Won't start with good 12V battery

I am helping a fellow Prius owner troubleshoot his 2007 Prius with about 220K miles, which is now stranded in a Subway parking lot in danger of being towed.

Some background:

I helped him find this car, and when test driving the car, out of habit, I inserted the key in the dash and hit the power button. I do this in my car since my remote panic button is touchy, so the battery is removed. In this 2007, nothing happened. The dealer then tried it with the key simply sitting in the cup holder, and it started fine. So something is awry with the dash slot. But it has worked fine using the remote key for several months.

The 12 V battery went out about 2 weeks ago, which was several years old. We replaced it with a new battery, which should be good. The connections to this have been checked and seem tight.

One time about two start-ups after we replaced the 12V battery, he hit the Power button, and the car took about 10 seconds to light up the dash, but it did eventually start up. Subsequent attempts were successful.

Current situation:

After driving to a Subway, he got back in the car minutes later, put his foot on the brake and hit the Power button. Nothing happened other than the light on the Power button turned green. With his foot on the brake, he tried pressing the Power button again, and the following happened:
-- The light on the Power button then turned orange.
-- The Check Engine Light came on.
-- No other light other than the CEL came on. No clock, No center display.
-- The car made normal start-up noises, and the brake pedal pushed out and got very firm.
-- The red security system light on the dash remained blinking the entire time as though the key were not being recognized. He tried inserting the key in the slot, which made that red flashing light turn off, but that did not allow the car to start or do anything different than what I described above.

Upon pressing the Power button a third time, the car turned off and the CEL went out.

We suspected that the fob was not being recognized, so he found a place that sells watch batteries and replaced the CR2032 in the remote. He tried multiple batteries, all with no improvement. Both prior to and after replacing the battery, the buttons on the remote worked fine to lock and unlock the doors and the headlights would illuminate when doing so.

He also tried putting a little gas in the car just in case it was out of gas. No difference.

I asked him if it is possible he hit the Key button under the steering wheel. He said it's not impossible, but he doesn't think so.

I've read that the slot not working can simply be from a misaligned antenna. I never felt very motivated to fix it though since replacing the battery in the remote should obviate the need for the slot. I am slightly puzzled though that the red flashing light turns off while the key is in the slot, but doesn't allow the car to start, and didn't even prior to this. I'm not sure what talks to what in the process of starting up.

I am about a two hour drive from the car, so would like to have a lot of knowledge before going there. I intend to go there and check the 12V battery, try hitting that Key button, perhaps take apart the dash to check the alignment of the antenna in the slot (I have done my combo display fix, so I know how the dash comes apart.) and try resetting the key by holding down both lock and unlock at the same time. I don't have much confidence in any of those things though. So, any wisdom or research topic suggestions would be very appreciated.

Have a good one,
Bill

 

I don't think gas has anything to do with it. I have run out of gas, and in situation, the engine still tries to start for about 10 seconds and the dash will illuminate, but won't let you go into gear. This car won't even light up the dash except the CEL.

I have a decent multimeter I intend to bring. However, other than checking the 12 V battery for 12.5 V, I'm not sure what else to check.

I have a bluetooth OBDII reader that I use with various apps on my phone. I am not convinced it is powering up enough for that to work, but it's worth a try.

In the time since I made the original post, I have done more research and I suspect that the reason the fob doesn't work in the slot is that the RFID chip is missing in the sole remote. The case looks to be in much better condition than mine, so likely has been swapped by someone unaware that the RFID chip needed to go with the circuit board, and since the fob works fine without it until the battery dies, they never realized their mistake.

 

We actually just fixed the Combination Meter (the speedometer, shift indicator, etc...) a few months ago by removing it and having a guy on ebay replace the diodes. Has worked fine since then. Although, now that I think about it, if the lights didn't light up like he would have been expecting, he could have gotten faked out by the lack of lights and thought it wouldn't work, but all he needed to do was put it in gear. HOWEVER, I doubt this is the case since the engine itself never started or even tried to start. Also, the brake pedal getting really firm isn't normal.

Edit: I also just realized that if the Combination Meter were out, it would still power up the center display, which is not happening.

2nd Edit: If the SKS button were switched off, would it even turn on the CEL? I would think it wouldn't go this far. Although now that I say this, it makes me realize that the car is actually at least partly booting up, so perhaps an OBDII reader could tell me something.

I do really appreciate all the input even though I keep shooting down ideas.

Bill

 

Current troubleshooting strategy:

- Check the 12V battery
- Try hitting the Key button (not putting a lot of confidence in this since the CEL illuminates.)
- USE OBDII reader to see if any codes tell me what is awry
- Try resetting the key by holding down both lock and unlock at the same time. (my wife saw this as a way of resetting the key, but I am not putting much confidence in it.)
- Disconnect the battery for a few minutes, reconnect, cross fingers, etc...

It appears that if I lost the RFID chip, as both JC91006 and I suspect, there is no way of replacing the chip since there is not an old one to get any info off of.

 

I have driven for months with a bad combination meter, and the owner of this car has too, and in both cars, the center display worked even when the Combination Meter didn't illuminate. Well, at least it worked in the sense of illuminating and operating the HVAC and stereo. It didn't do the fuel consumption stuff since it was not getting data from the Combo Meter.

 

Ooh. Definitely going to go read up on the inverter pump issue and the AMS fuse. I am not convinced that there aren't codes. I had previously thought that the car wasn't powering up enough to get codes, but I now think that is a flawed assumption since the CEL illuminates.

Thank you JC91006!

 

So i am at the car and have updates.

When I got to the car with the smart key, pressing the buttons on the fob would not unlock the door. I used the metal key inside the fob to unlock the door. I then hit the Key button under the steering wheel. At that point, nothing worked. I pressed the Power button and i was able to repeat what the owner told me with one notable exception. When i pressed the button it would just turn green, but the flashing red SKS icon did go off, as it should. He had said the flashing red car with the key stayed flashing after the button was pressed. Sorry about that red herring. When i pressed Power again, the CEL came on, the red SKS icon stayed off, the coolant pump could be heard going (darn) and i heard the relays click. They sounded weak though. The windows do not operate, so I think the car is only in Accessories mode.

The power lock buttons on the door panels do not work regardless of if the car is on. The gear shift does not put the car into any gear or cause any beeps.

I popped the hood and confirmed that there was coolant flowing in the inverter reservoir by removing the cap and witnessing turbulence. I could also feel the vibration.

I got in and hit the power button again, which turned it off, but there was no click of relays. I think on startup the relays tried to click shut, but just made a poor attempt and never shut.

So i checked the 12 V, which is at 12.40V. I put clamp leads on it while i hit the power button twice. The voltage never dipped at all. It remained at 12.40V. I think that voltage corresponds to about 55% SOC, which should be enough i would think. Wouldn't closing that relay cause some sort of voltage drop? Is it possible it is just a dirty connection in the 12 V system?

I tried shutting the door and locking it with the fob. Still no luck.

The rear hatch will not open.

I tried reading codes with my OBDII reader, but it never gets power since i am not getting past Accessory mode.

I hesitate to disconnect the battery since i then lose codes, but since i can't get the reader to power up, that seems moot.

Thoughts?

 

I just tried similar things in my prius. I hooked the multimeter leads to the 12 V as i powered up and the voltage did not drop. It stayed at a steady 12.47 V.

If i hit my power button without pressing the brake, which puts the car in accessory mode, it will power up the center display and clock, neither of which are powering up on the ailing car at any time.

 

Pressing on the brake pedal doesn't cause the brake lights to turn on.

Does that mean domething?

 

Wow. I could definitely believe that that is it. Thank you so much for the suggestion

I just finished swapping batteries between my car and the dead car. My earlier report that the voltages didn't drop was false. To see the display in yhe dim light i activated the backlight, which on my multimeterninvolves holding down the Hold button, which I did wrong and froze the display.

When i did it again, my battery dropped down to 12.05 V then rebounded to 13.xx when the relays clicked shut. The ailing car dropped to 11.7 then came up to 12.20. So i swapped batteries, and as feared, my battery did not make his car work, and his battery was able to make my car work fine. So, his car is still borken. But i am now going to check out the brake light switch.

Thank you everyone for all the ideas.

Bill

 

Actually i just checked in my car, and if i leave my foot off the brake and hit the button once it goes into accessory mode, which doesn't light up the dash, but Does turn on the center display AND the clock. Neither of those come on on my friend's car. Then if i hit it again, my dash lights up and looks totally normal except it doesn't say "Ready" whereas in his car, all i get is a CEL.

I noticed that when i push on the pedal, it does the normal clicking noise of building pressure in the pedal.

Is there some major fuse or relay that would cut power to the power locking system, brakes and dash?

 

think i found something. There is a broken bit of bus bar in the under hood fuse panel. It looks like there is a crimped section on the outboard bar near the top where i joins to the positive jump block.

 

think i found something. There is a broken bit of bus bar in the under hood fuse panel. It looks like there is a crimped section on the outboard bar near the top where i joins to the positive jump block.