2003 With P3120 Transaxle Code

[orange4boy]

That is the standard error screen. Mine was exactly the same but my battery was fine and my steering was fine. Has anyone actually seen other two icons in red? I haven't.

Is the car idling smoothly? I have heard of one of the plug coils going bad and causing misfiring. Might cause a jerky motion and low power. Check for water in the spark plug holes. Water can collect there and drip down. That could also cause low power and a jerky engine.

Whether that can cause a transaxle failure code is anyone's guess. Some times the computer gets mixed up because of a low 12V battery.

The last independent mechanic to drive the car wrote "transmission wonky" How's that for a symptom description? It finally quit in the hands of the Toyota dealership who didn't bother to check the trans fluid level before taking it on a test drive.

[bwilson4web]

Originally Posted by kenopa

. . .
For Bob, we live in southern Indiana about 30 minutes west of Louisville, KY. I eat grits and wife drinks Dr. Pepper. Would you hesitate to buy 2010 at current time?

Hummm, usually I try to visit the Georgetown KY plant but making a left turn at Louisville works for me. However, I am trying to visit Re-InVolt in NC next weekend. I'm me think about the logistics.

Somehow it sounds as if one leg is lost. If you take off the windshield wipers and rain shield, you can access the MG2 terminal block:


If you open it up, disconnect the inverter leads and then measure the resistance between the three legs of MG2. Internally, all three stator windings are tied together in a "Y" configuration. What we need is the resistance between all three legs looking for either an "open" or a "short".

That the car seems to move OK on ICE power suggests MG1 is probably OK. MG2 is the likely source of jerkiness when moving the car about on EV mode. But I would not rule out the inverter (a much more affordable part!)

With the inverter leads free, measure the inverter lead-to-lead resistance and for good measure, reverse the measurement leads. If you have a manual resistance scale, use both the lowest and highest scale. Although it may seem silly, please minimize the potential for electrostatic discharge into the inverter leads (ESD wrist strap.)

I would also recommend unplugging, cleaning, and replugging in the MG1 and MG2 sensor interfaces. The reason is if any salt water ever gets there, a corroded connector could look exactly like a broken transaxle. There is another set in the car under the carpet of the sloping foot area where the hybrid vehicle ECU resides. Inspecting and reseating them is also probably a good idea.

These are the most extensive, not removing the transaxle, tests that can be done. Finding and fixing a dirty connector is a whole lot easier than replacing a transaxle. It sounds like the mechanicals are OK.

As for buying a 2010 Prius, it is a buyer's market. I would have no problem with buying either a new or used (non-crash) 2010 Prius. Given a choice, I would buy a used 2010 Prius with accident avoidance, automatic cruise control and lane assist in a hearbeat if you can get it closer to say $25k. New they were running over $32k.

We are keeping our 2003 Prius because it is paid-off and is a dandy commuting car. The 2010 handles errands, highway trips and bad weather driving.

Bob Wilson

[kenopa]

Not much new to report at this time. Cannot perform tests on MG2 windings due to lousy weather. Toyota service wants to see vehicle as this particular dealership has never seen a mechanically failed transaxle (so they say). Service mgr thinks the symptoms point to a "relay problem". If the trans has failed, they think vehicle is worth about $1500 in trade. I'm thinking that's a little low. We will go in to talk to service mgr on Wednesday and look at 2010's (they have plenty), then will probably have 2003 towed in to them next week for a full analysis. The more I think about symptoms (ICE starts and runs fine, "acceleration" real jerky/hesitant moving from stop, smooth acceleration as ICE takes over then vehicle died when it coasted), the more they might point to MG2 as not functioning. We'll see. Although vehicle has nearly 125K, we can't help but feel frustrated that she should have failed this soon.

[bwilson4web]

Originally Posted by kenopa

. . . We'll see. Although vehicle has nearly 125K, we can't help but feel frustrated that she should have failed this soon.

You have my sympathy ... it is not a good place to be. If you do let the dealership take a look at it, feel free to suggests the tests I've proposed. There are no guarantees in life but these are fairly 'cheap' tests.

I agree that $1,500 is low and faced with a similar, low-ball dealer offer, $2,700 for our 2001 Echo, I found a private buyer at work for $3,000. I think three parties were happy.

If you decide to DIY (be sure and evaluate your time and tool costs.) What scanner are you using to read the codes?

Bob Wilson

[jk450]

Originally Posted by kenopa

Not much new to report at this time. Cannot perform tests on MG2 windings due to lousy weather.

A conventional ohmmeter is not sensitive enough to detect a short in these windings. And an open winding would prevent the vehicle from moving. So unless you have an ohmmeter that can measure in thousandths of an ohm, you may want to skip the tests.

[kenopa]

Two things accomplished today. Took delivery of Barcelona Red 2010 Prius II and got back eval of the 2003. Was hoping for more info and an explanation, but this service department has never received a Prius with a failed transaxle (so they say) and they were not much help. They did provide two Techstream screen images, as follows:

Screen #1 apparently reports conditions when P3120 first appeared:
Water Temp Meter - 187 F
Engine RPM - 1440
Vehicle Speed - 32
Intake Air - 79 F

Screen #2 Showed Diagnostic Code C1259 - HV System Regenerative Malfunction

Don't see anything very exciting with 1st report, but second has me confused. I can't find reference to this code. Any thoughts out there as to what this might mean?

[jk450]

Screen 1 would have also listed the three-digit information code. You need that.

Ignore C1259 for now. It's a companion code to P3120. Focus on P3120.

[kenopa]

You're correct. Looked at Techstream Freeze Frame P3120 printout carefully and discovered Information 1 = 234.

As dealer does not want to repair vehicle (at any cost), am having it towed home this week, then will think about disposition (sell as-is, repair myself (doubtful) and then sell or have repaired and then sell. Strangely difficult to part with this little thing. It's just an old car. But somehow more than just that.

[Patrick Wong]

So you can't find any transmission shops in Indiana that are willing to install a salvage transaxle unit?

If you download the repair manual info from techinfo.toyota.com that would help to show the magnitude of the job.

[bwilson4web]

Or look at Tomfreed and Orange4Boy's photos. It does require heavy lifting and/or careful attention to jacks, jackstands, e.t.c. The reason for using a transmission shop is they have the tools to handle the heavy lifting ... but then they may not pay attention to torque values . . . Mixed bag.

Bob Wilson