AutoCodes – Cadillac – B3884 Cadillac

B3884 Cadillac Code - Center High Mounted Stop Lamp Circuit

Quick Answer

The brake pedal position sensor is used to sense the action of the driver's application of the brake pedal. Common causes include Faulty Center High Mounted Stop Lamp, Center High Mounted Stop Lamp harness is open or shorted, Center High Mounted Stop Lamp 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: B3884 Cadillac indicates Center High Mounted Stop Lamp Circuit.
Common causes: Common causes include Faulty Center High Mounted Stop Lamp, Center High Mounted Stop Lamp harness is open or shorted, Center High Mounted Stop Lamp 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 1,671

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 Jun 16, 2023

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code B3884 Cadillac Description

The brake pedal position sensor is used to sense the action of the driver's application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The Body Control Module (BCM) provides a low reference signal and a 5 V reference voltage to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM energizes the stop lamp relay by applying a voltage to the stop lamp relay control circuit. When the stop lamp relay is energized, the relay switch contacts close, and battery voltage is applied to the Center High Mounted Stop Lamp (CHMSL) control circuit which illuminates the CHMSL. The Diagnostic Trouble Code (DTC) will be set when the BCM detects a malfunction in the stop lamp relay control circuit.

OBDII Code B3884 Cadillac - Center High Mounted Stop Lamp Circuit - AutoCodes.com — B3884 Cadillac Code - Center High Mounted Stop Lamp Circuit

What does this mean?

What are the Possible Causes of the DTC B3884 Cadillac?

Faulty Center High Mounted Stop Lamp
Center High Mounted Stop Lamp harness is open or shorted
Center High Mounted Stop Lamp circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC B3884 Cadillac?

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 does this mean?

Code Tech Notes

B3884:01 Center High Mounted Stop Lamp Circuit Short to Battery
B3884:02 Center High Mounted Stop Lamp Circuit Short to Ground
B3884:04 Center High Mounted Stop Lamp Circuit Open

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B3884 Cadillac 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 B3884 Cadillac Code

1. What does the OBDII code B3884 mean on a Cadillac?

B3884 indicates an issue with the Center High Mounted Stop Lamp (CHMSL) circuit, typically involving a failure in the wiring, bulb, or associated components.

2. What are the symptoms of the B3884 code in a Cadillac?

Common symptoms include the center high-mounted brake light not working, a warning light on the dashboard, or other brake light functionality issues.

3. What causes the B3884 code to appear?

The B3884 code can be caused by a blown bulb, damaged wiring, a faulty CHMSL assembly, or a problem with the brake light control module.

4. Can I drive my Cadillac with the B3884 code?

Yes, but itâ€™s not recommended. The center high-mounted stop lamp is a safety feature, and driving without it may increase the risk of rear-end collisions.

5. How do I diagnose the B3884 code on a Cadillac?

Start by checking the CHMSL bulb for damage or burnout. Then inspect the wiring and connectors for signs of damage or corrosion. Use a multimeter to test for proper voltage at the lamp circuit.

6. How do I fix the B3884 code on my Cadillac?

Replace the CHMSL bulb if itâ€™s blown. Repair or replace damaged wiring, connectors, or the CHMSL assembly as necessary. If the issue persists, test the control module.

7. Does the B3884 code mean the brake light fuse is blown?

Not necessarily, but a blown fuse is one possible cause. Check the brake light fuse and replace it if itâ€™s blown.

8. How much does it cost to repair a B3884 code on a Cadillac?

Repair costs vary depending on the issue. Replacing a bulb may cost $10â€“$50, while repairing wiring or replacing the CHMSL assembly could range from $100â€“$300.

9. Can a faulty brake light switch trigger the B3884 code?

Itâ€™s unlikely but possible. The brake light switch typically controls all brake lights, so if other brake lights work, the issue is more likely isolated to the CHMSL circuit.

10. Will clearing the B3884 code fix the problem?

Clearing the code without addressing the underlying issue will not fix the problem. The code will likely return once the system detects the fault again.