Tool Required VB-FIX Required

Printpartsummary
Symptoms:
  • Code 742
  • Code P0741
  • Harsh TCC apply
  • Loss of fuel economy
  • Low TCC apply pressure
  • No lockup
  • Overheated fluid & TCC lining
  • TCC slip
Cause:

Bore wear at the TCC regulator valve reduces TCC apply and converter charge pressure. If valve sticks, TCC slip or harsh apply will result.

Correction:

Recover hydraulic control and renew TCC performance by reconditioning the bore and installing Sonnax oversized TCC regulator valve kit.

Tool Required VB-FIX Required

6T40 (Gen. 1), 6T40 (Gen. 2), 6T45 (Gen.1), 6T45 (Gen. 2), 6T50 (Gen. 1), 6T50 (Gen. 2)

Oversized TCC Regulator Valve Kit

Part No.

144740-16K

Oversized TCC Regulator Valve Kit
  • 144740-16k_combo

  • Oversized TCC Regulator Valve Kit

Small_144740-16k_combo Small_144740-16k

6T40 (Gen. 1), 6T40 (Gen. 2), 6T45 (Gen.1), 6T45 (Gen. 2), 6T50 (Gen. 1), 6T50 (Gen. 2)

Oversized TCC Regulator Valve Kit

Part No. 144740-16K

  • Regulator Valve
  • Shuttle Valve
  • End Plug
  • Spring
  • O-ring

Complaint:

  • Code 742
  • Code P0741
  • Harsh TCC apply
  • Loss of fuel economy
  • Low TCC apply pressure
  • No lockup
  • Overheated fluid & TCC lining
  • TCC slip

Cause:

Bore wear at the TCC regulator valve reduces TCC apply and converter charge pressure. If valve sticks, TCC slip or harsh apply will result.


Correction:

Recover hydraulic control and renew TCC performance by reconditioning the bore and installing Sonnax oversized TCC regulator valve kit.

Vehicles equipped with GM Gen. 1 and Gen. 2 6T40/45/50 transmissions can exhibit a number of TCC apply issues caused by bore wear at the TCC regulator valve. Slipping TCC, no TCC apply, fluid overheat and suffering fuel economy are common results of this wear. If the valve becomes stuck in the apply position, harsh TCC apply will be the consequence. If the valve is stuck in the release position, no TCC apply or TCC slip will occur. Installing Sonnax oversized TCC regulator valve kit 144740-16K re-establishes correct valve-to-bore clearances, restoring normal TCC operation.

  • Lengthened spools for additional bore contact and support
  • Hardcoat anodized aluminum valves combat premature wear
  • Annular grooves help center valves in bore to reduce future side-load wear

Required Tools

You need this if...

Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.

  • Test Locations

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Valve Body Layouts

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.

Valve Body Layout GM 6T40 (Gen. 1), 6T45 (Gen.1), 6T50 (Gen.1)

Related Tech Articles

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