AW55-50SN Solenoid Kit 2001, new and ready to install. Fits the AW55-50SN. Ships fast from the USA.
If your Volvo S60, V70, XC90 or S80, Saab 9-3 or 9-5, Saturn Vue or Chevrolet Malibu with the Aisin five-speed engages late, slams the 2-3 shift, flares between gears or surges at cruise when the converter clutch should be locked, the linear solenoids that control pressure inside the valve body are a prime suspect. This is a new EPC linear solenoid kit (part number K59927D, also referenced as A89428K) for the Aisin Warner AW55-50SN and its relatives, the AW55-51SN, AF33-5 and RE5F22A, in 2001 and later applications. It ships from a US warehouse.
The AW55-50SN uses on/off shift solenoids to move its shift valves, but the quality of every engagement and shift comes from three linear (variable-force) solenoids that the TCM drives with a duty cycle. Sonnax identifies them as SLT, SLS and SLU. SLT sets the throttle-dependent pressure that drives line pressure and the C-1 clutch apply; Sonnax gives SLT pressure as starting near 5 psi in Drive and rising with throttle and load to about 80 psi. SLS is normally open and controls clutch feed pressure at the shift pressure control valve. SLU is normally closed and controls converter clutch apply, B-4 servo apply and B-2 neutral control. All three are fed by a solenoid modulator valve that caps their maximum pressure.
Because these solenoids set pressure rather than just opening and closing, a weak coil or worn solenoid valve does not usually cause a no-shift. It causes bad shift quality, and the TCM may fall back to a high-pressure failsafe that makes everything harsh.
Scan the TCM first and note any pressure control or solenoid codes. Check fluid level and condition carefully; Sonnax notes that low fluid or overfill on this unit causes erratic pressure and poor linear solenoid control by itself. Measure each solenoid's resistance at the connector: Sonnax lists the AW55-50SN solenoids at 5.0 to 5.6 ohms. Then gauge it. Compare C-1 pressure with B-4 pressure on the 2-3 shift; B-4 should follow C-1 and never sit more than 10 psi below it. If both pressures look correct and the shift is still poor, the problem may be worn valve body bores rather than the solenoids, especially the solenoid modulator bore. Our AW55-50SN service guide covers the bore wear pattern, and the Aisin harsh and delayed shift guide lays out the other causes worth ruling out.
The listing calls this kit a direct replacement for the three linear solenoids in 2001-and-later AW55-50SN, AW55-51SN, AF33-5 and RE5F22A transmissions. Be aware that the SLT and SLS solenoids changed during production. Sonnax documents early and late versions with different bracket slots, bracket widths and manifold lengths, and a late SLT with the connector pointing down that needs a matching Volvo harness. Lay your old solenoids next to the new ones and compare the connector orientation and bracket before you bolt anything in. If you are unsure, send your year, vehicle and VIN and we will check it. If the whole unit is coming apart, the AW55-50SN master rebuild kit covers the frictions, seals and gaskets for the job.
If the pan shows heavy clutch material or the shifts were slipping for a long time, solenoids alone will not save it. Look at the AW55-50SN overhaul kit, and if the bores are worn, a complete AW55-50SN valve body is often the faster fix. For a full refresh of the on/off shift solenoids too, see the 8-piece AW55-50SN solenoid set.
| Fits | AW55-50SN 2001 |
| Part type | Solenoid Kit |
| Condition | New |
| 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.
The listing covers the Aisin Warner AW55-50SN, AW55-51SN, AF33-5 and RE5F22A in 2001 and later applications, found in Volvo, Saab, Saturn, Chevrolet, Opel and Nissan models. Compare connector orientation and bracket style with your old solenoids, or send your VIN so we can check it.
No. This is an EPC linear solenoid kit aimed at the three pressure-control linear solenoids (SLT, SLS and SLU). The on/off shift solenoids are a separate purchase; our 8-piece AW55-50SN solenoid set covers shift, pressure control and TCC solenoids.
Delayed engagement, flared or harsh upshifts (often the 2-3), converter clutch slip or RPM fluctuation at cruise, and harsh failsafe shifting after a pressure code. Low or overfilled fluid causes the same erratic pressure, so check the level first.
Sonnax advises against swapping SLT and SLS solenoids between cores because they are calibrated to the valve body. Install a matched set on the valve body you are keeping.
It depends on the vehicle maker. Volvo and Saab use Aisin JWS 3309 or AW-1 family fluid by part number, while GM-branded Malibu and Vue units use Dexron VI. Match the vehicle's specified fluid, not the color of what drained out.
Clear the codes and allow the TCM to adapt over several drive cycles. Some Volvo applications also have TCM software updates that affect engagement and 2-3 shift feel, so check for a reflash if the shift is still poor.
