P1778 Buick Transmission Reverse I/P Circuit Malfunction
Possible causes
– Faulty Step Motor
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
P1778 Buick Description
The step motor’s 4 aspects of ON/OFF change 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. This diagnosis item detects when electrical system is OK, but mechanical system is NG. This diagnosis item detects when the state of the changing the speed mechanism in unit does not operate normally.
Buick Vehicle:Buick Regal – ?Buick Riviera – ?Buick LaCrosse – ?David Dunbar Buick – Buick Century – Buick LaCrosse – Buick LeSabre – Buick Lucerne – Buick Park Avenue – Buick Regal – Buick Verano – Buick Enclave – Buick Encore – Buick Rainier – Buick Rendezvous – Buick Terraza – Buick Riviera