U0100 and U0293 post NewPriusBattery install

Hello, been lurking the few times I have needed info on problems. Just joined today to be able to post a thread. The background:

2005 Prius owned since new. 3-4 weeks ago got P08A0, P3014, P3015. Torque App showed battery module 4 down 1.5 to 2.0 volts and battery module 5 down about 0.5 volts compared to other modules.

Decided to go with NewPriusBattery install and that was completed 12/27 (yesterday). All went according to plan. First start up no codes, same with second and third trips. All appeared normal on Torque App and car drove wonderfully.

Fourth start up went normal initially, put it in reverse, backed out of parking spot, put it in drive and moved forward about 10 feet and the dash lit up. RTOD, CEL, ABS, PRND flashing, fuel level flashing, ICE was not running and could not turn off anything using the Power button.

I had Torque App running and saw that after the dash lit up, Torque was no longer connected to the ECM.

I spent 10 minutes trying to get it to do something (hold start button for 30 seconds), stab the start button several times in a row, etc. No Go. Tried shutting down Torque and removing dongle and restarting Torque. Same issue, still no communication with ECM.

Tried Start button again and was able to shut it all down. Pushing Start button yielded RTOD still and CEL. Torque was able to connect and got U0100 and U0293 which is generic loss of communication with other command module (U0100) and lost communication with hybrid power train control module (U0293). I cleared those codes and was able to drive home with only RTOD and red car with exclamation point in driver information screen. Car drove normally. No codes stored with Torque App query.

Once home I checked 20A HEV and 15A AM2 fuses, both OK with 12.5V on one side of fuse block. Uncovered enough of hybrid battery to check the 3 low voltage connectors at the battery electronics. All were seated, but unplugged and re-plugged just to be certain. Still RTOD and red car in driver info screen. Still no codes with Torque App.

I know Electronic Modules are in need of a good 12V signal, so checked 12V battery and get 12.4 to 12.6 at the battery. I noticed the module on the positive terminal could be twisted slightly, so decided to re-seat and tighten. I knew this would reset all the ECM and control modules. So, now no codes, no warnings, nothing, all functioned properly so took it on a 20 minute drive. No issues. Stopped for gas, hit the Start button, drove to the driveway of the gas station and when I started to pull into traffic, I got the full dash of lights again. Coasted to a safe spot out of traffic. Again, I get RTOD, CEL, ABS, PRND flashing, fuel level flashing, ICE was not running and could not turn off anything using the Power button.

So, I went and pulled the negative battery terminal for a minute, put it back and got everything normal to drive home.

Looking for some guidance and ideas from those here with more extensive knowledge than me. I know I should get a scan with a Prius dedicated tool as opposed to the Torque App, but that also may not work since there is no communication with the ECM when the dash is lit up. Thanks in advance and sorry for the chapter. Just figured it would be best to include as much background as possible.

 

Excellent, Thank you for your reply. I just performed the load test as described. It was 12.70V at the fuse/relay box after driving and letting sit for 5 minutes. I then turned on the headlights for 5 minutes, turned them off for 1 minute, the re-measured at the fuse /relay box and got 12.55V. So, not horrible. Will continue to monitor and will start looking for replacement. Currently running Optima Yellow Top, but it is at least 4 years old.

I also did some more searching here and elsewhere and found one thread on Prius Chat that stated their OBD II dongle was causing control module communication issues and also found one other instance of same not on Prius Chat.

I just pulled my ELM 327 OBD II Bluetooth dongle and fired her up and went for an hour drive. I stopped 6-7 times after pulling in to a parking lot and shut it off and walked away with the key enough to get out range for a few minutes and then came back and fired her up. No codes, no issues, car drove beautifully.

I will continue to monitor and report back as things progress. I hate when people do not close out threads with updated information for future users.

 

In my first post, after the first time I got all the codes/lights, I did mention that the positive terminal of the 12V battery could be moved if I pushed on the big red and black plastic parts connected to the positive terminal. I did loosen and re-seat the positive terminal at that time and that re-set all the control modules. No corrosion whatsoever on pos/neg terminals or body ground. No looseness on neg terminal or body ground at that time, no corrosion on neg terminal or body ground either.

The car did exhibit all the codes/lights again a second time after the above. This time I pulled the negative terminal to re-set the control modules. The only other variable changed since the second occurrence of the lights/codes is removing the OBD II dongle.

So, since battery negative and body ground showed no issues, the current most likely culprit is the OBD II dongle interfering with module communication. Car has driven perfectly since removing dongle (an hour of driving with 6-7 stops/starts). Will drive more today.

No evidence of any rodent incursion, but I have not yet pulled the glove box to inspect Hybrid Vehicle Control ECU or ECM wiring. I am going to wait until I get additional codes/lights.

 

It has been a week with the OBD II dongle removed and no issues. I think I can pretty conclusively say that was the cause of the codes.

Both times it happened, it was shortly after starting up the car and likely while the dongle and Torque App were trying to re-establish communication with the ECU. That process of re-establishing communication is when the ECU probably determined it was not able to communicate with the hybrid control module and barfed up all the codes and put itself in limp mode.

The dongle is an ELM 327 Mini purchased from EBAY. It works fine with my other cars and worked fine with the Prius on several occasions. There must be some situation with start up and the ECM establishing communications with other control modules simultaneously with the dongle establishing communications with the ECM.

If anything changes, I will update.