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Prius Transaxel

We have recently gotten warning lights on our 2002 Prius and the codes suggest a problem with the transaxel. We have 120K miles and never have replaced the fluid. The Toyota mechanics say a $5000 replacement of the transaxel is the solution. Has anyone else out there experienced this problem, had the transaxel replaced, or found a cheaper solution to the problem? Has anyone had the problem solved (replacement) under warranty?

My wife wants to add the following: Actually, these warning lights have been coming on since April (3+ months) and they can be made to go off by turning the key on and off 4 times, sometimes 5 times. Once the lights go off, they do not usually come back on for some time. When they do return, it is always during a trip in which we have traveled at least 30 miles without stopping. So what does this mean? Do we really have a transmission problem and if so, why don’t the lights come on and stay on and why hasn’t the car broken down already? Could this be a glitch involving the warning light system or is that wishful thinking? Also, two years ago we paid $1,200 or so to replace the car’s computer because the warning lights were coming on at that time and sometimes the gasoline engine wouldn’t kick in. This time around, so far, there hasn’t been any indication that the gasoline engine isn’t kicking in properly so the car runs just fine – except for those pesky lights and the Toyota diagnosis of impending doom. So I guess my real question is this: does anyone know or care to speculate about what will happen if I continue to ignore the warning lights and Toyota’s advice about the need for a new transaxle?

Sounds like you neglected the car, now you are paying for it. When you are cycling the key on and off you may be somehow reseting the diagnostics and when you drive around for a while the computer picks up the fault again. You may very well need a new transmission. It also could be another bad computer, however I think the dealer is probably right in this case.

What lights? What codes?

The Prius Transaxle is a variable speed transaxle. The speed varies depending on the outputs of the engine and motor/generators. The trans fluidis merely a lubricant, and does not encounter high pressures like an automatic transaxle would. But, I’m guessing that if it hasn’t been changed, it probably hasn’t been checked either. There is also a separate cooling system for the transaxle and the inverter. If it is not checked/maintained, life will get bad. Using the wrong coolant will also ruin your day. The inverter is the hardest working non-moving part on the car, and generates/disapates heat regularly.
I have changed transaxles on priuses for reasons ranging from fried wirings to damage from wrecks. My suggestion is to find out exactly what the codes are, and ask what the reasoning is to warrant replacement. Then maybe after the repairs are done, keep a closer eye on the maintenance. It is a low maintenance vehicle, but weather and regions play a huge part as well as driving habits on what needs to be done when.

value 250

All I can add is that those warring lights are their for your good. Ignoring them can be costly or dangerous. Even if what is indicated by the light is not, remember that it is then hiding any additional warnings and the next one could be very expensive or indicate a safety problem.

It’s your car and your life, you make the choice.

P3120 is HV Transaxle Malfunction. The info code 250 is Motor temperature sensor performance problem. There is nothing on the flow chart of diagnostics in the Toyota repair manual for diagnosis. It simply states “Replac HV transaxle motor”. In my esperience, this is uually caused by being subject to extremely high temperatures, usually caused by low inverter coolant level (or incorrect coolant), or low transaxle fluid levels. So, whoever told you to replace the transaxle is correct. Sorry!

If it continues to operate (approximately normally) with the warning lights, you haven’t completely cooked it yet. I woul dbe quick about confirming that the inverter coolant loop i sproperly air-bled and pumping the fluid correctly. Possibly a new electric coolant pump is required.

Transaxle fluid replacement is certainly the only maintenance option we have for them gears. It is not guaranteed to make them last forever, but neither is it expensive to do. Now might be a good time.

Depending on odometer, that ECU replacement might have been a warranty repair. Wish folks would check in at PriusChat or the Yahoo groups before they pay the money. Sometimes, we can help.