TSB's

Binding GM tranny

This TSB applies to 2009 Chevy Silverado, Express, Trailblazer, Colorado; 2009 GMC Canyon, Envoy, Savana and Sierra; 2009 Hummer H3 and 2009 Saab 9-7x vehicles, equipped with the 4L60 automatic transmission.

Some customers may comment on a condition of bind when the transmission shifts into fourth gear and or no second or fourth gears. During disassembly of the transmissions, technicians may find that the 2-4 band item 602 in SI document 1553208) and the overrun clutch (645) are both distressed while no other clutches are damaged.

This condition may be caused by the oil seal ring grooves on the turbine shaft (621) being improperly machined. Improperly machined seal grooves can allow the forward clutch to apply fluid leak into the overrun clutch apply circuit and apply the overrun clutch. This will cause a bind condition between the overrun clutch and the 2-4 band in fourth ger.

If only the 2-4 band and the overrun clutches are distressed and no other clutches are damaged, replace the input housing and turbine shaft assembly during the transmission repair. Failure to replace the input housing and turbine shaft assembly could result in repeat transmission damage.

Be sure to follow the repair process thoroughly and complete each step.

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