AutoCodes – GMC – B0977 GMC

B0977 GMC Code - Start Indicator Control Circuit

Quick Answer

The Ignition Mode Switch has 3 LEDs that indicate the vehicle power mode. Common causes include Faulty Ignition Mode Switch, Ignition Mode Switch harness is open or shorted, Ignition 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: B0977 GMC indicates Start Indicator Control Circuit.
Common causes: Common causes include Faulty Ignition Mode Switch, Ignition Mode Switch harness is open or shorted, Ignition 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 867

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 Mar 11, 2021

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B0977 GMC Description

The Ignition Mode Switch has 3 LEDs that indicate the vehicle power mode. When the vehicle is in the Off mode, the Off LED may illuminate. Pressing the lower button of the ignition mode switch, the vehicle enters the accessory mode and ACC LED will illuminate. Keeping the lower button pressed for about 5-6 seconds, the vehicle enters run mode with the engine off and the START LED will illuminate. All these LEDs have the voltage supplied from the Body Control Module (BCM) through the ignition mode switch supply voltage circuit. The ground path for each LED is controlled by the BCM.

OBDII Code B0977 GMC - Start Indicator Control Circuit - AutoCodes.com — B0977 GMC Code - Start Indicator Control Circuit

What does this mean?

What are the Possible Causes of the DTC B0977 GMC?

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

How to Fix the DTC B0977 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 B0977 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 B0977 GMC Code

1. What are the common symptoms of OBDII code B0977 GMC (Start Indicator Control Circuit)?

The common symptoms of this code include the start indicator light not functioning properly, the vehicle not starting, or issues with the vehicle's ignition system.

2. What are the possible causes of OBDII code B0977 GMC?

Possible causes of this code may include a faulty start indicator control module, wiring issues in the start indicator circuit, or a malfunctioning ignition switch.

3. How can I diagnose OBDII code B0977 GMC?

Diagnosing this code involves using a scan tool to retrieve the specific trouble code, inspecting the start indicator circuit for any visible damage or loose connections, and testing the start indicator control module for proper functionality.

4. How can I repair OBDII code B0977 GMC?

Repairing this code may involve replacing the faulty start indicator control module, repairing any damaged wiring in the circuit, or addressing any issues with the ignition switch as needed.

5. Can OBDII code B0977 GMC be fixed at home, or do I need professional help?

Depending on your level of automotive expertise and access to the necessary tools, you may be able to address this code at home. However, if you are unsure about diagnosing or repairing the issue, it is recommended to seek professional help.

6. Is it safe to continue driving with OBDII code B0977 GMC present?

It is not recommended to continue driving with this code present, as it can lead to potential issues with starting the vehicle or affect the overall performance of the ignition system.

7. How do I reset OBDII code B0977 GMC after making repairs?

After making the necessary repairs, you can reset the code using a scan tool to clear the error codes stored in the vehicle's computer system.

8. Are there any preventive measures to avoid OBDII code B0977 GMC in the future?

To prevent this code from reoccurring, it is advisable to conduct regular maintenance checks on the vehicle's ignition system, ensure proper wiring connections, and address any warning signs promptly.

9. Can extreme weather conditions affect OBDII code B0977 GMC?

Extreme weather conditions, such as excessive heat or moisture, can potentially impact the start indicator control circuit and lead to the triggering of this OBDII code.

10. How long does it typically take to repair OBDII code B0977 GMC?

The repair time for this code can vary depending on the exact cause of the issue, the availability of replacement parts, and your level of experience with automotive repairs. It is recommended to allocate sufficient time to diagnose and address the problem effectively.