Circuit/System Description

WARNING: This page is about a different car, the 2010 GMC Sierra and 2010 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The Replicated TOS Signal circuit consists of the engine control module (ECM), the transmission control module (TCM) and a communication line, replicated TOS signal, between the two modules. The transfer case control module (TCCM) controls the 4WD low function. When the operator selects 4WD low, the TCCM commands the encoder motor to change ranges to 4WD low. The TCCM sends a message to the TCM. The TCM sends a message to the ECM over the Replicated TOS Signal circuit notifying the ECM that the output speed will be changing. The ECM then compensates for transfer case gear reduction in the transmission output shaft speed (OSS) sensor signal. The ECM uses the transmission OSS sensor signal to adjust shift points, line pressure and torque converter clutch (TCC) scheduling.