detected and the Hybrid vehicle warning light in the multi-information display are lighted up.
- To check the Diagnostic Trouble Codes (DTC), connect the hand-held tester to the Data Link Connector 3 (DLC3) on the vehicle. The TOYOTA hand-held tester also enables you to erase the DTC and check freeze frame data and various forms of THS data.
- Freeze frame data:
As the freeze frame data records the driving condition when a malfunction is detected, when troubleshooting, it is useful for determining whether the vehicle was running, braked, stopped or reversed.
- Check the DLC3.
The HV control ECU conforms to ISO 14230 for communication.
The terminal arrangement of the DLC3 complies with SAEJ1962 and matches the ISO 14230 format.
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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.