Warning lights all over, and wacky readings from my code reader

Hello, all. One of the three prii in my fleet is being a bit of a problem child.

2009 model, basically stole it from a guy for $1500. 158k miles.

Currently getting the Red Triangle, “BRAKE”, ABS, VSC, and ( ! ).

Codes include U1029 (lost comms with brake system control module), U0073 (control module communication bus off) U0123, U0124, U0126 (lost comms with yaw rate/lateral acceleration/steering angle sensors, respectively) and other similar indications. I also got C1310 at one point, and was checking the inverter cooling system (no visible leaks, plenty of fluid, good turbulence in the tank so the pumps ok) when I noticed the crazy traces on the inverter temps and B+ voltage levels on my code reader while driving around the block at about 25mph. See the attached image for reference. Pretty sure the inverter wasn’t heating and cooling itself between 150° and 0° in an instant like that, so obviously a garbage reading.

To me, this all points to a crappy connector somewhere. The question is, WHERE? Can anyone point me in the right direction?

I am suspicious of the brake power module under the trunk. My daughter left a leaking jug of coolant in the trunk and I just had to drain about 1.5” of coolant from under/around the battery last week.

I’m not afraid to dig into this thing, and I’m pretty OK with hand tools. I’ve already pulled the dash apart and fixed the bum cap on the dash display board on this car. Don’t be afraid to use technical jargon. Hit me with whatever you’ve got.

 

Would this also cause the wacky readings from the cooling system, or is there a possibility of there being multiple issues here? I mean, that’s always a possibility I suppose, but could a bad connection somewhere else cause both symptom sets at the same time or is this definitely just at that one computer?

You underestimate my power, Obi-Wan! You should see some of the spaces I have to get in and out of at work on a daily basis. It’s a wonder I don’t have back and neck issues (yet).

 

Did that. Replaced with a new yellow top as well. All connections are solid.

 

Just to be clear, you’re taking about the main ECU (green highlight) and the three nuts on firewall studs, including the one in a nice cozy spot up top (red highlights), correct?

 

Hmm. I’ll need to make sure my diagnostic rig can rewrite the VIN, reset the immobilizer, and whatever else needs to happen there. I’m pretty sure it’ll do the VIN reprogram, but I’ll have to check on the other items. You mentioned calibrating something as well?

What about these guys? They claim they’ll preprogram your VIN for you and send you an immobilizer hack tool as well to make it “plug and play”for $179. Might be worth it versus me smoke-checking an ECU trying to figure out the ins and outs of reprogramming it.

2009 Toyota Prius 1.5L - ECM ECU PCM | 89661-47250 | Flagship One

 

Glad I asked.

Nope, I’ve got a Zurich ZRPRO tablet. It’s pretty capable, but there’s not a lot of info in the manual, and a lot of chingrish in the menus

I found this: but that’s it so far.

 

Maybe it can zero those after all...

 

12.78v across the lugs. Cleaned the terminals. Solid 12.76v at the power socket up front, indicating good ground and power in acc mode, with nominal voltage drop.

 

I’ll look into it tonight and see what it’s got. I seem to remember something that looked like that, I’ll double check when I get home. This ZRPRO computer is actually pretty surprisingly decent for a Harbor Freight tool.

 

Yep! It can do that too.

 

So, a neat thing happened after resetting the existing “bad” skid computer and doing the zero procedure on everything as a practice run before buying a skid computer and using the diagnostic tablet “in anger” with it.

Nothing. As in no more errors. No more warning lights. We’ve driven the hell out of it for two days, over 150 miles, no trouble.

I can only assume here was some kind of calibration memory issue. At this point, I’m still considering buying a skid computer just because memory cell failures don’t just go away. (case in point: Tesla’s recent woes with their MCU’s) But for now... :shrug: