Action Taken When the DTC Sets

WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The TCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
DTC 1688 is stored in TCM history.
The TCM defaults to a calculated unmanaged torque, gross, input value using throttle and engine speed.
The TCM inhibits torque converter clutch (TCC) engagement.