2007 Prius - Code U0293 during smog

Very strange.
Did you try a different smog shop?
I know that the in California there are at least two different types of data link adapters to get data for the smog equipment. Maybe find out what data link the one shop was using and go to another shop with a different type.
The code that you have is lost communication with the HV computer. Maybe you have a bad computer in the battery. (This is the location of the HV computer) Or your computer has corrosion very common on Gen 2.

 

Or there could be nothing at all wrong with the car. It could be that the testing station's smog check machine is causing the Uxxxx code by failing to communicate correctly. There have been more than a few posts in the past where (cheap) devices (i. e. BlueTooth OBDII readers) that were the cause of the communication errors.

As mentioned above try another checking facility.

 

See my posting in an older thread about a very similar symptom, which turned out to be a problem in the DLC3 (OBD II) connector itself.

The trouble could be anywhere on the CAN bus, but the report says DTC U0293, Lost Communication with HV ECU, was stored by ECU 7E0, the engine control module (ECM), not by the battery ECU.

The HV ECU is in the instrument panel, next to the ECM; the battery ECU is in the back with the HV battery.

 

It probably isn't so important to wonder what might have cause your situation rather than to just start physically checking things to see if you can find where the problem actually is.

 

It doesn't seem like your car is broken in terms of functionality... But there's a connection issue during testing that is failing: "Lost Communication with Hybrid Vehicle Control System." Perhaps a different inspection service and disconnecting & reconnecting 12v when you arrive could help? Either that or borrow a Prius owning friend's ECU to pass inspection?

 

Sounds like you have already tried two different “tools” to pull codes. I do have a question. You are saying the car throws a code every time they hook up to it. Before you get to the shop you have no light on the dash? After they hook up to the car the lights are on ( check engine and or check hybrid system)
Yes once you disconnect the 12 volt battery the monitors will have to be reset before you pass smog.

 

Is 7E0 for sure the address of the ECM? I don't have them memorized, so I don't know; just asking.

I'm unsure because the OBDLink report seems to be reporting two rows of DTC information. Both are U0293, one is confirmed and one is historical, but one identifies the reporting ECU as "Engine and Electronic Controlled Transmission" and the other as "7E0".

If those are the same ECU, I'm not sure why OBDLink would identify it by name in the Historical row, but only by raw address in the Confirmed row.

It reminds me of this post, where a different app (Car Scanner) used the name for one reporting ECU when it knew the standard mapping for that address (Entry & Start/Smart key in that case), but reported just the raw address for an unfamiliar ECU (7EA in that case, which in that Gen 3 turned out to be the Power Management Control ECU).

I also seem to recall that the low bits of an address may carry some other meaning, so for example 7E0 and 7E8 may be the same ECU depending on whether the message is a query or response, but I've gone all fuzzy on the details.

 

I am at a loss!?? Sorry, hopefully someone else can chime in.

 

When dash lights come on and the error codes are logged the majority of the hybrid error codes will throw the hybrid into a safe mode where you often get engine only and no hybrid system, yet your description sounds like the opposite? I'd think that'd point to engine problems?

As for the 12v, disconnecting it is the similar to rebooting your personal computer and that reset will mean the car has amnesia and has to find all the settings and existing problems again.

Maybe if you called around and found a smog inspection business with lots of experience with this particular problem? Or maybe the smog service you went to is the source of the problem?

 

I once built a little box with some switches and a DLC3 plug, so I could carry it in my glove box, and plug in at the diagnostic port and use the switches for procedures involving the Tc and Ts pins:



It worked great at first, but after it was several years old, that changed. I would then get a rash of communication errors logged right away upon plugging it in (before even twiddling any switches!). That experience was recounted in this thread.

When I built it, I used a cheap DLC3 plug, whose pins were not plated to resist oxidation. After so many year, those pins reached the point where the simple act of plugging it in to the diagnostic port would turn the various ECUs' messages into gibberish.

As followed up in that same thread, I rebuilt my twiddler thing using a better-quality DLC3 plug with gold plating on the pins, and that version has been rock solid. I can even plug that one in and out while the car is on, and nothing reports a communication glitch.

So I wonder if the smog-check place is maybe using an old deteriorated cable and plug.

It could also be possible you have one or more sockets in your car's DLC3 connector with weak spring force. I think that's also been reported here once or twice.

 

I keep thinking the problem here is the smog inspector equipment and the only problem you have is you have to go to a different place and then if that works take your paper work back to the old place and demand a refund for using faulty testing equipment on your car. They'll be quick to give you your money back if you show an interest in reporting their equipment to the state.

 

Yes. The report gives the “Calibration ID – $7E0” as 34710000, which is listed in Toyota service bulletin T-SB-0088-08 (attached here) as a “previous calibration ID” for ECMs on model year 2006–2007 Prius cars. Using 0x7E0/0x7E8 as the CAN identifiers for the ECM is also strongly recommended in ISO 15765-4:2005, Road vehicles—Diagnostics on Controller Area Networks (CAN)—Part 4: Requirements for emissions-related systems, incorporated at 40 CFR § 86.1806 05(h).

Exactly: the ISO standard only recommends that ECU #1 should be the ECM, but it does assign 0x7E0 as the 11-bit CAN identifier for requests from external test equipment to ECU #1, and 0x7E8 for responses from ECU#1 to external test equipment.

Perhaps the confirmed DTCs are being read using service $03 (as defined in SAE J1979 or ISO 15031-5:2006) but the historical DTCs are being read in some other way that allows greater confidence in the identification of the source ECU.