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Sunday, September 19, 2010

Gen 1 Prius Transmission Repair, P3009, P3120, P3125

(This blog supersedes “Gen 1 Prius Transmission Failure” dated 10/28/2008.)

imageFirst 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.  Common symptoms can include:

1. Shudder during takeoff
2.    Louder whine during regenerative braking
3. Temperature warning light (red thermometer)
4. Master Warning Light (red triangle)
5. Diagnostic Trouble Codes (DTCs):

P3009: HV Leak to Ground
P3125, info code 287: Inverter Internal Short
P3120, info code 250: HV Transaxle Assembly Malfunction, Motor Temperature Sensor Performance Problem

Stator degradation can be confirmed in the service bay; LG maintains the necessary diagnostic tools and leads the industry in expertise.  All information is shared with the vehicle owner and documented in the work order.

Until now it was deemed cost prohibitive to service the motor rather than replace the entire unit.  In the last six months, however, two significant discoveries have been made:
1. It is possible to remove and replace the MG2 stator from behind the assembly endplate, with negligible disturbance to the motor resolver.

2. A replacement stator can be harvested from an MG2 assembly, available brand new from Toyota for a third of the price of the entire transaxle.

The result is a reliable service procedure that saves significant time and money.  Repair strategies of the past—replace the entire transaxle with brand new, replace the entire MG2 assembly with brand new, or replace the entire transaxle with used—are effectively obsolete.

The cost breakdown for stator replacement is as follows:

Labor, R&R MG2 Stator: $1080
MG2 Motor Assembly, Hybrid (Toyota P/N G1100-47040): $1288.74
ATF, Drain Plug Gaskets, Coolant: $47.39
Sales Tax: $126.01

Total: $2533.45

Other foreseeable costs:
Initial diagnosis: $60
Additional diagnosis with milliohmeter, megohmmeter, or impedance tester (if required): $100
HV Battery Test (to anticipate other high dollar repairs): $50

For questions or to book an appointment, use the contact page.

While not inexpensive, this repair significantly reduces the monetary and material cost of Gen 1 Prius ownership, postponing the day when a fuel-efficient car has to be replaced.

Credit for this service procedure goes to Jack Rosebro of Perfect Sky Hybrid Training.  For classes call 310-383-4800.

We publish our services online to promote ourselves and to inform hybrid owners of their service choices.  This is a complex procedure, and should not be undertaken without proper instruction.


View of the transmission endplate tilted into the wheel well:


MG2 rotor and stator removed together:


Typical view of burned windings:


Transaxle housing with stator and rotor removed:


MG2 assembly out of the box from Toyota:


View of MG2 stator with endplate removed, to be harvested:


New stator installed with original rotor:


Carolyn's avatarPosted by Carolyn Permalink Categories: Repair »

Thursday, September 02, 2010

Rebuilt HV Battery Packs - Toyota Prius Hybrid et al.

(This blog focuses on our rebuild services; read the original blog on Gen 1 battery failure here.)

Rebuilt HV batteries for the Gen 1 Toyota Prius are a convenient and cost-effective alternative to brand new. 

New ones cost $2299 list (which is a pretty reasonable IMO), but when you add up tax (9.5% in our dear city) and four hours in labor ($480 at LG; other shops/dealers will surely vary), you’re looking at three grand out the door.  You know what you’re getting (the same thing you had) so life expectancy should be nearly the same.  In our experience with *genuine* failures—cars that actually needed a pack, not just a wire harness (read the blog about P3030) or a cleaning (read the blog about P3009)—the probability bell curve peaks at 150,000 miles, tapering off in both directions. 

Besides offering new assemblies (purchased directly from Toyota) Luscious Garage also rebuilds battery packs in house.  I can’t honestly remember what prompted us to figure it out, two years and dozens of packs ago. It was probably a combination of plug-in conversion work (which inherently goes “out of the box” regarding HV batteries) and the drive to find a better way.  (There is also a shop in North Carolina—Taylor Automotive, d.b.a. ReInvolt Technologies—also selling rebuilds, for which LG is the Bay Area installer.  I’m not sure who was first, but, having spoken with Dave Taylor in person, our process sounds very similar.)

The benefits of rebuilds:

1. Rebuilt packs offer a significant cost savings.  We sell ours for $1500 (38 modules at $36/each and a new sensing harness for $120); with tax and six hours labor (two additional hours to cover the building process, which is therefore untaxed) the repair comes to $2361.  That’s over $600 less, which is real money.

image2. The modules come from young Gen 2 Prius (sourced from early totals or plug-in conversions) which have an upgraded design over the original Gen 1 module (pic: metal sided is Gen 2, all plastic is Gen 1) with better heat dissipation and lower internal resistance.  The difference is evident in the cars we service: all Gen 1s will have an HV battery failure; Gen 2s rarely do (despite many with very high mileage).

Thus, though the price is lower and the batteries are second-hand, we expect the rebuilt packs to last as long if not longer than the originals.  For most Gen 1 owners, this confidence combined with the cost savings will drive the decision. 

All packs are load tested to confirm battery health, and the results are included in the work order (learn more about battery testing here).  If I may say so, we build mighty strong packs, with identical performance to brand new units.

All of our rebuilds are guaranteed for one year (the same as new from Toyota) but we have yet to have any come back (and we don’t expect them to).


Labor: $720
38 NiMH, Gen 2 Prius Modules @ $36.30: $1379.40
Sensing Wire Harness, 82165-47030: $119.43

9.5% Sales Tax: $142.39

Total: $2361.22

Click here to book an appointment

View of our HV battery service area:


Stacks of bad Gen 1 modules:


Gen 2 module stacks:


With low mileage and plenty of future:


Carolyn's avatarPosted by Carolyn Permalink Categories: Repair »


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