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 TwoFACTORY OEM SERVICE PROCEDURE
Problem Symptoms Table
WARNING: This page is about a different variant/trim than selected.
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.
HEADLIGHT AND TAILLIGHT (FOR HALOGEN HEADLIGHT)
| Symptom | Suspected Area | Refer to |
|---|---|---|
| One low beam headlight does not illuminate. | Bulb | - |
| No. 1 integration relay | Refer to REMOVAL | |
| Harness or connector | - | |
| Both left and right low beam headlights do not illuminate. | Headlight dimmer switch circuit | Refer to Headlight Dimmer Switch Circuit |
| Low beam headlight circuit | Refer to Low Beam Headlight Circuit | |
| Main body ECU (Multiplex network body ECU) | Refer to REMOVAL | |
| One high beam headlight does not illuminate. | H-LP LH HI fuse or H-LP RH HI fuse | - |
| Bulb | - | |
| No. 1 integration relay | Refer to REMOVAL | |
| Harness or connector | - | |
| Both left and right high beam headlights do not illuminate. | H-LP HI MAIN FUSE | - |
| Headlight dimmer switch circuit | Refer to Headlight Dimmer Switch Circuit | |
| High beam headlight circuit | Refer to High Beam Headlight Circuit | |
| Main body ECU (Multiplex network body ECU) | Refer to REMOVAL | |
| "High Flash" (passing function) headlight does not illuminate (high beam headlights are normal). | Headlight dimmer switch circuit | Refer to Headlight Dimmer Switch Circuit |
| Main body ECU (Multiplex network body ECU) | Refer to REMOVAL | |
| One front parking light does not illuminate. | Bulb | - |
| Harness or connector | - | |
| One rear taillight does not illuminate. | Rear combination light assembly | Refer to ON-VEHICLE INSPECTION |
| Harness or connector | - | |
| One license plate light does not illuminate. | Bulb | - |
| Harness or connector | - | |
| One front side marker light does not illuminate. | Bulb | - |
| Harness or connector | - | |
| One rear side marker light does not illuminate. | Rear combination light assembly | Refer to ON-VEHICLE INSPECTION |
| Harness or connector | - | |
| All of the lights (rear taillights, front side marker lights, parking lights, license plate lights and rear side marker lights) do not illuminate. (TAIL fuse is normal.) | TAIL fuse | - |
| Headlight dimmer switch circuit | Refer to Headlight Dimmer Switch Circuit | |
| Taillight relay circuit | Refer to Taillight Relay Circuit | |
| Main body ECU (Multiplex network body ECU) | Refer to REMOVAL | |
| All of the lights (rear taillights, front side marker lights, parking lights, license plate lights and rear side marker lights) do not illuminate. (Although the TAIL fuse is replaced the fuse breaks again.) | License palate light assembly | Refer to INSPECTION |
| Rear combination light assembly | Refer to ON-VEHICLE INSPECTION | |
| Headlight assembly | Refer to REMOVAL | |
| Harness or connector | - |
HEADLIGHT AND TAILLIGHT (FOR LED HEADLIGHT)
| Symptom | Suspected Area | Refer to |
|---|---|---|
| One low beam headlight does not illuminate. | Check DTCs | - |
| Light control ECU | Refer to REMOVAL | |
| No. 1 integration relay | Refer to REMOVAL | |
| Headlight unit | Refer to REMOVAL | |
| Harness or connector | - | |
| Both left and right low beam headlights do not illuminate. | Check DTCs | Refer to DTC CHECK / CLEAR |
| Headlight dimmer switch circuit | Refer to Headlight Dimmer Switch Circuit | |
| Low beam headlight circuit | Refer to Low Beam Headlight Circuit | |
| Main body ECU (Multiplex network body ECU) | Refer to REMOVAL | |
| "High Flash" (passing function) headlight does not illuminate (high beam headlights are normal). | Headlight dimmer switch circuit | Refer to Headlight Dimmer Switch Circuit |
| Main body ECU (Multiplex network body ECU) | Refer to REMOVAL | |
| One front parking light does not illuminate. | Bulb | - |
| Harness or connector | - | |
| One rear taillight does not illuminate. | Rear combination light assembly | Refer to ON-VEHICLE INSPECTION |
| Harness or connector | - | |
| One license plate light does not illuminate. | Bulb | - |
| Harness or connector | - | |
| One front side marker light does not illuminate. | Bulb | - |
| Harness or connector | - | |
| One rear side marker light does not illuminate. | Rear combination light assembly | Refer to ON-VEHICLE INSPECTION |
| Harness or connector | - | |
| All of the lights (rear taillights, front side marker lights, parking lights, license plate lights and rear side marker lights) do not illuminate. (TAIL fuse is normal.) | TAIL fuse | - |
| Headlight dimmer switch circuit | Refer to Headlight Dimmer Switch Circuit | |
| Taillight relay circuit | Refer to Taillight Relay Circuit | |
| Main body ECU (Multiplex network body ECU) | Refer to REMOVAL | |
| All of the lights (rear taillights, front side marker lights, parking lights, license plate lights and rear side marker lights) do not illuminate. (Although the TAIL fuse is replaced the fuse breaks again.) | License palate light assembly | Refer to INSPECTION |
| Rear combination light assembly | Refer to ON-VEHICLE INSPECTION | |
| Headlight assembly | Refer to REMOVAL | |
| Harness or connector | - |
STOP LIGHT
| Symptom | Suspected Area | Refer to |
|---|---|---|
| One side stop light does not illuminate. | Rear combination light assembly | Refer to ON-VEHICLE INSPECTION |
| Harness or connector | - | |
| High mounted stop light does not illuminate. | High mounted stop light assembly | Refer to INSPECTION |
| Harness or connector | - | |
| All of the stop lights do not illuminate. | STOP fuse | - |
| Stop light switch assembly | Refer to INSPECTION | |
| Stop light control ECU assembly | Refer to INSPECTION | |
| Harness or connector | - | |
| Stop lights remain on. | Electronically controlled brake system | Refer to HOW TO PROCEED WITH TROUBLESHOOTING |
| Stop light switch assembly | Refer to INSPECTION | |
| Stop light control ECU assembly | Refer to INSPECTION | |
| Harness or connector | - | |
| Brake booster with master cylinder assembly | Refer to REMOVAL |
FRONT FOG LIGHT
| Symptom | Suspected Area | Refer to |
|---|---|---|
| One front fog light does not illuminate. | Bulb | - |
| Harness or connector | - | |
| Both left and right front fog lights do not illuminate (taillights are normal). | FR FOG fuse | - |
| Headlight dimmer switch circuit | Refer to Headlight Dimmer Switch Circuit | |
| Front fog light circuit | Refer to Front Fog Light Circuit | |
| Main body ECU (Multiplex network body ECU) | Refer to REMOVAL |
BACK-UP LIGHT
| Symptom | Suspected Area | Refer to |
|---|---|---|
| One back-up light does not illuminate. | Bulb | - |
| Harness or connector | - | |
| Both left and right back-up lights do not illuminate. | P/I 2 fuse | - |
| Back-up light circuit | Refer to Back-up Light Circuit | |
| Power management control ECU | Refer to REMOVAL |
TURN SIGNAL LIGHT
| Symptom | Suspected Area | Refer to |
|---|---|---|
| One turn signal light does not operate (except side turn signal lights). | Bulb | - |
| Harness or connector | - | |
| Turn signal lights do not operate in one direction. | Headlight dimmer switch assembly (Turn signal light switch) | Refer to INSPECTION |
| Turn signal flasher assembly | Refer to INSPECTION | |
| Harness or connector | - | |
| All turn signal lights do not operate. | ECU-IG NO. 2 fuse | - |
| HAZ fuse | - | |
| Headlight dimmer switch assembly (Turn signal light switch) | Refer to INSPECTION | |
| Turn signal flasher assembly | Refer to INSPECTION | |
| Harness or connector | - | |
| All turn signal lights do not flash at the correct speed. | Bulb | - |
| Turn signal flasher assembly | Refer to INSPECTION | |
| Harness or connector | - |
HAZARD WARNING LIGHT
| Symptom | Suspected Area | Refer to |
|---|---|---|
| Hazard warning lights do not operate. | HAZ fuse | - |
| ECU-IG NO. 2 fuse | - | |
| Hazard warning switch | Refer to INSPECTION | |
| Turn signal flasher assembly | Refer to INSPECTION | |
| Harness or connector | - | |
| Hazard warning lights operate when the hazard warning switch is not turned on. | Electronically controlled brake system | Refer to HOW TO PROCEED WITH TROUBLESHOOTING |
| Hazard warning switch | Refer to INSPECTION | |
| Turn signal flasher assembly | Refer to INSPECTION | |
| Harness or connector | - | |
| Brake booster with master cylinder assembly | Refer to REMOVAL | |
| Main body ECU (Multiplex network body ECU) | Refer to REMOVAL |
AUTOMATIC LIGHT CONTROL SYSTEM
| Symptom | Suspected Area | Refer to |
|---|---|---|
| Automatic light control system does not operate. | Check DTCs | Refer to DTC CHECK / CLEAR |
| Headlight dimmer switch circuit | Refer to Headlight Dimmer Switch Circuit | |
| IG signal circuit | Refer to IG Signal Circuit | |
| Main body ECU (Multiplex network body ECU) | Refer to REMOVAL |
LIGHT AUTO TURN-OFF SYSTEM
| Symptom | Suspected Area | Refer to |
|---|---|---|
| Light auto turn-off system does not operate. | Headlight dimmer switch circuit | Refer to Headlight Dimmer Switch Circuit |
| Front door courtesy switch circuit | Refer to Front Door Courtesy Switch Circuit | |
| Rear door courtesy switch circuit | Refer to Rear Door Courtesy Switch Circuit | |
| Door unlock detection switch circuit | Refer to Door Unlock Detection Switch Circuit | |
| IG signal circuit | Refer to IG Signal Circuit | |
| Main body ECU (Multiplex network body ECU) | Refer to REMOVAL |
DAYTIME RUNNING LIGHT SYSTEM
| Symptom | Suspected Area | Refer to |
|---|---|---|
| Daytime running light system does not operate. | CAN communication system | Refer to HOW TO PROCEED WITH TROUBLESHOOTING |
| Headlight dimmer switch circuit | Refer to Headlight Dimmer Switch Circuit | |
| IG signal circuit | Refer to IG Signal Circuit | |
| Parking brake switch circuit | Refer to Parking Brake Switch Circuit | |
| Daytime running light relay circuit | Refer to Daytime Running Light Relay Circuit | |
| Main body ECU (Multiplex network body ECU) | Refer to REMOVAL |
CHARGING INLET LIGHT (CHARGE LID LIGHT)
| Symptom | Suspected Area | Refer to |
|---|---|---|
| Charge lid light does not operate. | Spot light assembly | Refer to INSPECTION |
| Indicator light assembly (Courtesy switch inspection) | Refer to INSPECTION | |
| Harness or connector | - | |
| Plugin charge control ECU assembly | 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.