AutoCodes – GMC – B1440 GMC

B1440 GMC Code - Power Mode Master Input Circuits Mismatch

Quick Answer

The vehicle Power Mode Master (PMM) is the Body Control Module (BCM). Common causes include Faulty Ignition Switch, Ignition Switch harness is open or shorted, Ignition 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: B1440 GMC indicates Power Mode Master Input Circuits Mismatch.
Common causes: Common causes include Faulty Ignition Switch, Ignition Switch harness is open or shorted, Ignition 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 4,627

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Mar 17, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B1440 GMC Description

The vehicle Power Mode Master (PMM) is the Body Control Module (BCM). The ignition switch is a low current switch with multiple discrete ignition switch signals to the PMM for determination of the power mode. The PMM receives the ignition switch signals, and additionally a reference voltage signal from the BCM, through the ignition switch, and back to the BCM. There are redundancies within the PMM system that can allow operation of certain subsystems when there are faults in the ignition switch circuits. Other information such as serial data input from other modules and DTCs is also used to determine what power mode signals and information is transmitted by the PMM. The BCM logic uses all this information to identify the operator's desired power mode and activate specific discrete signals, and serial data messages for the operation of different subsystems as necessary. Other modules which have switched voltage inputs may operate in a default mode if the PMM serial data message does not match what the individual module can detect from its own connections.
The PMM will activate relays and other direct outputs of the PMM as needed according to the calculated power mode. Some relays controlled by the BCM are switched ignition voltage outputs that are pass through circuits within the BCM directly from the ignition switch. If these circuits short to ground, the B+ circuit fuse to the ignition switch will open.

OBDII Code B1440 GMC - Power Mode Master Input Circuits Mismatch - AutoCodes.com — B1440 GMC Code - Power Mode Master Input Circuits Mismatch

What does this mean?

What are the Possible Causes of the DTC B1440 GMC?

Faulty Ignition Switch
Ignition Switch harness is open or shorted
Ignition Switch circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC B1440 GMC?

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 B1440 GMC 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 B1440 GMC Code

1. What are the common symptoms of OBDII code B1440 GMC?

The common symptoms of code B1440 GMC include issues with the power mode selection, difficulty starting the vehicle, and possible illumination of the Check Engine Light.

2. What does the OBDII code B1440 GMC indicate?

The code B1440 GMC indicates a Power Mode Master Input Circuits Mismatch, which means there is a discrepancy in the signals received by the power mode master control module.

3. What are the possible causes of code B1440 GMC?

Possible causes of code B1440 GMC include faulty wiring or connections, a defective power mode master control module, or issues with the power mode switch itself.

4. How can I diagnose OBDII code B1440 GMC?

Diagnosing code B1440 GMC typically involves using a diagnostic scanner to retrieve the code, checking for any related symptoms, and inspecting the power mode switch and control module for any visible damage or issues.

5. Can I continue driving with OBDII code B1440 GMC?

It is not recommended to continue driving with code B1440 GMC present, as it can lead to potential starting issues or other electrical problems with the vehicle.

6. How can I repair OBDII code B1440 GMC?

Repairing code B1440 GMC may involve checking and repairing any damaged wiring or connections, replacing the power mode switch or control module if necessary, and clearing the code with a diagnostic scanner.

7. Is it possible to clear OBDII code B1440 GMC without fixing the underlying issue?

Clearing the code without fixing the underlying issue may temporarily turn off the Check Engine Light, but the problem will likely reoccur until the root cause is addressed.

8. Can a DIY enthusiast fix OBDII code B1440 GMC?

Depending on the individual's skill level and access to tools, a DIY enthusiast may be able to diagnose and repair code B1440 GMC, especially if it involves simple tasks like checking connections or replacing components.

9. How much does it cost to repair OBDII code B1440 GMC at a mechanic?

The cost of repairing code B1440 GMC at a mechanic can vary depending on the specific cause of the issue, but it may involve diagnostic fees, parts replacement costs, and labor charges.

10. How long does it take to repair OBDII code B1440 GMC?

The time required to repair code B1440 GMC can vary based on the complexity of the issue and the availability of parts, but it may take a few hours to a full day for a mechanic to diagnose and fix the problem.