My 08 Prius starts sometimes....

If the engine fails to start it will throw many check engine type codes on the dashboard.
It will launch the check engine light and the red red triangle of death. In general the car will be extremely unhappy.

Answer these questions.

Are you getting these codes on the dash?

Have you ever had to jumpstart the car?

Has the dashboard display that has the speedometer on it ever gone to just black?

Btw. Sometimes when you make the car Ready the engine may not come on. Next time this happens
push the gas pedal to the floor and hold it there till the engine starts.

Go on YouTube and search Prius Inspection, it will show you the chicken dance to put the engine in inspection mode where the engine runs continuously for inspection. Fire the engine up let it run for a while and see if it’s having issues. Should run very smoothly it will change rpm level a few times till it warms up.

Btw this is not a salvage title car is it?

 

How old is the 12 volt battery? Sometimes they check out fine, but if they are more than 4 or 5 years old they've been known to cause odd issues in the Prius.

 

I would agree with this except................
I am not really familiar with your model but I don't remember ever driving a Prius......or any other "keyless" model either......where you had to push the "ON" button more than ONCE. I certainly don't have to do that with my C or my Ford.
When the green light first comes on, is that not a "ready" indication ??

P.S. You do know that the gas engine will NOT always start immediately even though the car really IS ready to drive.....using the battery only for a short distance ??

 

That’s extremely odd. The car will throw many codes if engine refuses to start. Those codes will not go away when engine starts they will stay logged until cleared.

That tells me something stupid is happening. The engine is not failing to start it’s not getting the command to start. Also engine start issues are sometimes hybrid battery related as the hybrid battery is used to spin up electrical motor mg2 to start the engine. I would suspect hybrid battery issues if not now but soon given the age of the car.

We see lots of 12 volt battery issues on this site. Next time it starts being stupid do this.
Before starting the car turn on the headlights. Have someone watch the headlights closely. As you push the ready button see if the headlights dim significantly while that happens. It’s basicly a cheap load test.
Headlights should not dim at all during the button push.

I recommend you get an obd device that will harvest codes and more importantly will diagnose hybrid parameters. I like the VXDIAG from amazon.com. You want the model with Toyota techstream software
Last I looked it was $69. The blue one.
Works with a laptop it has the built in obd connector the other end is a usb that plugs into a laptop.

Hundreds of used xp laptops on Craig’s list cheap less than $50. I have one and really like it I also have mini vci but the VXDIAG is easier to set up.

So for less than $150 you can have the same obd decode system the dealer has. If you don’t use it now you will sure need it when the hybrid battery starts failing.

 

Something's odd for sure. I tried this in my wife's '07. I pressed the brake and when I pushed the start button, the car went to ready mode and the light went out on the start button. Ready to go! I then pressed the start button with my foot still on the brake and the car shut off. I tried it again with my foot off the brake and the car shut off.

I can't recreate any scenario in which hitting the start button a second time doesn't shut off the car.

You know what it's starting to sound like as I ponder? I think it's doing what it would do if you did not depress the brake pedal. I'd check the brake lights. You might have a brake light switch that is out of adjustment. It's happened before.

 

welcome!
make sure your stepping on the brake firmly, and then press the go button. you're brake switch might need adjusting, or sometimes, we just get ahead of ourselves

 

LOL! Maybe I should have just said that instead of all the stuff I said before I said that.

 

sorry, my eyes were getting blurry

 

Time to get up and stretch your legs, my friend. In fact, it's time for me to do that, too.

 

That’s what I thought too but her post says she’s holding the brake down and they sure did lots of testing of different things.

Maybe the brake switch is misadjusted and it’s not working right. Need to check if the brake lights are working.

Whatever it is it’s silly.

 

This is an easy one...the car is acting exactly as it should if your foot was off the brake while pressing the start button. MFD on the first press, the rest of the dash (ignition-on mode) after the second press. Turn off on the third.

The ECU is not detecting your foot on the brake pedal. The brake switch is not functioning correctly or you may need to press a bit harder on the brake pedal, or cycle the pedal up and down a bunch of times to try to get the switch to work.....the way the switch is mounted, any normal press of the pedal should be enough to let the plunger release, so maybe a bit of mechanical agitation from releasing the pedal quickly to let it come back up and hit the switch would work better to free it up.......

I was in Myrtle Beach this weekend and on Friday, I took a look at a 2007 that the owner had for sale on CL. Couldn't pass up the chance since it was literally 2 minutes from the resort we were staying at. Said the car wouldn't start and thought it might have a bad HV battery.

Connected techstream, and although it showed a pending P0A80, it also had the brake switch malfunction code, which I showed him. Cycled the pedal a few times and pressed the brake a bit harder, and car fired up just fine. It was probably the cycles that made the switch work. His price was a bit above my high side, so I passed on the deal due to a few other issues I noticed. One of the items I noticed was that the 12v had been disconnected/reconnected to reset codes shortly before I arrived. Kind of removes any little bit of trust I may have had. Didn't even need techstream to see the timers for that one. Just noticed the fuel gauge blinking one dot and then after about 5 minutes it went solid with 4 dots. Pretty positive sign that the battery had been used to reset codes.

The brake switch is normally open. Pressing the brake releases the plunger and the contacts close. Usually. There's always the chance the plunger is sticking, the contacts are sticking or there's just an electrical continuity problem. When the contacts close properly, 12v signal is supplied to the skid control ecu, hybrid vehicle control ecu and power source control ecu, along with completing the current path for the RH, LH and High Mount stop lights/brake lights. Power supplied by the 7.5 amp fuse labelled "STOP".

 

see jerry, i'm not the only senior moment here

 

Yah, but you didn't give us a diagram. Then again, neither did I.

@TMR-JWAP, thanks for the thorough explanation. I seriously admire your thoughtful and knowledgable contributions here.

 

I have the same problem as the original poster and can assure you it is not related to the brake. If you start the car without the brake on, it won't shift out of park. However, in this case, it will shift into neutral. Some more about what happens is when I first press the button the main display doesn't come on. When I press it the second time the main display comes on but will only shift into neutral. Finally, after the first button push, the key fob can be removed and the car will shut off. The other random thing that happens to my car is that sometimes it will start completely but the main display will not light up. The side display does light up, but none of the functions that rely on speed will display.

 

might be a bad combo meter

 

I take back what I wrote above. It is in fact the brake switch. That was my original thought but somehow the one time I tried to just start it without the brake I thought I got different results, but I think I just tried to shift too fast and so nothing happened. When I repeated the test with no brake depressed, it also was able to shift into neutral. So, how difficult is it to replace the brake switch and would I be better just trying to lubricate it? If so, what should I use as a lubricant?