Here's the deal. My parents own a 2008 Prius Touring package, not sure exactly which Touring though. We bought it a few months ago and recently have been having problems starting it. There have been several cases of not being able to start it. Case 1 1. Parked on incline 2. Leave and lock the Prius. 3. Return to Prius after some time. 4. Press brake, then Start button. 5. A few regular, dashboard lights show up plus an exclamation point in a triangle symbol. 6. Won't start. 7. After a while, car is too low on batteries to start. 8. Jump start...Now works. Case 2 1. Leave fob in car with my sleeping brother in the Prius for about 1.5 hours. 2. Prius is parked on slight incline. 3. Won't start. 4. Too low to start after several tries to start. 5. Discovered its low on gas. 6. Needed gas and jumpstart to work. Case 3 1. Locked and left Prius on incline driveway. 2. Return in morning, won't start. 3. Rolled on to level surface after receiving message about car not parked on level surface and a problem with transmission. 4. Started up after that. Case 4 1. Locked and left dog in car while in IHOP. 2. Come back after over an hour. 3. Won't start and seems drained of battery after only 1-3 tries of starting. 4. Prius is parked on incline and won't start with a jumpstart. 5. Rolled on level surface then jumpstarted...started right up. Any suggestions as to why this maybe happening? Our family is thinking it has to do with sometimes leaving the smart key in the car and sometimes parking on an incline. My dad is suspecting that the 12v battery is bad.
Let sit for 24 hours - check 12v battery (either in trunk or at jumping point). The Toy repair manual says if it less than 11VDC, it will not start, but if you see less than 12.1 VDC, seriously consider replacement ASAP.
BayAreaKid; :welcome: to PRIUSchat. +1 It sounds like it's time for a new 12v battery. Typical service life is 4 years. It's small and once it's been discharged to the point of needing to be jumped the life is reduced. It only has to have enough power to boot some computers. Once the computer are up and running, then then there is lots of 12v coming through the DC to DC converter from the big HV battery. But once it's dead, that's it... nadda. Can't figure out what being on an incline has to do with it though. The car does have fore-aft and side-to-side inclinations sensors, but far as I've heard they are for corrections of the fuel level. Sometimes as the 12v gets weak, the fuel gauge goes whacky and jumps all around, so maybe the computers think there is no fuel. You need to add at least 3 gallons of fuel for it to cancel an out of gas condition. Leaving the fob in the car will run down the 12v battery. The computers know the fob is in the car because there is an antenna under the center console. When the fob is in the car, the computers put the car in a "stand-by to start mode" which uses more 12v power. A message about the transmission can also indicate low 12v power. So all the indicators say that your Pop is right... get thee a new battery. Should go for ~$160 at Toyota, maybe +$50 if they install it. Many folks like a Yellow Top: 12 Volt (12v) Toyota Prius Auxilary Battery with installation kit On sale now for $161. Real good rep, real fast service. :rockon: Be really careful jump staring the car. You've done it a few times so you might be getting too used to it. If you should reverse the leads somehow, you can smoke one or more of the computers, and that means a repair bill ~ $4K. Not good.
If your brother is going to sit in the car w the fob for hours, you can turn off the smartkey system using the switch under the steeringwheel.