AW55-50SN Valve Body 2005-2009, remanufactured and ready to install. Fits the AW55-50SN. Ships fast from the USA.
A harsh bang on the 2-3 upshift, a flare between gears, a delayed engagement after sitting at a light, or a converter that cycles rpm at light cruise are the complaints that send most owners of a 2005-2009 AW55-50SN looking for a valve body. This remanufactured unit is built for that late run of the Aisin Warner five-speed transaxle, the years when Volvo, Saab, GM and Nissan applications had all gone through several running changes to the solenoids and their brackets. It goes in as a complete hydraulic assembly, so you are not trying to rebuild bores in the driveway.
In this transaxle the computer does not apply clutches directly. It pulses three linear solenoids, SLT, SLS and SLU, and the valve body turns those signals into apply pressure for each clutch, the B-4 servo and the converter clutch. A solenoid modulator valve feeds all three and caps their maximum output. According to Sonnax, SLU handles converter apply, B-4 servo apply and B-2 neutral control, and it is also pulsed during the 1-2, 2-1, 2-3 and 3-2 shifts and on engagement into Drive or Reverse. That is why one worn modulator bore can spoil several shifts at once. Sonnax also notes that the three linear solenoids are calibrated to the valve body they came on, which is a big reason a complete, matched assembly makes sense on a high-mileage car.
Put gauges on C-1 and on the B-4 tap at the top of the case, in line with the linkage bolts. Sonnax says B-4 pressure should follow C-1 and never drop more than 10 psi below it. If C-1 reads about 160 psi the moment Drive is selected, the computer is probably in failsafe, and the 2-3 will be harsh no matter what valve body is fitted, so read codes first. A bad speed sensor or aerated fluid can force the same high-pressure behavior. If both pressure curves run parallel, initial C-1 is near 50 psi and the 2-3 is still harsh, the fix may be a computer update rather than hardware; do a key cycle and several drive cycles before deciding. With the valve body still installed you can wet air test the SLT port at 80-100 psi and watch for leaks at the side cover, SLT accumulator and the B-1 and C-1 control valves. Our AW55-50SN service guide covers the fill plug and band anchor mix-up that causes a no-3rd complaint after a fluid service, which is worth ruling out too.
This valve body is listed for the AW55-50SN from 2005 through 2009. The late years matter because Sonnax documents early and late SLT and SLS linear solenoids with different bracket widths and manifold lengths, and a late SLT with its connector facing down needs the matching harness used on the Volvo update. GM and Saab also run a different computer strategy than Volvo, and some shift solenoid positions differ between normally open and normally closed parts. Match the solenoid layout, bracket style and connector orientation on your old unit to this one, or send us your year, make, model and VIN and we will check it. If your car is a 2005 or 2006, compare it with the 2005-2006 AW55-50SN valve body, and see the rest of our Aisin range on the Aisin transmission parts page.
Drain the fluid, drop the pan and clean the pan and magnet before the new valve body goes in. Keep the linear solenoid connectors labeled and route the harness away from the speed sensors; Sonnax warns that the Hall-effect input and output sensors pick up stray signal from the solenoid wiring and can cause harsh shifts, high line pressure and phantom codes. Refill with a JWS 3309 type fluid and set the level by the factory temperature procedure. If the on/off shift solenoids are original to a high-mileage car, the AW55-50SN 8-piece solenoid set is a sensible add while the pan is off, and the AW55-50SN shift kit suits a rebuild where the clutches are also being serviced. Finish with the adaptive reset described in our relearn guide and give the computer several gentle drive cycles.
| Fits | AW55-50SN 2005-2009 |
| Part type | Valve Body |
| Condition | Remanufactured |
| Brand | OEM |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
It is listed for 2005-2009 AW55-50SN applications. Late units can differ in linear solenoid bracket width and connector orientation, so compare your old valve body to this one or send us your year, make, model and VIN before installing.
The 2-3 is controlled through the B-4 servo circuit. If the computer is in failsafe, a speed sensor is faulty or the fluid is aerated, B-4 pressure goes straight to maximum and the 2-3 slams. Read codes and compare B-4 to C-1 pressure before replacing parts.
Sonnax advises against swapping SLT and SLS linear solenoids between valve bodies without adjusting them, because they are calibrated to the valve body they came on. Installing the assembly as supplied is the safer choice.
Use a fluid meeting the Aisin Warner JWS 3309 specification and check the level at the temperature the factory procedure calls for. Generic multi-vehicle ATF is not a good substitute in this transaxle.
Yes. Reset the adaptive values with a capable scan tool, then drive several gentle cycles so the computer learns pressures for the new hardware. Some Volvo and Saab cars also benefit from a software update for 2-3 and 3-2 shift quality.
