P1259 error code?

Despite his reaffirmation, I still think he's mixed up.

If it's a C1259, it's a code set in the brake ECU just to repeat that it has heard of some trouble code or codes from the HV ECU. (In turn, the HV ECU could have been speaking for itself, or for the Battery ECU.)

There are a couple of possibilities. One, the HV and Battery ECUs are two in the Prius that a lot of generic scan tools won't read, even though a lot of generic tools will read codes from the brake ECU (a lot of cars have brakes). So, it's possible that there are current trouble codes in the HV or Battery ECUs that he just doesn't know about because the scanner that was used didn't show them, but did show the 1259 from the brake ECU.

If so, you would want to know that, and make sure Techstream or a suitable-for-Gen-1 scan tool is used to get whatever info is there in the HV and Battery ECUs.

It is also possible that there were problems reported by the HV or Battery ECUs and they've been fixed, and the 1259 code just hasn't been cleared in the brake ECU yet. That was exactly the case with my Gen 1 when I bought it.

In that case, just a selective code-clear for the brake ECU should make that code go away, and it should not come back.

I would do the selective code clear for the one ECU rather than something broad-brush like unhooking the 12 volt battery, because if there is HV or battery trouble info, you don't want to make that go away.

Without Techstream, a selective brake-code clear can be done with a jumper wire and a certain number of brake pedal stomps.

-Chap

 

Hi Chap,

Sorry to digress, but selective code clearing is something I have been interested in doing in the past. Are you saying it is possible to do in Techstream?

I ask, because I wasn't able to see how that was done. When I press the erase button, there is no selection screen from which to choose codes to delete, it just goes ahead and deletes all DTCs. How do you go about a selective clear?

Cheers.

 

Well, it's my sincere belief that the jumper-plus-eight-pedal-strokes is a selective clear for brake codes.

I've also long believed that the clear button in Techstream, when on the screen specific to one ECU, gets directed to that ECU.

But it's possible that the only times I've done that have been when only that ECU had codes to begin with, so maybe I've never really seen whether it was selective or not.

-Chap

 

Thanks Chap, and I wasn’t doubting the info, more keen to master the technique.

I’ll give it a try at the next opportunity.

Thanks again.

 

My experience with the Techstream is if you have selected a specific ECU (HV, Brake, etc) the Clear selection only clear the codes specific to that ECU. Just went through a situation with a P3000 and P3009 due, I believe, to rain and high humidity, and after completely removing and cleaning all HV battery components (all contacts, terminals and buss bars) and reinstalling the battery, I cleared each DTC via individual ECU selection. All modules tested between 7.90 to 7.79. Matched modules and reassembled. All appears good. I knew going in the battery modules connectors needed cleaned so went right to it when codes appeared. Completely disassembled and cleaned the HV battery cooling fan and ducts also. Had moisture in truck due to left tail light being cracked. Replaced light assembly. We had a little rain last two days so system got flight tested. All appears fine. Happy Camper. Wife was having withdrawals as her Prius was down almost 2 days. Except for the weight of the battery, it was a very simple job.