03 still won't start. Only DTC 1259

Cool! The HV ECU is communicating and it is reading the accelerator pedal. But it has a bunch of signals: Prius Hybrid Vehicle ECU

Looking at the module voltages:

15.53 - 14.55 = 0.98 V. > 0.30 volt but less than 1.2
(should work but may throw a code once started)
​

Assuming the key-reader/immobilizer and HV ECU are 'in sync,' it sounds like one or more of the other signals may be fubar. If I remember correctly, TomFreed (sp?) may have had to resync the HV ECU and he described the procedure in one of his messages late last year. See if you can find it or I'll look for it later tonight.

Bob Wilson

 

Eliminate the obvious:

• read the shifter position from HV ECU - it should show "P" anything else and there is a shifter circuit problem. This could inhibit starting. Remember there is both a resistor and position switch network, if I remember correctly.
• verify the brake switch signal is correct when pressed - brake must be pressed to start car and it must be in "P". I don't remember if the AE can query the HV ECU to see if shows the "stop light" switch position.

What I doubt is if either of these conditions would trigger the code. They would ordinarily just inhibit starting.

Bob Wilson

 

That's correct.

 

I Google searched and found this link that describes the conditions setting the code:

http://www.autoshop101.com/forms/Hybrid16.pdf

Perhaps it is time to find IG2 to the brake ECU and measure the voltage?

Here is another PDF:
http://www.hybrids.ru/PriusNHW20/rm/rm1076e/m_05_0820.pdf

This one reads like my manual.

Bob Wilson

 

C1259 will not prevent the vehicle from starting.

 

Let's go over the basic symptoms:

1. If you switch the car to ignition - What are on the displays (photos?)
2. When you switch to 'start' - Does motor make any attempt to spin the engine?

BTW, I checked before starting home. The NHW11 does not require brake to start. As long as the display shows it is in "P", turning the key to start fires it off.

Bob Wilson

 

C1259 is a regenerative brake code, not a hydraulic brake code. There is no regen on a stationary vehicle.

 

There is no diagnostic flow chart for that code.

 

jk, will you please knock it off with the 100% unhelpful "wrong,
try again" pseudo-answers like you're trying to sound like you
know exactly what the problem is but are waiting to see if us
mere mortals can figure it out? Thanks.
.
_H*

 

You are reading many things into my post that simply aren't there.

I gave my opinion on what the OP should and shouldn't look for. It's right there in the thread. No one is hiding anything from you.

And the OP has been looking for a diagnostic flow chart for a specific code. However, no such chart or procedure exists. I mentioned that so that the OP can avoid wasting time searching for something that isn't there.

If that bothers you, simply skip over my post and move on to the next one.

 

Interesting. The battery ECU showed the module-pair voltages. I think it can also show the internal resistance.

My apologies! I'll fill this out for our 2003 in about 30 minutes. Then you can compare it to yours:

	Column 1	Column 2	Column 3
0	pair#	V	mOhm
1	1
2	2
3	3
4	4
5	5
6	6
7	7
8	8
9	9
10	10
11	11
12	12
13	13
14	14
15	15
16	16
17	17
18	18
19	19

I suspect, pure speculation, that the 1 V difference between min and max may be part of the problem.

Do you have a oscope or something to to look at the signals into and out of the HV ECU? The reason I ask is I could start recording, up to 44 mhz sampling rate, some of the HV ECUs. We could share the data and step-by-step, reverse engineer the interface ... if you have the patience and curiosity.

Thanks for your endurance. I know how maddening some of these problems can be. But I think you are close.

Bob Wilson

 

In my 2003 Prius Repair manual volume1 it says for DTC 1259 (DI-443)
"Malfunction in regenerative of HV ECU" check "HV Control system" and/or "HV ECU".

Perhaps if the system thinks there is a regen problem it won't let the ICE start since it would immediately go to charge as soon as it starts, and with any problem in this "charging system" it won't allow it to start. So in this case, and with the stated block voltages, now my guess is it's not the HV battery but maybe #1 look for more wires cut between the ECU's, and #2 maybe check all connections between transaxle (MG1) and invertor (three orange wires). Perhaps while you're at it maybe throw an ohmmeter on MG1's wires while disconnected and see if there's any shorts.
Although that would probably throw a diff dtc..
You didn't say how low the block voltages sag when trying to start or if you did please excuse my ignorance, I'm at work here. BTW Dirk
Best of luck on this - you're doing great! Tom

 

I agree but it occurs to me that you and I have:

• working NHW11s
• Auto Enginuity

Let's 'blue print' our working NHW11s by recording every variable we can from every ECU. We'll convert our data into tables and post the combined table in a new thread, a reference thread.

Dirk can use such tables to see where his NHW11 is different from ours. We can both use our tables as reference should we have an obscure fault show up in the future. Better still, we can see what our comparative vehicle numbers look like . . . looking for the range of 'normal.'

Ideally we need both a cold state, something Dirk needs, and a warmed up state. But such tables would go far in serving as a reference not only for us but future Prius owners. It will also help me in the scanner survey.

It may take a couple of hours but I'll try to collect the data and start the tables in a new thread. We like you Dirk but these tables will be reference and hopefully show the way to 'normal.'

LESSONS LEARNED:

1. The "Info" fields for HV ECU appear to be useless. However, they make column entries that can overflow the number of columns excel can hold - will enable all values and then turn off the 'Info' values. Will survey existing file, after trimming to make it excel compatible. Upon further inspection, the "Info n" entries will need to be surveyed individually.
2. "Record" only prompts once and overwrites the data file every time a different controller is selected - I've lost all of my 'cold' data. There may be a setting that allows merging the data into a file.
3. Communications settings - Vehicle Interface Type "ISO9141-2" and Initialization Type "KWP2000 Forced ECM Init" appears to avoid setting false codes in the ABS ECU. If I use type "OBD-II," I get false ABS codes.

Bob Wilson

 

since the vehicle was in a accident, did any of those connectors on the front of the transaxle get damaged?

 

there was a cut wire between the HV ECU and inverter, where is this wire located exactly, say if your standing in front of the vehicle is it to the right of the inverter?

and how did you repair this wire?