Shuddering transmission??

Shuddering is usually one phase open on the motor which is the P3120. Did you test that when MG2 out? Replace the trans.

Luscious Garage | Blog | Gen 1 Prius Transmission Repair, P3009, P3120, P3125

 

No it will not. See my first post up top again as I just linked it.

Its shuddering becasue the mg is extremely out of phase with one phase open.

 

Btw, LG garage gen1 shuddering post was the second hit on a google search. Was quicker than putting the lg garage name in and searching there blog.

 

I answered your coast in neutral question in post #4. It will not shudder in neutral because mg2 is not energized.

 

Did you see on LG you can replace mg2 with the trans in the car on a G1. When you get it out you will probably find the burnt winding with your nose.

 

Yes I read your entire post. It says you didn't find any "burnt spots" which means your looking and its probably buried in the bundle and not readily visible. Try smelling. I know its lost a phase and I know its got an open winding.

 

It is rare that there's no obvious burn mark though. Was the car in an accident and maybe one of the three 3 phase Hi V orange cables to the trans is damaged?

You already replaced the Invert and same codes so must be a hard to see burnt winding. Usually there catastrophic burns.

See if its stinky along the bundle. If so pry the winding bundle apart and see if any burn marks.

Pictures of mg2 windings area. Good clear focused close up pictures please.

 

Did you measure MG2 windings with a megger or at least a regular ohm meter?
(you should have done that before you opened the tranny to "look" for burnt windings).
A real bad MG2 can be detected with a $5 ohmmeter. Unhook all orange MG2 cables from the inverter (MG2 is the square area, not the round area on the inverter). Check resistance between each orange cable and ground. If you have any dead shorts MG2 is hosed. You can get better information with a true meager, but a cheapo meter works in many situations.

 

I would also suggest checking resistance across all three stator wiring phases, one phase at a time. If an open circuit is found, that would be evidence that particular wire phase has a burnt winding causing the open circuit.

 

Looking over this thread, I've seen some things posted that don't completely square with what I understood to be the typical failure mode for the MG2 stator. As I understood it (from good descriptions by sources like Luscious and Arts), the typical beginning of trouble is a failure of the winding insulation that leads to a short--not an open. What results is effectively a closed-loop conductive path right within the stator itself. Because the rotor's made with permanent magnets, this turns the MG into a generator with no OFF switch. Any time it turns, it will transfer energy into the shorted loop of stator winding, heating it up, further burning insulation so that once begun, the failure inevitably progresses. It doesn't matter whether the car is on or off, or even whether the motor cables are disconnected from the inverter, because the magnets are permanent and the conducting loop is totally self-contained within the MG. It will shudder (and further cook itself) any time the wheels turn.

Unhappily, it all seems pretty consistent with what you're observing. Best wishes for an affordable repair.

-Chap

 

The only thing I would add is normal temperatures are:

• ICE > MG1 > MG2 (the end unit)

When MG2 stator fails, a generator with short and no OFF:

• ICE > MG1 < MG2 (initially)
• ICE < MG1 << MG2 (short trip)

There is no cure except MG2 stator replacement or transaxle replacement. The fault is in the short in MG2 stators.

Bob Wilson