Symptoms:

  • Code 894, 1870
  • Overheated converter
  • Low TCC apply pressure
  • 3-4 Clutch burned
  • 1-2 Harsh
  • Low line pressure

Cause:

Excess wear at TCC regulator/isolator valve bore allows TCC apply pressure to exhaust.

Correction:

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

4L60-E, 4L65-E, 4L70-E

TCC Regulator & Isolator Valve Kit
Part No. 77754-03K

Fits '97-earlier Non-EC3 units only


You need this if... View Instructions Find a Distributor

In GM 4L60-E, 4L65-E and 4L70-E unit, severe wear of the TCC regulator valve bore is caused by oscillation of the OE valve allows regulated converter apply pressure to exhaust. This is a primary cause for TCC-related slip code P1870 and overheated converters. Exhausting apply pressure also diminishes line pressure, which can result in burnt clutches. Excess wear at the isolator valve bore reduces TCC apply pressure.

Reconditioning the bore and installing Sonnax TCC regulator and isolator valve kit 77754-03K restores normal TCC operation by shoring up the hydraulic integrity of this circuit.

  • 10% Higher apply pressure
  • Isolator valve lengthened to operate in unworn portions of the bore
  • Sleeve manufactured from highly wear-resistant aluminum
  • Hardcoat anodized aluminum valves combat premature wear
  • Annular grooves help center valves in bore to reduce future side-load wear

  • 4L60-E, 4L65-E, 4L70-E TCC Regulator & Isolator Valve Kit 77754-03K
  • 4L60-E, 4L65-E, 4L70-E TCC Regulator & Isolator Valve Kit 77754-03K

You need this if...

See the Part Selection and Reaming Options Instruction sheet to determine which combined Sonnax parts and tool kits will repair your GM 4L60-E PWM and Non-PWM valve body