AutoCodes – RAM – B21F8 RAM

B21F8 RAM Code - Exterior Lighting Power Supply Input 1 Circuit Open

Quick Answer

The Body Control Module (BCM) monitors the Exterior Lighting Power Supply Input 1 Circuit. Common causes include Blown Exterior Lighting Fuse, Exterior Lighting Fuse harness is open or shorted, Exterior Lighting Fuse 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: B21F8 RAM indicates Exterior Lighting Power Supply Input 1 Circuit Open.
Common causes: Common causes include Blown Exterior Lighting Fuse, Exterior Lighting Fuse harness is open or shorted, Exterior Lighting Fuse 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 1,582

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 30, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B21F8 RAM Description

The Body Control Module (BCM) monitors the Exterior Lighting Power Supply Input 1 Circuit. The BCM sets the OBDII code when it detects less than 1.0 volt on the Fused B(+) circuit.

OBDII Code B21F8 RAM - Exterior Lighting Power Supply Input 1 Circuit Open - AutoCodes.com — B21F8 RAM Code - Exterior Lighting Power Supply Input 1 Circuit Open

What does this mean?

What are the Possible Causes of the DTC B21F8 RAM?

Blown Exterior Lighting Fuse
Exterior Lighting Fuse harness is open or shorted
Exterior Lighting Fuse circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC B21F8 RAM?

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 B21F8 RAM 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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Need Help with the Code?

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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 B21F8 RAM Code

1. What are the common symptoms of OBDII code B21F8 RAM related to Exterior Lighting Power Supply Input 1 Circuit Open?

The common symptoms include exterior lights not working, flickering lights, or lights staying on constantly.

2. What are the possible causes of OBDII code B21F8 RAM indicating an Exterior Lighting Power Supply Input 1 Circuit Open?

Possible causes include a damaged wiring harness, a faulty lighting control module, or a blown fuse related to the exterior lighting system.

3. How can I diagnose the issue of Exterior Lighting Power Supply Input 1 Circuit Open associated with OBDII code B21F8 RAM?

To diagnose the problem, you can use a multimeter to check for continuity in the wiring, inspect the exterior lighting components for damage, and scan the vehicle's computer for specific fault codes.

4. Is it safe to continue driving with OBDII code B21F8 RAM triggered by an Exterior Lighting Power Supply Input 1 Circuit Open?

It is not recommended to continue driving with this code active, as it can affect the visibility of your vehicle and compromise safety on the road.

5. How can I reset OBDII code B21F8 RAM for Exterior Lighting Power Supply Input 1 Circuit Open?

Resetting the code can be done using an OBDII scanner or by disconnecting the car's battery for a few minutes to clear the fault code.

6. Can a DIY enthusiast repair OBDII code B21F8 RAM for Exterior Lighting Power Supply Input 1 Circuit Open?

Depending on the exact cause, some DIY repairs may be possible, such as checking and replacing fuses or repairing damaged wiring. However, complex issues may require professional assistance.

7. What are the potential repair tips for resolving OBDII code B21F8 RAM related to Exterior Lighting Power Supply Input 1 Circuit Open?

Repair tips include checking and replacing any damaged wiring, ensuring proper connections, inspecting the lighting control module, and verifying the functionality of related components.

8. How much does it typically cost to repair OBDII code B21F8 RAM for Exterior Lighting Power Supply Input 1 Circuit Open?

The cost of repair can vary depending on the exact cause of the issue and labor rates in your area. It is recommended to obtain quotes from multiple mechanics or service centers.

9. Are there any preventative measures to avoid OBDII code B21F8 RAM for Exterior Lighting Power Supply Input 1 Circuit Open?

Regularly inspecting the exterior lighting system for any signs of damage, ensuring proper connections, and addressing any electrical issues promptly can help prevent this code from occurring.

10. Can OBDII code B21F8 RAM for Exterior Lighting Power Supply Input 1 Circuit Open affect the overall performance of my vehicle?

While this code primarily relates to the exterior lighting system, unresolved electrical issues can potentially impact other vehicle systems over time. It is best to address the issue promptly to avoid further complications.