I've got a 2008 RX400H, 220k miles.

Driving fine until Wednesday it effectively shut down on me on the highway...."check hybrid system, VCU, malfunction" etc all lit up on dashboard. Car cruised to a stop. I could restart it only once on battery to move into parking spot. Towed to Toyota dealership....Lexus wouldn't take it since I haven't serviced it there.

Service manager said $2875 to replace HV Control ECU module.
Said codes pointed to that and "pretty sure" that would fix it but no guarantee. Seems like a leap of faith at $3k dollars for something that may not fix the issue.
I asked for problem codes and they provided following:
P3000-388
P0335
P3000
Comments: Technician "tested for resistance between crankshaft position sensor and computer. Found less than 1"

Does any of this add up for you all? Any ideas if these codes seem to align with HV ECU module? I can't find it by googling.

 

I got a P3000-388 once when I unexpectedly ran out of gas!

But seriously, yes, a PO355 could be the result of a bad ECU.

Ask them if they performed all of the trouble shooting tests in the Repair Manual and the attached Technical bulletin?

It could also be the sensor installation, damaged sensor plate, or loose camshaft.

-M

 

I do foreign machine diagnostics and electronic repair for my job and I can't stress enough how important it is to have good working parts for spares.
A car is just like the machines I work on so I have a spare ecm and body ecu and etc for my car because it's so much easier to diagnose complex problems like this with a good unit to swap in for testing.

Used Ecm's can be bought on fleabay for our cars dirt cheap and is a huge help and time saver for situations like this.
Then there is no guessing.

Otherwise, much more work and testing needs to be done the hard way and we don't really know what the dealer checked or didn't check.
A scanner plugged in while driving could help so data can be monitored and give clues- MAF, engine temp, rpms, fuel trims, etc watching for anomolies while driving.

 

+1
When my hybrid battery was dying, I stopped at Toyota dealer, told them that I had an error code, that I cleaned it and asked the to test the battery. Car was there for several hours, and then they told me that battery is OK. Several days later, when I was traveling, I got the error again (Hybrid system went into safe mode + "Christmas tree" on dashboard). I visited dealer again and found out that they just connect the scanner and didn't find any error code. Battery were not tested at all.

 

I am dealing with same issue. I replaced 12v battery and the HV control ECU died. Dealership says I need new hv control ecu and that used one will not work. What did you end up doing? I am not wanting to spend 3000+ at the stealership on somethingbthat might or might not fix the problem.

 

​​​​​​With the high mileage on the car, I ended up selling for a reasonable price and foregoing to the repair. My biggest concern was the mechanic wasn't able to guarantee that this would fix the issue. Wasn't worth the risk to me. Had a buyer will to take it "as is"

Good luck