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!