Help...Code u0293...

First thing I would try is unplugging the negative on the battery for one minute and then reconnecting to reset everything. If the car does restart, drive carefully to see if error reoccurs. Based on this:https://techinfo.toyota.com/t3Portal/document/rm/RM1290U/xhtml/RM000003VFG006X.html?sisuffix=ff&locale=en&siid=1468434074526
it sounds like it's either a problem with the cables connecting to the Power Management Control ECU or the PMCECU itself has given up. Have you tried following the 3 steps at the bottom of that page? If something open-circuited or close-circuited that shouldn't have, that could have caused the error you're getting. Sometimes such errors have to be tracked down by testing each wire in a harness to see if it's open or connected to ground or the other end of the cable as expected.

 

Hey Kevin I know it has been years but as we speak I’m having this same problem how do I check wire cables to see if it has a complete ground?

 

You might look at this post for a little more info on troubleshooting a U0293. Like the other commUnication codes, there are two ECUs involved: the one U0293 is 'about', and the one that reported the code. Those are the two having trouble communicating with each other. Some scan tools make it easy and some make it hard to see which ECU reported the code.

"Reseal power inverter" are three words I've never seen next to each other in anything about a U0293 code. I would trust the troubleshooting steps in the repair manual more.

Toyota Service Information and Where To Find It | PriusChat

 

Can you write in detail what happened to the car?
Is it possible to scan error codes?

 

Thank you very much for replying! so my skid control ecu could be the issue huh?… where is that exactly in the Gen 2? You know I don’t know if this is significant too; at times when I hold the brake button during start up it makes a loud buzzing sound and the interior lights would get slightly dim is this related to the skid control (braking) ecu?

 

I don't know what you mean by "hold the brake button".

The buzzing sound could be the electric pump that maintains the brake fluid pressure for you. That's its job. It can use enough electricity to dim the lights a little.

I can't tell if you read the linked post about U0293. The U codes are all communication codes. There's one ECU that is reporting the code, and there's another ECU that the code refers to, and those are the two things having trouble communicating with each other. I would not recommend guessing, but instead using the information from a scan tool to know which devices are not communicating with each other.

Once you know that, there are troubleshooting steps to find the wiring problem or whatever other issue might be stopping those two things from communicating.

 

Thank you for replying and yes I will:

for about 2 years now I’ve had start up issues with an error code U0293 it would be an issue where the car would start after many times attempting it to get into ready mode and other times won’t start at all with the cluster dash lights flashing with the orange vsc, tire pressure, etc lights on. At times while I’m driving, the car would randomly stall just like earlier post when I either get into gas mode (if you will) from electric idling, or accelerate after hitting the brakes. This crap happened after stop lights smh.

I’ve now switched out 2 Hybrid ECUs from original: first one 2 years ago that crapped out due to a cascade of electric problems i got from my car being jumped from battery (I know now… a cardinal sin to the Prius) where I had to replace many electrical components like the fusable link and inverter converter. After 3 weeks when I got the ECU replaced is when I started having the ready mode issues U0293. I dealt with it because it seemed minor, most of the time it would start, hell to the point the check engine light would go away. Then it wouldn't start at all over the summer which is when I got my 2nd ECU back in June replaced and installed myself. It was working fine up until 2 weeks ago displaying the same symptoms as previously mentioned. This is when I posted here.

Also to mention I did do some electrical test to see if there’s a short in my wire harness CAN bus lines using the obd pins 4 to 6 and 4 to 14 respectively. My multimeter only displays some resistance in the 20k ranges I don’t know if that’s significant or not but I’m assuming it’s a module in my car could be causing this. Perhaps what I just read from Chapman linked post the skid control ecu?… don’t know yet but just wanted to let you know, any suggestions please let me know.

 

I meant to say brake pedal not button, and yes I read the post where you linked “this post” about the U0293 and you said that there are three modules that communicate with the HV ECU, the battery ecu, engine ECU which is right next to the hv ECU, and skid control ecu.

As far as my scan too it says “lost communication to hybrid vehicle control system” no other detail besides that. Are you referring to something other scan tool that’ll provide more detail?

I did look at my battery ecu next to the hybrid battery and didn’t notice anything off, corroded or burnt, even opened up the board and looks completely normal.

the engine ecu from my understanding if have issues the car wouldn’t start at all is this the case? I don’t know how to test to know for sure

the last thing for sure is the brake ecu I have not checked or access at all.

Edit: I did forget another code did pop up when I replaced Hybrid ECU a second time, it was U0100 lost communication with ecm. The check engine light would go away while I was driving and gas engine would run but if I’m 30 mph or under with electric the engine light would pop up with this code.

 

When the scan tool asks the ECUs in the car "anybody have any trouble codes?", some scan tools will group whatever trouble codes come back according to which ECU reported them, and some other scan tools just jumble all the codes together like "all these codes got reported by somebody".

This thread reviewed a bunch of tools/apps and I think mentioned which ones give the more useful display. I think Car Scanner was one. (And always Techstream, of course.)

Gen2 OBD2 app review | PriusChat

It is especially important where U codes are involved, because they always involve something that can't communicate with something else, and the code only identifies one of them, and the other is the one that gave the code.

After knowing which two things aren't communicating, it's not necessarily that either one of them is broken; there could be a problem in the communication wiring between them, for example.

 

Ah ok let me make sure I understand. The communication codes could indicate a wiring issue or a module issue and in order to find that info I need like a particular scan tool and app like techstream?

 

So, the easiest way to find the reason Thing A and Thing B in the car can't communicate with each other is, first, find out what Thing A is and what Thing B is, and use the repair manual and wiring diagram to see where the communication wires between Thing A and Thing B go, and then do some troubleshooting to see if the problem is with the wires or what.

We already know what Thing B is: it's the HV control ECU (the U0293 code tells us that). Thing A is whatever ECU in the car gave the U0293 code.

There are scan tools and apps that make it easy to see what Thing A is (not just one particular choice, just any one that shows which ECU each code comes from), and there are other scan tools and apps that don't show you that, so they make it hard.

Not saying it would be flat-out impossible to troubleshoot the problem without the make-it-easy kind of scan tool; you'd just be working harder and spending more time on trial and error and maybe the parts cannon.

 

It can be useful to know which ecu is setting the U0293. There are some wires that go to one ecu but not others. That could help narrow down pontential problem areas.

So Techstream is one option, but there are some others in the linked thread that can scan all systems in your Prius

That said, you can backprobe circuits at the hybrid control ecu. In order to work properly, the ecu needs: power (battery + & ignition +), ground, and communication lines.

When the car is "ready", CANhi should be around 2.7V, CANlo should be around 2.3V.

Time for the wiring diagrams.

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Ah ok I see what you’re saying I actually have the wire diagram, so am I looking g for a shorted wire when I back probe each wire on the hv ecu and should I do this while the car is ready mode? If I can get it into ready mode lol?

 

I would wait until I knew which other ECU in the car is the one saying it can't communicate with the HV ECU. Some scan tools make that an easy question.

Once I knew that, I'd use the wiring diagram to find out which wires make up the communication circuit between those two ECUs. Those specific wires would be where I would focus my testing.

I'd probably arrange my testing a lot like whatever is suggested in the "multiplex communication" section of the repair manual, for communication problems between those two ECUs.

 

Are these wire diagrams sufficient enough. I received it from my mechanic at the shop that said it’s my ECM causing the issues. If so I don’t really understand how to read it for instance where the hybrid vehicle control ECU on upper left side of page is what does TC mean? the numbers 6,9,8 or the cylinder shape object that has NCA what does this indicate?

 

Wanted to correct earlier Infoi gave:

ive actually did replace the hybrid control ecu 2 years ago and now will be replacing my ECM for the second time, i said previously three times I’ve replaced my hybrid ecu that’s actually incorrect!

One time 2 years ago I replaced the hybrid vehicle control ecu then 3 weeks is when I started experiencing the electronic issues finally got my ecm replaced back in June and now am going through a warranty exchange from the company for my second one from what my mechanic told me. Hope this provides better context to my situation.
Got mixed up due them being next to each other smh