AutoCodes – Pontiac – B3840 Pontiac

B3840 Pontiac Code - Park Lamp Signal Circuit Low

Quick Answer

The Body Control Module (BCM) monitors the activity of the park lamp relay switch with the headlamp switch in either the PARK position or the HEAD position. Common causes include Faulty Park Lamp Relay, Park Lamp Relay harness is open or shorted, Park Lamp Relay 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: B3840 Pontiac indicates Park Lamp Signal Circuit Low.
Common causes: Common causes include Faulty Park Lamp Relay, Park Lamp Relay harness is open or shorted, Park Lamp Relay 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 479

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 23, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B3840 Pontiac Description

The Body Control Module (BCM) monitors the activity of the park lamp relay switch with the headlamp switch in either the PARK position or the HEAD position. The Diagnostic Trouble Code (DTC) sets when the BCM detects an open or a short to ground in the park lamp supply voltage circuit with the headlamp switch in either the PARK position or the HEAD position.

OBDII Code B3840 Pontiac - Park Lamp Signal Circuit Low - AutoCodes.com — B3840 Pontiac Code - Park Lamp Signal Circuit Low

What does this mean?

What are the Possible Causes of the DTC B3840 Pontiac?

Faulty Park Lamp Relay
Park Lamp Relay harness is open or shorted
Park Lamp Relay circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC B3840 Pontiac?

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 B3840 Pontiac 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 B3840 Pontiac code?

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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 B3840 Pontiac Code

1. What does the OBDII code B3840 mean for a Pontiac?

B3840 indicates a "Park Lamp Signal Circuit Low," meaning the park lamp circuit is experiencing low voltage or an open/short condition.

2. What are the common symptoms of code B3840 on a Pontiac?

Symptoms may include malfunctioning or dim park lamps, dashboard warning lights, or issues with exterior lighting.

3. What causes the B3840 code to be triggered?

Common causes include a faulty park lamp relay, damaged wiring or connectors, a blown fuse, or a malfunctioning body control module (BCM).

4. Can a blown fuse cause the B3840 code?

Yes, a blown fuse in the park lamp circuit can cause low voltage and trigger the B3840 code.

5. How can I diagnose the B3840 code on my Pontiac?

Start by inspecting the park lamp circuit wiring, connectors, and fuses for damage. Use a multimeter to check for proper voltage and continuity.

6. How do I fix the B3840 code on my Pontiac?

Repairs may involve replacing damaged wiring, repairing connectors, replacing a blown fuse, or replacing a faulty park lamp relay.

7. Is the B3840 code serious?

While it may not immediately affect vehicle performance, unresolved issues with the park lamp circuit can lead to safety concerns, especially during nighttime driving.

8. Can a faulty body control module (BCM) cause the B3840 code?

Yes, a malfunctioning BCM can fail to properly control the park lamp circuit, resulting in the B3840 code.

9. Do I need to reprogram the BCM after replacing it for the B3840 code?

In most cases, BCM replacement requires reprogramming to ensure proper functionality. Consult a professional technician for assistance.

10. Can I drive my Pontiac with the B3840 code active?

While the vehicle may remain drivable, itâ€™s not recommended to ignore this code, as it can compromise visibility and safety due to malfunctioning exterior lights.