AutoCodes – Generic – P1778

P1778 Code - Step Motor Function

Quick Answer

The step motor's 4 aspects of ON/OFF change according to the signal from the Transmission Control Module (TCM). Common causes include Faulty Step Motor, Step Motor harness is open or shorted, Step Motor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P1778 indicates Step Motor Function.
Common causes: Common causes include Faulty Step Motor, Step Motor harness is open or shorted, Step Motor circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 86,129

How popular is this code, among other codes? Medium

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Sep 29, 2020

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
Comments
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Code P1778 Description

The step motor's 4 aspects of ON/OFF change according to the signal from the Transmission Control Module (TCM). As a result, the flow of line pressure to the primary pulley is changed and the pulley ratio is controlled. This diagnosis item detects when the electrical system is OK, but the mechanical system is NG. This diagnosis item detects when the state of the changing the speed mechanism in the unit does not operate normally. The Diagnostic Trouble Code (DTC) will set when there is a great difference between the number of steps for the stepping motor and for the actual gear ratio.

OBDII Code P1778 - Step Motor Function - AutoCodes.com — P1778 Code - Step Motor Function

What does this mean?

What are the Possible Causes of the DTC P1778?

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

How to Fix the DTC P1778?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1778 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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Information for Specific Makes

P1778 Acura — Clutch Pressure Control Solenoid Valve 'C' Circuit
P1778 Honda — Clutch Pressure Control Solenoid Valve 'C' Circuit
P1778 Hyundai — Electro Valve Output Malfunction
P1778 Infiniti — Step Motor Function
P1778 Nissan — Step Motor Function

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.