MR2-S SMT Repair/Maintenance

Toyota chose to install a unique transmission option in some 2001-05 MR2 Spyders. The SMT transmission is an automatically shifted manual transmission with a single clutch. It offered near-automatic convenience and clutchless operation for those not comfortable with a conventional manual transmission. While it does not have the power loss typical of conventional automatic transmissions it lags behind the performance of manual transmission models due to its slow shifting speed and lackluster launch performance. This was the only transmission option offered in Australia.

With age the SMT transmission has gotten a bit troublesome and has proven complicated and expensive to repair. Swapping to manual transmission has become a very popular solution, offering much improved performance and reliability. See this PAGE for information on that option. We offer the information below for those who wish to maintain or repair their SMT transmission.

First, even the best Toyota dealership service departments and independent service shops are generally completely unfamiliar with the SMT transmission. Toyota’s documentation is very poor, leading most dealer mechanics to just start guessing and swapping out transmission computers and hydraulic units at thousands of dollars per guess until they manage to get the car running again. Monkeywrench Racing has more experience with these transmissions than any shop in the world and we do offer repair service. If you wish to bring/send your car to us for repair or maintenance please email us at to arrange the job. Cost varies depending on the repair but it’s a sure bet that we’ll cost you less than taking the car elsewhere.

We stock a full line of new and used parts for the SMT application:

The SMT fluid should be flushed and filled every 5 years or 50,000 miles. It is a unique fluid so be sure to use Toyota OEM fluid. It does get dirty and absorbs moisture which accelerated failure of the HPU and GSA units.

Don’t use brake fluid!!! It causes several of the critical internal seals to swell and fail prematurely, causing leaks and malfunctions! See picture- on the left are seals removed from units that ran on proper SMT fluid. On the right are swollen (failed) seals removed from units run on brake fluid.

Clutch Replacement:
Not a very complicated job, most service shops can handle it. Uses the same flywheel and clutch as the manual transmission model. Lightweight flywheel is a great upgrade, does improve performance and increase shift quickness, and has no downsides. OEM replacement or stage 1 street (more torque capacity) clutches work fine. The critical thing is to perform the SMT relearn process after the new clutch is installed. You can get a Toyota TIS software/cable kit HERE and do the job with a laptop. Or bring it to us or your local dealer.


HPU pump runs longer than 30 seconds when you open the driver’s door (usually causes errors and malfunctions while driving):
HPU has excessive wear and is having trouble building the necessary line pressure. HPU must be replaced. They are no longer available new but MWR rebuilds them good as new.

GSA leaks:
This is generally from the clutch actuator rod rusting, destroying the seal. The rod and seal cannot be serviced so the GSA must be replaced. At this point there is generally other internal rust from neglecting the fluid changes so the unit is not in good shape overall.

Don’t forget the GSA ALIGNMENT TOOL

Functionality problems:
This is where it gets tricky. The SMT system does have its own error codes but these are notoriously vague and unhelpful, sometimes even misleading.

70%+ of the time if you’re having intermittent issues like gear light coming on, failure to select a gear while driving, or failing to complete the relearn process you have a damaged or worn out GSA. it should be replaced with one of our rebuilt unit, which will also eliminate any GSA leaks you’re dealing with (fairly common)

The travel and pressure sensors do fail at times but it’s more likely that you will get a useful trouble code for this, making diagnosis much easier. MWR carries a full line of used and new sensors, replacement hoses and other SMT parts needed for maintenance and repair. You won’t find these parts anywhere else!

Toyota SMT Tech Manual with Error Codes

Code tips:

P0942: HPU accumulator pressure
This indicates that the SMT system is running the pump and attempting to achieve a target fluid pressure in the HPU’s accumulator but it is failing to achieve that pressure reading. If the code is new and no changes have been made to the system then it could be a worn or failing pump. This is especially likely if the pump runs for a long time and is not especially loud. If the pump runs very frequently for shorter periods of time then it is more likely a failed accumulator. We are also seeing more and more frequent pressure sensor failures- this can often result in the pump running for longer periods of time and making a much louder higher pitch noise which is the internal overpressure valve opening – the pump is making more than enough pressure, but due to a bad sensor the TCU believes pressure is still too low. Pressure sensor needs replacement. This overpressure condition can sometimes also damage the accumulator or even the pump if run like this for extended time.