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  • Low line pressure
  • No 3rd
  • No 4th
  • No 5th
  • 2-3 Flare
  • 5th Gear only
  • Delayed Forward
  • No lockup


The OE steel valve results in excessive clearance during hot operation and frequently sticks when cold. Bore wear can reduce available solenoid modulator pressure, resulting in delayed forward, flare on 2-3, TCC slippage or soft shifts overall. Bore wear at the inboard end results in excess solenoid pressure, improper gear or harsh shifts.


The Sonnax oversized solenoid modulator valve made of wear resistant hardcoat anodized aluminum re-establishes proper pressures. Additional support is given to the valve by adding length to the outboard spool.

55-50SN, 55-51SN

Oversized Solenoid Modulator Valve Kit
Part No. 59947-34K

You need this if... View Instructions

Aisin AW 55-50SN transmissions may exhibit multiple shift problems due to excessive wear in the solenoid modulator circuit. Loss of 3rd, 4th or 5th gear and no TCC apply are common along with low line pressure and flare shifts. Bore wear at the inboard end results in high solenoid pressure, improper gear or harsh shifts. The Sonnax oversized solenoid modulator valve kit 59947-34K allows the bore to be refurbished, and the hydraulic integrity restored for proper modulated solenoid pressure.

  • Hard-coat anodized to increase wear resistance
  • Added length at the outboard spool for additional valve support
  • Salvages severely worn valve castings
  • F-59947-TL34 tool kit can be used for both 59947-34K and 59947-35K oversized valve kits
  • Valve
  • End Plug

Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.

Aisin AW 55-50SN Valve Body Layout

Aw55 50sn vbl thumb

December 22, 2014

The Art of the Silver Bullet

Tory Royce

Topics: Diagnostics And Theory Shop Practices Rebuilding Tips Vacuum Testing Transmission GM Aisin AW 4L60-E Transmission 55-50SN Transmission

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  • 59947 34k combo
  • 59947 34k

You need this if...

A Wet Air Test in thelocation indicated with the valve blocked inward results in leakage out the neighboring line port, or a vacuum test fails to hold a minimum of 18 in-hg

  • 59947 34k test