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  • Burnt converter
  • TCC apply & release concerns
  • TCC codes


Bore wear and/or broken sleeves create an unstable or mis-positioned valve. Mid-stroke will cut off cooler flow and overheat the converter. Bore wear at the signal end creates a cycling action of the valve, resulting in TCC slip or RPM cycle with the valve.


The Sonnax oversized lockup control valve and cutback valve kit restores TCC apply and release pressure control and corrects valve positioning. This kit works with modulated TCC apply systems only


Required tool kit F-94987-TL5 is no longer in production. Check with your distributor for availability.


Oversized Lockup Control Valve & Cutback Valve Kit
Part No. 94987-05K

This kit fits '98-later models: Isuzu NPR, GMC Forward Tiltmaster, Chevrolet Forward, Nissan UD and Mitsubishi Fuso Trucks.

You need this if... View Instructions

Vehicles with Aisin AW 450-43LE transmission may exhibit TCC apply and release problems, burnt converters and damage and loss of TCC friction lining. Wear is commonly found at different areas in the lockup control valve bore. Wear at the lockup control valve bore prevents the valve from stroking to the lockup position. Wear at the lockup plunger sleeve causes lower TCC apply and release pressures. Sonnax oversized lockup control valve and cutback valve kit 94987-05K restores hydraulic integrity to properly control the apply and release of the torque converter. The material for the valves has been upgraded from OE steel to hard-coat anodized aluminum. The precision sleeves are manufactured from highly wear resistant aluminum.

  • Valves are hardcoat anodized to reduce wear
  • Sleeves are manufactured from highly wear-resistant aluminum

This kit can only be used with modulated TCC apply systems.

  • Lockup Plunger Sleeve
  • Lockup Plunger Valve
  • Lockup Control Valve
  • Cutback Valve
  • Oversized Cutback Sleeve
  • Cutback Spring

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 450-43LE Valve Body Layout

Aisin aw 450 43le
  • 94987 05k combo
  • 94987 05k

You need this if...

A vacuum test at the port indicated fails to hold at least 16 in-Hg.

  • 94987 05k test