Excess wear at TCC regulator/isolator valve bore allows TCC apply pressure to exhaust.
Recover hydraulic control and renew TCC performance by reconditioning the bore and installing Sonnax TCC regulator and isolator valve kit.
Severe wear of the TCC regulator valve bore 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 77754-04K restores normal TCC operation by restablishing the hydraulic integrity of this circuit.
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Contact a Sonnax Parts Distributor.
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