Problem car

[tomfreed]

Originally Posted by bwilson4web

OWCH!!! ... But this isn't too bad. It is the temperature probe sensor.

From pp. DI-263 for MG2:

• Transaxle, M4, pin 3 - MMTG R-W - H10, pin 9 HV ECU
• Transaxle, M4, pin 1 - MMT GR - H10, pin 2 HV ECU

From pp. DI-269 for MG1:

• Transaxle, M2, pin 4 - GMT B-R - H10, pin 1 HV ECU
• Transaxle, M2, pin 9 - GMTG G-W - H10, pin 8 HV ECU

As a quick hack, put a 1k ohm resistor on the HV ECU pins in question. This would spoof the thermistor resistance and that should let it run ... although not an optimal solution. Just keep your speeds under 70 mph in hot weather until you can get around to running a new pair of wires. Better still, run some ethernet cable that will provide 4-pairs. Use one pair for this function and you'll have 3-pairs available for future experiments. <grins>


Bob Wilson

I checked the wiring from mg2 2 pins connector to the ecm and it was good. The other multiple pins connectori have not. I have P3120 with ECM control module as shown on the Autoenginuity. Are you saying i should hack it to isolate the problem instead of getting another ECM?

[tomfreed]

Originally Posted by hobbit

Three "bad" transaxles would start hinting at me that the problem
is nowhere near the transaxle. Have you taken a megger to all
of your dead soldiers there, to check for winding problems?
Have you looked at the resolver signals coming back at the ECU
leads to make sure they're solid? When you replace one of these
guys [and your efforts wrangling those heavy suckers are quite
impressive, btw] it's very easy to damage the plastic connectors
carrying the resolver and temp sensor wiring -- they're sensitive
low-voltage things, they need to have NO flakiness back to the
ECU. I don't know if your Autoenginuity can give you those
info-codes correctly -- what version do you have, and have you
asked their support folks about how specific they're able to
get on the 01 - 03 Prius? This is one of the grey areas of
aftermarket scantools, those bloody-annoying info-codes.
.
But it sounds like it's time for a good point-diagnosis rather
than trying to parts-swap your way out of the problem...
.
_H*

You got confused! Those three's were not all come from the same car. I was a used car dealer and i had multiple Prius with different problem. I had bad tranny from LKQ where i bought so as doing the job 6 times in and out.

Bob Wilson gave me another pins to check and way to hack to isolate the problem so i am going to try that. Yesterday i got under the car and pulled the cable harness out and examined closely. Look good though! I am going try what Bob suggested if not i will order an ECM from LKQ. I spent thousand of dollars for parts for this car with them so i think they would allow me to return the ECM if the problem is still the same. That would tell me for sure it is not the ECM and somewhere else.

I am not too close to any qualified repair shop and i already took to the damn dealer twice already for diagnostic and so far the result they gave me did not fix the car. Those guys told me i did more tranny swap than they did. I am not impressed with dealer.

[bwilson4web]

Originally Posted by tomfreed

I checked the wiring from mg2 2 pins connector to the ecm and it was good. The other multiple pins connectori have not. I have P3120 with ECM control module as shown on the Autoenginuity. Are you saying i should hack it to isolate the problem instead of getting another ECM?

The 'hack' is cheap and quick and might give you an early indication. Certainly it is OK with power off to measure the resistance of the transaxle thermistor pins w/o the ECU plugged in. If you see 1-3k ohm, it should be OK. If it is open, then determine if it is at the transaxle or in the wiring. ... That is the approach I'd take.

The 1k ohm resistor looks like a 'cold' thermistor. If you jumpered it or put say a 100 ohm resistor in parallel, the ECU should see it as if the transaxle is 'burning up' and should throw a different code when you first start the car. This allows you to know the ECU was measuring the resistance.

Another approach, the Graham miniscanner has the ability to read out MG1 and MG2 temperatures. You might check your scanner to see if there is a similar function. If one read 'stone cold' and the other say 10-15C (ambient,) then you'll have a positive indication of where the problem lies.

Bob Wilson

[yardman 49]

Hello Tomfreed:

I guess I can give you credit for being "brave" enough to tackle the problems that you've been having. But there's an old saying, something to the effect that "you know just enough to be dangerous".

As you may be discovering, the Prius is not the kind of car that a "backyard" mechanic can fix easily. Not that it's impossible (some talented individuals have successfully replaced the PSD, for instance), but it would seem to me that it would be far better for you to read up on the inner workings of the car, and then try to perform diagnosis, rather than trying to learn as you go.

In my line of work I troubleshoot some very sophisticated laboratory equipment, and I've seen the results of users (and inexperienced service engineers) trying to "wing it" and fix things that they are not trained on. It's usually not pretty, and often they miss the real source of the problems (and create new ones) in the process. Possibly you've fallen into this same trap?

Although I've had to "learn as I go" in some situations (in cases where no one else knows the answers either), I've learned over the years to first go talk with our R&D engineers when trying to work on something that is complex and unfamiliar.

I know that this is all "water under the bridge" in your circumstance, but I just wanted to point out the obvious to you.

Maybe you'd be better off selling the Prii for parts and at least recoup some of your loss.

Anyway, that's my two cents.

[tomfreed]

Originally Posted by bwilson4web

The 'hack' is cheap and quick and might give you an early indication. Certainly it is OK with power off to measure the resistance of the transaxle thermistor pins w/o the ECU plugged in. If you see 1-3k ohm, it should be OK. If it is open, then determine if it is at the transaxle or in the wiring. ... That is the approach I'd take.

The 1k ohm resistor looks like a 'cold' thermistor. If you jumpered it or put say a 100 ohm resistor in parallel, the ECU should see it as if the transaxle is 'burning up' and should throw a different code when you first start the car. This allows you to know the ECU was measuring the resistance.

Another approach, the Graham miniscanner has the ability to read out MG1 and MG2 temperatures. You might check your scanner to see if there is a similar function. If one read 'stone cold' and the other say 10-15C (ambient,) then you'll have a positive indication of where the problem lies.

Bob Wilson

Can i have a connector pin layouts for mg1 and mg2 so i can measure the resistance? I recollect the A.enginuity i have can scan for mg temperature. I will look into this. Great info. Bob thanks a million even though it has not been fixed yet

[tomfreed]

Originally Posted by yardman 49

Hello Tomfreed:

I guess I can give you credit for being "brave" enough to tackle the problems that you've been having. But there's an old saying, something to the effect that "you know just enough to be dangerous".

As you may be discovering, the Prius is not the kind of car that a "backyard" mechanic can fix easily. Not that it's impossible (some talented individuals have successfully replaced the PSD, for instance), but it would seem to me that it would be far better for you to read up on the inner workings of the car, and then try to perform diagnosis, rather than trying to learn as you go.

In my line of work I troubleshoot some very sophisticated laboratory equipment, and I've seen the results of users (and inexperienced service engineers) trying to "wing it" and fix things that they are not trained on. It's usually not pretty, and often they miss the real source of the problems (and create new ones) in the process. Possibly you've fallen into this same trap?

Although I've had to "learn as I go" in some situations (in cases where no one else knows the answers either), I've learned over the years to first go talk with our R&D engineers when trying to work on something that is complex and unfamiliar.

I know that this is all "water under the bridge" in your circumstance, but I just wanted to point out the obvious to you.

Maybe you'd be better off selling the Prii for parts and at least recoup some of your loss.

Anyway, that's my two cents.

Oh believe me i already knew this but you see I already shot an arrow i have to follow it. I am close i can feel it. Well i know for certain if i have a factory repair manual and a good diagnostic tool it would make a big difference. Dealer they have this luxury since they have factory training and proper tool and document. I know for the fact that they are no smarter than the rest of us especially the brain power at this forum. Heck I took the car there twice already to have it scanned last year and not that the car still was not fixed i had a big fight with those bastards.

I fixed couple Prius successfully but these two 01 and 03 were stubborn and costly to fix and time consuming.

[bwilson4web]

Originally Posted by tomfreed

Can i have a connector pin layouts for mg1 and mg2 so i can measure the resistance? I recollect the A.enginuity i have can scan for mg temperature. I will look into this. Great info. Bob thanks a million even though it has not been fixed yet

I'll try to get all the connectors and all pins late this evening. I don't have my manuals handy right now. I had posted the connector names and the pins for the thermistors earlier.

Bob Wilson

[tomfreed]

Originally Posted by bwilson4web

I'll try to get all the connectors and all pins late this evening. I don't have my manuals handy right now. I had posted the connector names and the pins for the thermistors earlier.

Bob Wilson

Don't worry about the pin layout Bob I figured it out from the wiring color code. I got something today. First i start up the car and samething that is it ran for awhile then shut down with code P3120. It is confirmed that my scanner can read MG temp. and bunch of other functions see attachment. MG1 shows reading MG2 is flat nothing. I reset code and hooked up the 1k across MG2 sender end. Code wouldn't reset and i got the engine to run with same flat dead reading. I then hook up the 1k across ECM connector end and same thing dead!!!!! MG1 does show reading.

I went to the 03 Prius that has different code and pull the reading for MG1 and 2 temp. Both got reading.

I am concluding that the wiring and sensor are not the problem on the 01 and it is the ECM. I recollect this is the only thing i had not replaced on this car for the hybrid portion from last year repair. I did tried to replaced it with different year ECM and ended up with not fixing it. I wasted my money as they would not allow me to return it so i got pissed off and left the car unrepaired for a year now. I did sent the pictures of the ECM on previous posting but did not get anything back from you. Basically the car won't start with those other two ECM'S.

The question is this: is ECM interchangeable or does it have to be the same year for it to work?

Can you give me your expert opinion before i plunge some money to get the correct ECM? Thanks Bob. Thanks to your help now i am getting somewhere and hopefully i don't have to do a tranny again

[bwilson4web]

Originally Posted by tomfreed

Don't worry about the pin layout Bob I figured it out from the wiring color code. I got something today. First i start up the car and samething that is it ran for awhile then shut down with code P3120. It is confirmed that my scanner can read MG temp. and bunch of other functions see attachment. MG1 shows reading MG2 is flat nothing. I reset code and hooked up the 1k across MG2 sender end. Code wouldn't reset and i got the engine to run with same flat dead reading. I then hook up the 1k across ECM connector end and same thing dead!!!!! MG1 does show reading.

I went to the 03 Prius that has different code and pull the reading for MG1 and 2 temp. Both got reading.

Progress! You're doing the work, I'm just a bystander (with the book. <grins> )

Originally Posted by tomfreed

I am concluding that the wiring and sensor are not the problem on the 01 and it is the ECM. I recollect this is the only thing i had not replaced on this car for the hybrid portion from last year repair. I did tried to replaced it with different year ECM and ended up with not fixing it. I wasted my money as they would not allow me to return it so i got pissed off and left the car unrepaired for a year now. I did sent the pictures of the ECM on previous posting but did not get anything back from you. Basically the car won't start with those other two ECM'S.

The question is this: is ECM interchangeable or does it have to be the same year for it to work?

Patrick Wong is the expert in ECM versions but I strongly suspect a more recent ECM will work perfectly and give you the advantage of all software fixes that were done over the years. Patrick may have some recommendations on other, more affordable sources.

Originally Posted by tomfreed

Can you give me your expert opinion before i plunge some money to get the correct ECM? Thanks Bob. Thanks to your help now i am getting somewhere and hopefully i don't have to do a tranny again.

Not to worry, I think Orangeboy might be interested in one of your 'spare' trannies.

Bob Wilson

[Patrick Wong]

Tom is talking about the "ECM" which is aka the engine ECU. However, his pictures are of the hybrid vehicle ECU. If any ECU is at fault, it probably is the HV ECU, not the engine ECU. However its not obvious to me that the HV ECU is the issue here.

Here's the full list of HV ECUs that should work on 2001 models:
http://www.toyodiy.com/parts/p_U_200...EEBA_8433.html

89981-47062 was specified as the correct replacement part in TSB EG021-02 for 2001 and 2002 models that logged certain fault codes.

Since there are so many cars under discussion and so many transaxles in the photos, I'm a bit confused about what Tom has done on the 2001. I understand the DTC is P3120.

- Did that car suffer a front-end collision?
- Has the transaxle been replaced yet?
- If yes, how many times was it replaced?
- How do you know the replacement is good?

I think that Tom has done all that could be done given his access to diagnostic tools, and the time has come to seek help from a competent Toyota dealer, Art's Automotive or Luscious Garage.