AutoCodes – Infiniti – P1778 Infiniti

P1778 Infiniti 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 Infiniti 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 4,566

How popular is this code, among other codes? Low

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
Cost to Diagnose
FAQs
Comments
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Code P1778 Infiniti 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 Infiniti - Step Motor Function - AutoCodes.com — P1778 Infiniti Code - Step Motor Function

What does this mean?

What are the Possible Causes of the DTC P1778 Infiniti?

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

How to Fix the DTC P1778 Infiniti?

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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1778 Infiniti 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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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.

Frequently Asked Questions about P1778 Infiniti Code

1. What does the OBDII code P1778 mean on an Infiniti?

P1778 indicates a problem with the step motor function in the transmission, which controls the CVT's (Continuously Variable Transmission) gear ratio adjustments.

2. What are the common symptoms of the P1778 code on an Infiniti?

Symptoms include difficulty shifting, loss of power during acceleration, poor fuel efficiency, and the Check Engine Light illuminating.

3. What causes the P1778 code to appear on an Infiniti?

Common causes include a faulty step motor, damaged wiring or connectors in the step motor circuit, or issues with the transmission control module (TCM).

4. Can I drive my Infiniti with the P1778 code?

Driving with this code is not recommended as it can lead to further damage to the CVT transmission and may cause unsafe driving conditions.

5. How do you diagnose the P1778 code on an Infiniti?

A mechanic will scan for codes, inspect the step motor and its wiring for damage, test the motor's resistance, and check the TCM for proper function.

6. How is the P1778 code typically fixed on an Infiniti?

Repairs may include replacing the step motor, repairing or replacing damaged wiring or connectors, or reprogramming or replacing the TCM if necessary.

7. How much does it cost to repair the P1778 code on an Infiniti?

The repair cost can vary but typically ranges from $300 to $1,200, depending on whether the step motor or TCM needs replacement.

8. What happens if I ignore the P1778 code on my Infiniti?

Ignoring this code can lead to severe transmission damage, higher repair costs, and potential vehicle breakdowns.

9. Can a low transmission fluid level cause the P1778 code?

Yes, low or dirty transmission fluid can impair the step motor's function and trigger the P1778 code.

10. Is the P1778 code specific to Infiniti vehicles?

No, while it is common on Infiniti models with CVT transmissions, it can also appear on other Nissan vehicles with similar transmission systems.

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