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.
2013 Toyota Prius ThreeFACTORY OEM SERVICE PROCEDURE
Problem Symptoms Table
WARNING: This page is about a different variant/trim than selected.
HINT:
- Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.
- Inspect the fuses and relays related to this system before inspecting the suspected areas below.
DYNAMIC RADAR CRUISE CONTROL SYSTEM
| Symptom | Suspected Area | Refer to |
|---|---|---|
| The cruise control system cannot be turned on using the cruise control switch (ON-OFF button). | Driving support ECU power source circuit | Refer to ECU Power Source Circuit |
| Cruise control switch circuit | Refer to Cruise Control Switch Circuit | |
| Cruise main indicator light circuit | Refer to Cruise Main Indicator Light Circuit | |
| Driving support ECU assembly | Refer to REMOVAL | |
| Cannot change between vehicle-to-vehicle distance control mode and constant speed control mode. | Cruise control switch circuit | Refer to Cruise Control Switch Circuit |
| Combination meter | Refer to REMOVAL | |
| Driving support ECU assembly | Refer to REMOVAL | |
| Set distance cannot be changed. | Distance control switch circuit | Refer to Distance Control Switch Circuit |
| Combination meter | Refer to REMOVAL | |
| Driving support ECU assembly | Refer to REMOVAL | |
| Cannot select vehicle-to-vehicle distance control mode. | Combination meter | Refer to REMOVAL |
| Millimeter wave radar sensor assembly | Refer to REMOVAL | |
| Driving support ECU assembly | Refer to REMOVAL | |
| Vehicle speed setting cannot be performed. (The cruise control indicator light remains illuminated on the combination meter when cruise control system is turned on using the cruise control switch (ON-OFF button), but turns off when the SET function is operated.) | Cruise control switch circuit | Refer to Cruise Control Switch Circuit |
| Driving support ECU assembly | Refer to REMOVAL | |
| Vehicle speed setting cannot be performed with constant speed control mode. (The cruise control indicator light remains illuminated on the combination meter when cruise control system is turned on using the cruise control switch (ON-OFF button), and remains on when the SET function is operated.) | Stop light switch circuit | Refer to DTC C1A05: Stop Light Switch Circuit; DTC C1A4B: Stop Light Relay Circuit |
| Vehicle speed sensor circuit | Refer to HOW TO PROCEED WITH TROUBLESHOOTING | |
| Cruise control switch circuit | Refer to Cruise Control Switch Circuit | |
| Hybrid control system | Refer to HOW TO PROCEED WITH TROUBLESHOOTING | |
| Electronically controlled brake system | Refer to HOW TO PROCEED WITH TROUBLESHOOTING | |
| Driving support ECU assembly | Refer to REMOVAL | |
| Vehicle speed setting cannot be performed with vehicle-to-vehicle distance control mode. (The cruise control indicator light remains illuminated on the combination meter when cruise control system is turned on using the cruise control switch (ON-OFF button), and remains on when the SET function is operated.) | Millimeter wave radar sensor assembly | Refer to REMOVAL |
| Stop light switch circuit | Refer to DTC C1A05: Stop Light Switch Circuit; DTC C1A4B: Stop Light Relay Circuit | |
| Vehicle speed sensor circuit | Refer to HOW TO PROCEED WITH TROUBLESHOOTING | |
| Cruise control switch circuit | Refer to Cruise Control Switch Circuit | |
| Hybrid control system | Refer to HOW TO PROCEED WITH TROUBLESHOOTING | |
| Wiper signal circuit | Refer to HOW TO PROCEED WITH TROUBLESHOOTING | |
| Electronically controlled brake system | Refer to HOW TO PROCEED WITH TROUBLESHOOTING | |
| Driving support ECU assembly | Refer to REMOVAL | |
| While vehicle is driven with the cruise control system controlling vehicle speed, the control of vehicle speed is canceled. | Stop light switch circuit | Refer to DTC C1A05: Stop Light Switch Circuit; DTC C1A4B: Stop Light Relay Circuit |
| Hybrid control system | Refer to HOW TO PROCEED WITH TROUBLESHOOTING | |
| Electronically controlled brake system | Refer to HOW TO PROCEED WITH TROUBLESHOOTING | |
| Cruise control switch circuit | Refer to Cruise Control Switch Circuit | |
| Combination meter | Refer to REMOVAL | |
| Vehicle speed sensor circuit | Refer to HOW TO PROCEED WITH TROUBLESHOOTING | |
| Wiper signal circuit | Refer to HOW TO PROCEED WITH TROUBLESHOOTING | |
| Driving support ECU assembly | Refer to REMOVAL | |
| Pulling back on the cruise control switch does not cancel vehicle speed control by the cruise control system. (The cruise control indicator light remains illuminated.) | Cruise control switch circuit | Refer to Cruise Control Switch Circuit |
| Combination meter | Refer to REMOVAL | |
| Driving support ECU assembly | Refer to REMOVAL | |
| Pulling back on the cruise control switch does not cancel vehicle speed control by the cruise control system. (The vehicle-to-vehicle cruise control indicator light goes out.) | Driving support ECU assembly | Refer to REMOVAL |
| Vehicle speed control by the cruise control system is not canceled when vehicle speed drops below the low speed limit. (The cruise control indicator light remains illuminated.) | Vehicle speed sensor circuit | Refer to HOW TO PROCEED WITH TROUBLESHOOTING |
| Combination meter | Refer to REMOVAL | |
| Driving support ECU assembly | Refer to REMOVAL | |
| Vehicle speed control by the cruise control system is not canceled when vehicle speed drops below the low speed limit. (The vehicle-to-vehicle cruise control indicator light goes out.) | Driving support ECU assembly | Refer to REMOVAL |
| Depressing the brake pedal does not cancel vehicle speed control by the cruise control system. (The cruise control indicator light remains illuminated.) | Stop light switch circuit | Refer to DTC C1A05: Stop Light Switch Circuit; DTC C1A4B: Stop Light Relay Circuit |
| Combination meter | Refer to REMOVAL | |
| Driving support ECU assembly | Refer to REMOVAL | |
| Depressing the brake pedal does not cancel vehicle speed control by the cruise control system. (The vehicle-to-vehicle cruise control indicator light goes out.) | Driving support ECU assembly | Refer to REMOVAL |
| Vehicle speed control by the cruise control system is not canceled when the wipers operate on HI. (The cruise control indicator light remains illuminated.) | Wiper signal circuit | Refer to HOW TO PROCEED WITH TROUBLESHOOTING |
| Combination meter | Refer to REMOVAL | |
| Driving support ECU assembly | Refer to REMOVAL | |
| Vehicle speed control by the cruise control system is not canceled when the wipers operate on HI. (The vehicle-to-vehicle cruise control indicator light goes out.) | Driving support ECU assembly | Refer to REMOVAL |
| Moving the shift lever does not cancel vehicle speed control by the cruise control system. (The cruise control indicator light remains illuminated.) | Hybrid control system | Refer to HOW TO PROCEED WITH TROUBLESHOOTING |
| Shift position sensor | Refer to HOW TO PROCEED WITH TROUBLESHOOTING | |
| Combination meter | Refer to REMOVAL | |
| Driving support ECU assembly | Refer to REMOVAL | |
| Moving the shift lever does not cancel vehicle speed control by the cruise control system. (The vehicle-to-vehicle cruise control indicator light goes out.) | Driving support ECU assembly | Refer to REMOVAL |
| Hunting (Speed is not constant.) | Vehicle speed sensor circuit | Refer to HOW TO PROCEED WITH TROUBLESHOOTING |
| SFI system | Refer to HOW TO PROCEED WITH TROUBLESHOOTING | |
| Hybrid control system | Refer to HOW TO PROCEED WITH TROUBLESHOOTING | |
| Driving support ECU assembly | Refer to REMOVAL | |
| Even though the front millimeter wave radar sensor is not dirty, "CLEAN RADAR SENSOR" is displayed. | Millimeter wave radar sensor assembly is dirty | - |
| Adjust front millimeter wave radar sensor assembly | Refer to ADJUSTMENT | |
| Millimeter wave radar sensor assembly | Refer to REMOVAL | |
| The beam axis of the millimeter wave radar sensor cannot be adjusted. | Check position, distance and angle of reflector | Refer to INSTALLATION |
| Check installation of millimeter wave radar sensor assembly | Refer to INSTALLATION | |
| Millimeter wave radar sensor assembly | Refer to REMOVAL | |
| Driving support ECU assembly | Refer to REMOVAL | |
| The warning buzzer does not sound. | Skid control buzzer circuit | Refer to Skid Control Buzzer Circuit |
| Electronically controlled brake system | Refer to HOW TO PROCEED WITH TROUBLESHOOTING | |
| Millimeter wave radar sensor assembly | Refer to REMOVAL | |
| Driving support ECU assembly | Refer to REMOVAL | |
| No brake control (when decelerating) | Electronically controlled brake system | Refer to HOW TO PROCEED WITH TROUBLESHOOTING |
| Driving support ECU assembly | Refer to REMOVAL | |
| The vehicle-to-vehicle distance control mode cruise control indicator light remains blinking. | TC and CG terminal circuit | Refer to TC and CG Terminal Circuit |
| Driving support ECU assembly | Refer to REMOVAL | |
| The cruise control SET indicator light does not illuminate. (Vehicle speed can be set) | Cruise control SET indicator light circuit | Refer to Cruise SET Indicator Light Circuit |
| Power management control ECU | Refer to REMOVAL | |
| The cruise control indicator light remains blinking. | TC and CG terminal circuit | Refer to TC and CG Terminal Circuit |
| Power management control ECU | Refer to REMOVAL |
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.