hal9000 Posted December 12, 2022 Share Posted December 12, 2022 I posted this to the ffh specific forum and didn't get any response. Hopefully someone here can help... A few mornings ago, my ffh shut down as I approached an intersection and wouldn't restart, at least not enough immediately. The cluster would light up with all the engine and drivetrain warnings, but that's it. So I flipped on the hazards and got out to check. Along with no drivetrain power, the hazards weren't working (dash indicator was working and the lights on the mirrors were blinking, but no corner flashers). I did a little poking and prodding under the hood and shortly after lightly tugging a few of the harnesses I noticed the hazards had come on (I don't believe the movement of the harness was related to the lights coming on at this point, but could be wrong) so I tried the key again and the car started and ran normally.... Trying to get it sorted before the next family road trip and any advice is appreciated. Here's what I know for sure. It was 15F when the shutdown occurred. And the car had driven ~1 mi since a cold start after being outside overnight. The 12v battery is about 4y old and today a battery test showed it "is good but needs a charge. The alternator is working properly. The hybrid battery was over half charged when the shutdown occurred. The day before, I got an error on the Right side dash screen that said it had "temporarily lost contact with touch screen" (I don't believe the car has a touch screen anywhere).... Any ideas on where to look next? I suspect the battery but am not sure yet. 0 Quote Link to comment Share on other sites More sharing options...
dogo88 Posted December 12, 2022 Share Posted December 12, 2022 In all the posts I've read on these forums, with the symptoms you are having, the recommendation is almost always to change the 12v battery. It's the easiest, cheapest and quickest option. It's old enough to be questionable and as you indicated, it's needs a charge, all indicators of a needed replacement. When my 2010 started to act weird I replaced mine. My 2019 is 4 years old but is not showing any issues, yet. 0 Quote Link to comment Share on other sites More sharing options...
Waldo Posted December 12, 2022 Share Posted December 12, 2022 I agree, seems quite probable that it's a 12V battery issue. 0 Quote Link to comment Share on other sites More sharing options...
hal9000 Posted December 12, 2022 Author Share Posted December 12, 2022 Thanks for the confirmation. I haven't had the car for long and was initially worried about a hidden intermittent issue. The battery is still looking like the most common culprit though. With no codes or anything that's where I'm starting.... On a related note, does anyone know if the Regen braking also charges the 12v battery? 0 Quote Link to comment Share on other sites More sharing options...
Waldo Posted December 12, 2022 Share Posted December 12, 2022 (edited) 9 minutes ago, hal9000 said: On a related note, does anyone know if the Regen braking also charges the 12v battery? No, the regen energy only goes straight into the HV battery. The 12v battery is then charged from the HV battery via the DC/DC inverter that's part of the HV battery pack in the trunk. There is no alternator. Edited December 12, 2022 by Waldo 0 Quote Link to comment Share on other sites More sharing options...
hal9000 Posted December 12, 2022 Author Share Posted December 12, 2022 That's elegant. Thanks for the info. I really need to find time to learn more about this car. 0 Quote Link to comment Share on other sites More sharing options...
Waldo Posted December 12, 2022 Share Posted December 12, 2022 If you want to learn about how the hybrid system works, you can study the Prius, it really is fundamentally the same. But there's likely a lot more info out there related to the Prius. 0 Quote Link to comment Share on other sites More sharing options...
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