long beep, red triangle, "problem", can't reach Ready mode

My son was driving my 2004 2nd gen Prius. As he was slowing down to turn there was a long beep, the red triangle appears, the screen says "problem", and the car was thrown into neutral and became unresponsive. Now the car will not boot into ready mode. When you try, the display flashes like it wants to boot up, I hear a series of relay clicks and then nothing. I can get it come up in the accessory mode (radio plays etc...). Since I cannot get it to ready mode, I cannot access the codes with the TechStream software.

I have made sure the aux battery is fully charged working properly. I have checked the oil level and gas cap (saw a few posts about this). It did recently rain and the car was outside if this helps.

I am clueless on how to proceed. Without being able to access the ECU codes what can be done to diagnose the problem? Thanks for your input.

Additional info: The car has about 195K on it and the main battery has not been replaced. There was also strange odor when I got in the car (my son came in to get me immediately after the incident). It was hard to tell if it was hot electronics or the pulled pork my wife was transporting at the time in a crock pot

 

Thank you for your response. Without pushing the brake pedal: Once: in aux mode and MFD lights up, can play radio, etc.. Twice: car tries to kick into Ready mode but fails. Display flashes briefly and a series of relay clicks can be hear. Whether once or twice, the power button light flashes amber.

 

Yes! AM2 fuse is blown. But fuses blow for a reason. Any ideas. Thanks so much!

 

Patrick: Pressing the power button twice results in a temporary flash on the display and some relay clicks then nothing -- totally dead display. For either state I try to put it in, the TechStream software gives the error: "A communication error with Engine ECU occurred. Please confirm the Engine ECU is properly installed."

We now know I have a blown AM2 fuse (thanks JC91006). Now to find out why.

 

Perhaps I am confusing the sequence. My apologies. Foot off brake 1st push works and car goes into accessory mode, second push nothing (display briefly flashes and a series of relay clicks can be heard and then nothing). We now know I have a blown AM2 fuse (thanks JC91006). Now to find out why.

 

Hi John: The car never reaches the IG-ON mode so I cannot get the codes. We now know I have a blown AM2 fuse (thanks JC91006). Now to find out why. I will check the inverter coolant and pump (the inverter pump was replaced a number of years ago on a recall). Thank you.

 

TMR-JWAP: I will check the inverter pump. Perhaps I can bridge the AM2 fuse and unplug the inverter pump (in case it is shorted) to see if the car will go IG-ON mode so I can retrieve the error codes? I am always very nervous about by-passing a fuse because they blow for a reason. Does this sound like a thing to do?

 

TMR-JWAP: Thanks. I will need to run up to the auto parts store to buy a fuse. I will get back to everyone with the out come.

 

I pulled the plug from the inverter coolant pump, replaced the AM2 fuse, and the car was able to boot into IG-ON mode. I collected the codes via the TechStream and here they are:

• Hybrid Control: P0A1D and P3102
• ABS/VSC/TRC: C1242
• Immobiliser: B2795
• Gateway: B1260 and B1271

I still need to look these up. (We have company over at the moment for Mother's day and my wife is not happy I disappeared). Does anyone see anything in the codes that might indicate that it is not the inverter pump? Thanks so much!

Note that I have already replaced the inverter pump under the recall a number of years ago. Are failures of these pumps common?

 

Patrick: Great advice on isolating the problem. Thank you! Question: Is it better to disconnect the battery to clear the codes or to clear the codes via the TechStream SW?