AutoCodes – Generic – B1556

B1556 Code - Ignition Run/Start Circuit Open

Quick Answer

The Body Control Module (BCM) monitors the Ignition Switch. 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: B1556 indicates Ignition Run/Start Circuit Open.
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 8,853

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 May 02, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B1556 Description

The Body Control Module (BCM) monitors the Ignition Switch. The BCM sets the OBDII code when the Ignition Switch is not to factory specifications.

OBDII Code B1556 - Ignition Run/Start Circuit Open - AutoCodes.com — B1556 Code - Ignition Run/Start Circuit Open

What does this mean?

What are the Possible Causes of the DTC B1556?

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 B1556?

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 B1556 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 B1556 code?

Need more information on how to fix the B1556 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B1556 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

B1556 Buick — Odometer Mileage & EEPROM Disagree
B1556 Cadillac — Odometer Mileage & EEPROM Disagree
B1556 Chevrolet — Odometer Mileage & EEPROM Disagree
B1556 GMC — Odometer Mileage & EEPROM Disagree

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 B1556 Code

1. What are the common symptoms of OBDII code B1556 (Ignition Run/Start Circuit Open)?

The common symptoms include difficulty starting the vehicle, the engine not turning over, and the ignition system failing to engage.

2. What are the possible causes of OBDII code B1556?

Possible causes of this code include a faulty ignition switch, damaged wiring in the ignition circuit, a blown fuse, or a malfunctioning ignition relay.

3. How can I diagnose the source of OBDII code B1556?

To diagnose the issue, you can use a diagnostic scanner to retrieve the trouble codes, visually inspect the ignition system components for damage, and perform continuity tests on the wiring in the ignition circuit.

4. Can OBDII code B1556 be fixed by resetting the engine light?

Resetting the engine light may temporarily clear the code, but it will not fix the underlying issue causing the Ignition Run/Start Circuit Open problem. Proper diagnosis and repair are required.

5. Is it safe to continue driving with OBDII code B1556 present?

It is not recommended to continue driving with this code present, as it can lead to sudden stalling or failure to start the vehicle, potentially leaving you stranded.

6. How much does it typically cost to repair OBDII code B1556?

The cost of repairing this code can vary depending on the underlying cause. It may range from a simple fuse replacement costing a few dollars to more extensive repairs involving the ignition switch or wiring, which can cost a few hundred dollars.

7. Can I repair OBDII code B1556 myself, or should I seek professional help?

If you have experience working with automotive electrical systems, you may be able to diagnose and repair this code yourself. However, if you are unsure or unfamiliar with electrical repairs, it is best to seek professional help to avoid causing further damage.

8. What are some tips to prevent OBDII code B1556 from occurring?

Regularly inspecting the ignition system components for wear or damage, avoiding overloading the electrical system, and addressing any minor issues promptly can help prevent this code from occurring.

9. Will OBDII code B1556 affect my vehicle's performance?

Yes, this code can affect your vehicle's performance by preventing it from starting or causing intermittent stalling, which can impact your driving experience and safety.

10. How long does it typically take to repair OBDII code B1556?

The repair time for this code can vary depending on the cause and complexity of the issue. Simple fixes like replacing a fuse may take less than an hour, while more involved repairs may require several hours or even a full day at a repair shop.