This is an odd one that is driving me a bit crazy trying to figure out . . . My 2003 will be happily driving along and suddenly the engine will die (accompanied by the red exclamation, CEL, etc). This has happened while the car was stopped for a light, in a drive-through, cruising slowly, and even on the highway at 70mph. Does not seem to be tied to speed or conditions, whether I am accelerating or not, etc. It HAS been like 100 outside, but I park in the shade and the problem seems too random and intermittent for that to be the explanation. When it does happen I just coast down the road and can still steer/etc. All the accessories keep working, but the gas pedal does not respond and the engine stays off. I have to pull over and come to a complete stop, shift into park, and then I can restart the engine (it starts back up just fine). Sometimes it will happen again almost immediately (3x in a drive-through line once), sometimes it runs for a mile or two, or it might be fine for another week. The only thing Techstream sees is a p3100 code in the hybrid control ECU, but apparently that could be a LOT of different things. Anybody have ideas on a next step to narrow it down? I can't exactly just start swapping things, spares don't really exist!
I drove a bit to get the issue to repeat while I had the Techstream laptop connected, and this time got the sub codes: 392 and 159. 392 HV ECU internal error. Motor CPU malfunction 159 Motor ECU Communication Circuit Malfunction
P3100 is one of those DTCs with a lot of different INF codes defined. You mention having Techstream, which is good; you should click the snowflake on the P3100 and look in the freeze frame for the INF code(s). For several of the INF codes, the repair manual has relatively simple troubleshooting steps (like, for example, checking the single-wire "GO" circuit between the HV ECU and the ECM, if that's the INF code you've got). Several other INF codes also have troubleshooting steps that are comparably simple. (Then there are a pile of INF codes at the end that all just mean "HV ECU internal error", so if you have one of those codes, that's simple too, in a different way.) Toyota Service Information and Where To Find It | PriusChat Edit: I see you did post INF codes while I was posting this. In the 2001 manual I'm looking at, 159 and 392 are both in the long list at the end that all mean "HV ECU internal error".
Is that the module attached to the battery or the one on the dashboard behind the glove compartment? Or could it be either/both? If I can definitively trace it to one or the other I can look into getting a replacement.
If I do get my hands on a replacement, can I program it for the car using Techstream? I'm assuming it isn't even worth trying to troubleshoot the current one?
So it looks like this is the unit in question. I see multiple replacements by the year and part number, ranging from around $40 on eBay (https://www.ebay.com/itm/151041560601) to $6-900 from Toyota. The service manual has a lengthy section about connecting an external battery system during programming, which I take to mean I need to hook the 12v battery to a maintainer and make sure it doesn't drop too low. I have some chunky 13.8v supplies from ham radio that should do nicely. What I am wondering is CAN I even program this using Techstream or do I need a valid Toyota TIS account to pull the required calibration information?
I think you should be able to. The section in the repair manual about replacing it doesn't have a lot of special instructions. You should probably also review the section on the chip key/immobilizer, because I seem to remember a special procedure for a transponder key ECU and HV ECU to introduce themselves to one another when either one is replaced. I didn't see those instructions yesterday in the "replace HV ECU" section, so probably they're in the other section. But probably they apply when either ECU is replaced. The HV ECU might want the VIN to be programmed. I've never tried doing that but I might have seen something in Techstream for it. Of course a new ECU probably comes out of the box wanting its VIN programmed and a used one may already think it knows its VIN. I don't know if that complicates the programming any, but I'm sure people have reported putting in used HV ECUs here.
