Hi guys long time lurker. First some facts about the car. It’s a 2005 Prius with the premium package so you don’t need the key in the ignition to start. The vehicle has 185,000 miles on it and I recently replaced both the 12 volt battery and put new cells in the traction battery due to the red triangle of death about two months ago. The car was working fine up until about 4 weeks ago when the combination meter began having issues. It went black and I did my research here and now it works for the most part. Every now and then it goes black and after turning the car off and on a few times it comes back. I don’t really mind this issue though. One day though I powered off the car and before I even left the car the mfd came back on. Not thinking much about it I turned it back off. It happened a few more times and I once again chalked it up to just weird electrical issues probably associated with the combination meter. However, last week I turned off the car and as usual waited for it to come back on but it didn’t so I got out and closed the door. I walked away to go into work and my fob would not lock the car. I went back to the car to find it on. It has now done this the last 4-5 times I’ve left the car. I turn the car off. Everything goes black (including the door ajar light and other lights that come on when you turn the car off). Nothing works within the car. You cannot turn it back on and door locks do not work. As soon as I exit and close the door (with the key) the car turns back on. I then turn it off again and it stays off. I have checked the 12v battery charge because the first day this happened the car must’ve been on while I was at work and when I went to lunch it drained enough to the point that it would not start. I trickle charged it to 100% and the battery is being recharged by the car to be kept at 12-14 volts. So I ask anyone. What is causing this and is this just going to get worse? Any suggestions or has anyone else seen this? If you have any questions for me let me know and I will respond as quick as I can.
The 12V 'boots' the electronics when you first push the Start button. The HV battery starts the motor. If your 12V was pulled down too far, you could get all manner of wierdness. I suggest taking it to an auto parts store for a test and a recharge. I bought my Prius with a low 12V batt, and learned the car will not top off the 12V. Instead it will only maintain the charge it already has. I had to replace the 12V, and even the NEW batt came with low voltage (presuming it was stored for long time before being shipped. I purchased a smart charger reconditioned it, and have not had any 12V issues since. Note: There are less expensive smart chargers than the one I purchased. I like that this one not only had a setting for 6 V, but also AGM batteries. I use it for the Prius when the cars sits for a while, as well as re-conditiioning UPS batteries.
i had some similar issues, just wanted to post for posterity my solution the positive battery terminal was loose and connection was intermittent which apparently fooled the electronics. what I did was take the terminal out of the car, take a metal file, and grind down the "lips" where the screw goes through. This made the circumference of the terminal slightly smaller, so that it could grip the post on the battery better. Since I did this and re-installed the terminal, i have not had the phantom restart issue.
The normal course of action is to back off the nut on the terminal clamp so that it is right at the end of the bolt, then use a large screwdriver (or similar) to prise the clamp open nice and wide. This allows the clamp to drop right down to the bottom of the battery terminal. There should be plenty of room now to use the ring end of a box wrench to tighten the clamp all the while holding the clamp firmly down. Your clamps were not standard SAE ones rather than the smaller JIS ones for the stock JIS battery terminal post, by any chance?
Bought my 2009 prius used with 15,000 miles on it. I had an issue where I'd come out and the car would be dead as a doornail. If I tried to get in, then waited like 30 minutes, then tried again, things would work. I did 2 things: - had the dealership completely replace the 12v battery - one of my keyfobs was damaged and I stopped using it That fixed the issue for me, never happened again, has 200,000 miles on it now. do not know if it's related, but, fyi. Probably worth just completely replacing the battery to try to fix it. The dealership told me the battery tested just fine but they didn't have any other ideas and I was like "battery is the only easily replaceable thing it could be just replace it". Like I said the issue went away.
