AutoCodes – GMC – B1372 GMC

B1372 GMC Code - Device Ignition On and Start Circuit Low

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: B1372 GMC indicates Device Ignition On and Start Circuit Low.
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 2,271

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 B1372 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 B1372 GMC - Device Ignition On and Start Circuit Low - AutoCodes.com — B1372 GMC Code - Device Ignition On and Start Circuit Low

What does this mean?

What are the Possible Causes of the DTC B1372 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 B1372 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 B1372 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 B1372 GMC Code

1. What are the common symptoms of OBDII code B1372 GMC?

The common symptoms of OBDII code B1372 GMC include issues with starting the vehicle, the engine not turning over, and potential illumination of the Check Engine light.

2. What can cause the Device Ignition On and Start Circuit Low code B1372 GMC?

The B1372 code in GMC vehicles is typically triggered by a malfunction in the ignition switch, faulty wiring connections, a defective starter relay, or a problem with the starter motor itself.

3. How serious is the B1372 GMC trouble code?

While the B1372 code may not always prevent the vehicle from running, it can lead to starting issues and potential breakdowns if left unresolved. It is recommended to address the underlying cause promptly to avoid further complications.

4. Can I still drive my vehicle with the B1372 code present?

It is not advisable to drive your vehicle with the B1372 code active, as it can lead to starting problems and potential stalling, posing a safety risk. It is recommended to address the issue before operating the vehicle.

5. How do I diagnose and repair the B1372 GMC trouble code?

Diagnosing the B1372 code involves inspecting the ignition system components, checking for loose connections, testing the starter relay, and verifying the functionality of the starter motor. Repair may involve replacing faulty components, repairing wiring issues, or resetting the code after fixing the underlying problem.

6. Can a DIY enthusiast fix the B1372 code issue?

While some DIY enthusiasts may have the skills to diagnose and repair the B1372 code, it is recommended to seek professional help, especially if dealing with complex electrical systems. Incorrect repairs can lead to further damage or safety hazards.

7. How much does it cost to fix the B1372 GMC trouble code?

The cost of fixing the B1372 code can vary depending on the underlying cause, parts needed for replacement, and labor costs. It is advisable to consult a mechanic for a proper diagnosis and cost estimate.

8. Will disconnecting the battery reset the B1372 trouble code?

Disconnecting the battery may temporarily clear the trouble code, but it will not fix the underlying issue causing the B1372 code. It is recommended to diagnose and repair the problem to prevent the code from reoccurring.

9. Can extreme weather conditions trigger the B1372 GMC trouble code?

Extreme weather conditions, such as excessive heat or moisture, can potentially affect the electrical components associated with the ignition system and trigger the B1372 trouble code. It is essential to keep the vehicle well-maintained to prevent such issues.

10. Is the B1372 code specific to GMC vehicles only?

The B1372 trouble code is specific to GMC vehicles and relates to issues with the Device Ignition On and Start Circuit Low. Other vehicle manufacturers may have different codes or descriptions for similar problems in their systems.