P1777 Chevrolet Ignition Retard Request Circuit Fault

Possible causes

– Step Motor harness is open or shorted
– Step Motor poor electrical connection
– Faulty Step Motor

P1777 Chevrolet Description

The step motor changes the step with turning 4 coils ON/OFF according to the signal from Transmission Control Module (TCM). As a result, the flow of line pressure to primary pulley is changed and pulley ratio is controlled