Hi all, Hope you guys are all doing well and enjoying the weekend. My Prius gen 3 2105 unlocks and locks with both key fobs but the red padlock and car sign is still flashing on the dashboard. Car will not start. Nothing happens when I press the start button even after holding the key next to it and pressing the brake. The usual noise appears which you get whenever you press the brake (something electronic happening). I've opened up the centre console and even put the key next to what I think is the receiver (brown rectangle thing). Can't even communicate with OBD2 and I've checked the OBS fuse among many others. Changed both key fob batteries and 12v battery is fine. Even hooked up jump cables to make sure 12v was not dying. At complete loss here. Any ideas or anyone had the same problem?
Checked the voltage ⚡, it is 12.3v but when I had the jump leads in it rose to 13.something. will check for wire damage next. Thanks
12.3v is very low, for the Prius. 12.6 is the lowest before issues start showing up. I know it doesn't seem like .3 volts matters, but it does for the Prius. How old is the battery? At the least charge it with an AGM charger, 5 amps or less for at least 4 hours then let it sit for 10 minutes after removing it. Then measure the voltage....
So next update: No visual damage to any of the wires on the loom. However, I put on the jump leads from my Mazda to the front of the Prius (engine bay), checked the voltage on aux battery and no change i.e. it remained at 12.36. Put the jump leads in directly onto the aux battery and voltage jumped to 13.68 - both times with jump leads on. Clearly the current is not travelling from front to the back at the battery. Does this give us some indication as to where I should be looking? A specific fuse or specific wires? Is this related at all to the key not being detected? Just to mention again that the key still locks and unlocks the car as it should, with buttons.
honestly, it could be a lot of things. partially working key fob was a symptom of a low 12v on an older prius i had. is there anywhere that you can get it load tested? we have free ones at auto parts stores
In England, not sure if we have them. But I try. Maybe I'll look into a wiring diagram to see which wires connect the front to the back and go from there. Will let everyone know if I find a solution. Hate it when threads end without problem solved/shared.
Yeah, there was no change at the back, in voltage, at all when the jump leads were on the front. I put the jump leads on the back, directly on the battery and hey presto the voltage jumped up to 13.68v. clearly there is a break in the circuit from front to back, hence no dashboard coming on or start button working. I just need to identify which wires to investigate, as I'm not too sure at the moment. Might ask a Toyota dealer or get a wiring diagram from somewhere. If only diagnosedan lived locally
Will try and run a wire directly from front positive to rear, at the 12v battery and maybe get a ground too for good measure. See if that works. 01:49 here, so it will wait till tomorrow evening.
No cigar! Wired from front to back and no change in any symptoms. I remember this happening once before but the car randomly came back to life. This time completely gone. Oh well. I will keep digging.
That would have been some useful info early on...... It's likely you have a loose connection somewhere. Probably in the fuse box.
So if you put the jump from the Mazda on the UHJP (under hood jump point), then the UHJP will be 13.68V and the battery will be 12.3V? If you put the jump from the Mazda directly on the battery the battery is 13.68V and the UHJP is what? With no jump both UHJP and battery are both 12.3V? It seems odd to me, like maybe a measurement error. I'd think you'd get a response from the vehicle in one of those scenarios. Have you double checked that the ground from the battery is well connected to the chassis? I would also check for 12v at the OBD2 connector (pin 16 should be 12v even when car is off, use pin 4 or 5 as ground) just for the heck of it. I’d also play around with the power button by say, pressing it repeatedly or smacking it. You say no visible wiring damage but is there any signs of rodents whatsoever?
No rodent signs but you make good suggestions. Will try all tomorrow and also give you definitives on the voltages.
