Steps to take in an emergency -> If the hybrid system will not start for Your Toyota Prius 4 Door Fourth Generation (2016-2022)

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7-2. Steps to take in an emergency  
If the hybrid system will not start  
Reasons for the hybrid system not starting vary depending on  
the situation. Check the following and perform the appropriate  
procedure:  
The hybrid system will not start even though the correct starting  
procedure is being followed. (P. 241)  
One of the following may be the cause of the problem:  
The electronic key may not be functioning properly.* (P. 635)  
There may not be sufficient fuel in the vehicle’s tank.  
Refuel the vehicle. (P. 89)  
There may be a malfunction in the immobilizer system.* (P. 94)  
There may be a malfunction in the shift control system.*  
(P. 245, 597)  
The hybrid system may be malfunctioning due to an electrical prob-  
lem such as electronic key battery depletion or a blown fuse. How-  
ever, depending on the type of malfunction, an interim measure is  
available to start the hybrid system. (P. 634)  
There is a possibility that the temperature of the hybrid battery  
(traction battery) is extremely low (approximately below -22°F  
[-30°C]). (P. 89, 244)  
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*: It may not be possible to shift the shift position other than P.  
The interior lights and headlights are dim, or the horn does not  
sound or sounds at a low volume.  
One of the following may be the cause of the problem:  
The 12-volt battery may be discharged. (P. 638)  
The 12-volt battery terminal connections may be loose or corroded.  
(P. 512)  
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634  
7-2. Steps to take in an emergency  
The interior lights and headlights do not turn on, or the horn  
does not sound.  
One of the following may be the cause of the problem:  
The 12-volt battery may be discharged. (P. 638)  
One or both of the 12-volt battery terminals may be disconnected.  
(P. 512)  
Contact your Toyota dealer if the problem cannot be repaired, or if repair  
procedures are unknown.  
Emergency start function  
When the hybrid system does not start, the following steps can be  
used as an interim measure to start the hybrid system if the power  
switch is functioning normally.  
Do not use this starting procedure except in cases of emergency.  
1
Set the parking brake.  
2
Turn the power switch to ACCESSORY mode.  
3
Press and hold the power switch for about 15 seconds while  
depressing the brake pedal firmly.  
Even if the hybrid system can be started using the above steps, the  
system may be malfunctioning. Have the vehicle inspected by your  
Toyota dealer.  
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