Symptoms:

  • Pressure switch codes
  • Switch codes
  • Pressure control out-of-range codes
  • Slips, flares & bind-ups
  • Failsafe mode
  • Erratic TCC apply
  • Harsh shifts
  • Shift codes

Cause:

OE pressure switch laminate disc breached, preventing proper switch operation.

Correction:

Salvage the transmission control unit and restore normal shift operation by installing a set of four seals and laminate discs from the Sonnax pressure switch rebuild master pack.

6L45, 6L50, 6L80, 6L90, 6T70 (Gen. 1), 6T75 (Gen. 1)

Pressure Switch Rebuild Master Pack
Part No. 124740-28K

View Instructions Find a Distributor

Listed GM 6-speed transmissions often set various trouble codes related to failures of fluid pressure switches that are internal to the transmission electro-hydraulic control module (TEHCM). These codes may be accompanied by TCC apply problems or shift irregularities such as slipping, flares, harsh application, and bind-ups. As time goes by, the laminated portions of the pressure switches can breach, preventing normal switch operation. If more than one switch breaks down, failsafe mode can be triggered. Since switches cannot be obtained through OE channels, replacement of the TEHCM was the only previous remedy available.

It is no longer necessary to replace the expensive TEHCM assembly to rectify this concern. Installing Sonnax pressure switch rebuild master pack 124740-28K restores normal switch operation, eliminating codes and providing renewed shift performance in all ranges.

  • Allows salvage of expensive TEHCM
  • Installation tools included in kit

Before installing kit, test switches to verify proper electrical operation. Kit repairs laminate disc and seal failures only; it will not rectify electrical breakdown. See instructions for details.

  • Laminate Discs (40)
  • Seals (40)
  • Seal Installer
  • Piston
  • Seal Plunger
  • Laminate Installation Tool

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.

GM Gen. 1 6T70, 6T75 Valve Body Layout

GM Gen. 1 6T70, 6T75 Valve Body Layout

GM 6L45, 6L50, 6L80, 6L90 Valve Body Layout

GM 6L45, 6L50, 6L80, 6L90 Valve Body Layout

  • 6L45, 6L50, 6L80, 6L90, 6T70 (Gen. 1), 6T75 (Gen. 1) Pressure Switch Rebuild Master Pack 124740-28K
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All I need to say is WOW! Since getting the new tools and kit, I have done 4 transmissions and all went great. I want to say thank you to Sonnax for creating a kit that makes working on these transmissions a little easier.

Rino
Continental Transmission
Bridgeview, IL