AutoCodes – Generic – P1826

P1826 Code - Internal Mode Switch Circuit 'C' High

Quick Answer

With the engine speed at least 500 rpm for 5 seconds, Fuel Shutoff inactive, engine torque more than 20 ft-Ibs, the Powertrain Control Module (PCM) detects that the Internal Mode Switch (IMS) 'C' signal was in a high state while the gear ratio indicated 1st, 2nd or 3rd gear, condition met for 0.5 seconds. Common causes include Faulty Internal Mode Switch, Internal Mode Switch harness is open or shorted, Internal Mode Switch 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: P1826 indicates Internal Mode Switch Circuit 'C' High.
Common causes: Common causes include Faulty Internal Mode Switch, Internal Mode Switch harness is open or shorted, Internal Mode Switch 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 21,913

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 21, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P1826 Description

OBDII Code P1826 - Internal Mode Switch Circuit 'C' High - AutoCodes.com — P1826 Code - Internal Mode Switch Circuit 'C' High

What does this mean?

What are the Possible Causes of the DTC P1826?

Faulty Internal Mode Switch
Internal Mode Switch harness is open or shorted
Internal Mode Switch circuit poor electrical connection

How to Fix the DTC P1826?

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 P1826 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.

Need more information about the P1826 code?

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Need Help with the Code?

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Information for Specific Makes

P1826 Buick — Internal Mode Switch Circuit 'C' High
P1826 Cadillac — Internal Mode Switch Circuit 'C' High
P1826 Chevrolet — Internal Mode Switch Circuit 'C' High
P1826 Ford — Transmission 4-Wheel Drive Low Clutch Relay Circuit To Battery
P1826 GMC — Internal Mode Switch Circuit 'C' High
P1826 Mitsubishi — Shift Fork Position Sensor 2 System Voltage High Range Out

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.