A stepper motor is known as a brushless DC device that divides a complete rotation into an equal number of steps.
These motors change pitch with the activation and deactivation of 4 coils, taking into account the signal provided by the Transmission Control Module (TCM). This results in the flow of line pressure to the primary pulley changing and consequently, the pulley ratio is controlled.
Diagnostic code P1777 OBD2 is set when a fault is detected in the stepper motor electrical system.
The P1777 OBDII fault code is stored for one of the following reasons:
The stepper motor may have faulty wiring.
The Step Motor circuit may be shorted or open.
The stepper motor may be faulty.
Possible solutions of the DTC code P1777
Steps to troubleshoot the P1777 OBD2 DTC:
Consult the TSBs.
Check all the wiring and connections of the stepper motor circuit for burns, corrosion, or wear and tear. If you find any of these conditions, make repairs if necessary.
Use the appropriate tools to take readings of the stepper motor circuit voltages, verify that the stepper motor circuit is not open or shorted. The results obtained in these tests should match the values specified by the manufacturer in the data source. If you detect a value different from the specified value, make the appropriate corrections.
Check the integrity of the Step Motor, taking into consideration the manufacturer's diagnostic recommendations. If you determine that it is damaged, replace it.