September 30, 2005
Common complaints with '93-later GM 4T60-E units are falling out of lockup hot, codes 39, 740 and 1870, adverse lockup in cold weather, torque converter shudder and burn-up of the TCC lining. These complaints can be caused by a worn TCC regulator sleeve and/or a worn valve body bore in the isolator valve area. The TCC regulator sleeve design was changed in '93, and this newer design has an aluminum sleeve with a steel valve that continuously oscillates within the sleeve. This motion eventually wears the inner diameter of the sleeve and results in excessive leakage. This leakage allows the TCC apply oil to exhaust to the sump. Leakage also is caused by the hardened steel isolator valve wearing the aluminum valve body bore. This allows converter oil charge reduction and PWM boost oil loss. Install Sonnax TCC regulator and isolator valve kit 84754-01K to resolve these problems.