02 prius transmissions slips

You don't actually have a conventional transmission. There is nothing to slip, it is 1 statically ratioed planetary gear system made up of 2 electric motor generators (MG1 and MG2) and 1 internal combustion engine (ICE).

Desribe what you mean by "slipping" and perhaps we can figure out what is really happening.

 

A gross oversimplification to call it a CVT, but nonetheless, the driving sensation under load is about the same. Generally, the transmission either works or it doesn't.

 

I did a search, this page from Luscious Garage could be helpful;
Luscious Garage | Blog | Gen 1 Prius Transmission Repair, P3009, P3120, P3125
First generation Prius are prone to transmission failure. 99 times out of 100 the issue is a bad MG2 stator. Winding insulation degrades, creating a short between turns and/or phases. Heat from the short (high current) burns through surrounding insulation, broadening the affected area.

Also should be added, regular changing tranny fluid helps postpone this problem, in my opinion.

 

Yes, you need to put in that $200 trans. Just to be clear, the trans contains two electric motors, and one of them in yours is clearly failing. Replacing the electric motor can be done, but not for $200.

 

Like we have been trying to tell you, the "trans" is not a "transmission" in the general sense but the entire shebang.

 

Do not spend $500 having a BAD used tranny put in your car. The MG2 stator windings burn up in these cars. It is just about the only thing that goes wrong with the trannys. The stator can be easily checked by removing the end cover on the junk yard tranny. Once the cover is off there are only three bolts holding the stator in place. Typically they burn on the top back side. Read the link for Lucious Garage.

Brad

 

That was the wrong transaxle to purchase. You need one that came from a Prius that was hit from behind and has no known problems with the transaxle. It would be a waste of $500 to install a known bad transaxle.

I really doubt that your mechanic, unless he has experience in rebuilding Prius transaxles, will be able to salvage either of the failed units.

The Prius transaxle is composed primarily of the two motor generators, plus the power split device which is like a differential.

+1

 

I thought $200 was too good to be true, for a trans that came out of a wrecked but working car. That $200 trans probably has the same problem electric motor as the one in your car right now.

 

A p3120 250 code is "Motor temperature sensor problem". Toyota does not elaborate if this is for MG1 or MG2. Does your car go backwards ok? The MG2 alone pushes the car in reverse. If your car goes backward there is hope for your tranny. Does it work better cold when just started? Can you hear the tranny/inverter coolant pump running? It is located behind the drivers headlight. These pumps are prone to failure. A Scangauge II can measure MG1 and MG2 temps.

Brad

 

All of this suggests you are really going to end up paying out the wazoo because it seems that nobody making the decisions knows anything about Prii.

If you know nothing, I highly doubt you can do an MG swap.

 

tym2brn,
The stator is the stationary part of an electric motor. A motor has 2 basic parts. A stator, attached to the housing (does not move) and a rotor (windings attached to a shaft that rotates). See picture below (not an actual Prius motor but a good basic representation). I don't know how hard it is to replace just the motor in the transaxle but, I'm pretty sure it can be done. I would say the level of expertise required to do it would be very high. I might try it but I would go into the job knowing I might not be able to accomplish it.



Here's what the transmission looks like (cutaway view of an actual Prius transaxle)

 

If you can't hear it, its not working.

 

btw... i seriously doubt a local mechanic is going to give you any sort of proper diagnosis when it comes to the electric motors... the gears are simple and really don't need servicing... it's all on the electric side. even toyota master techs tend to mess up on diagnosis with the electric motors. it requires a lot of knowledge (i know a lot about them but even I wouldn't try a swap). most shop mechanics don't know what to look for in their measurements. a few people on here might know off hand what the resistance in the windings should be. if they share that knowledge, you could tell your mechanic and he can do a test on the electric motors themselves to see if the windings truly are shorting out or not.

then.... since you'll know... you can go do the junk yard with an ohm meter and check for yourself before you purchase... (kinda the only way to do this imo)

 

Ideally your mechanic "MegsOut" the orange wires of MG2 with a Megger (MegOhm meter). If low resistance, the windings are toast.

It's very rare to have a mechanical problem with Gen1 tranny.

Prius 1st gen - Replacing Transaxle

And you don't need to remove the engine entireley from the car. Jack car up, remove lower subframe, lower engine and tranny enough to separate tranny from engine and suspend engine while you have tranny out. ....also, tell your mechanic there are no torque converter bolts to remove on a Prius. Tranny mates to the engine like a manual tranny does in a normal car...i.e. just an input shaft.