AutoCodes – Cadillac – B3840 Cadillac

B3840 Cadillac 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 Cadillac 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 429

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

What does this mean?

What are the Possible Causes of the DTC B3840 Cadillac?

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 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B3840 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 B3840 Cadillac Code

1. What are the common symptoms of OBDII code B3840 Cadillac (Park Lamp Signal Circuit Low)?

- The common symptoms may include dim or non-functioning park lamps, dashboard warning lights, and potential issues with turn signals.

2. What are the possible causes of the OBDII code B3840 Cadillac?

- The code B3840 Cadillac typically indicates a malfunction in the park lamp signal circuit, which could be caused by a faulty wiring harness, a defective park lamp switch, or a blown fuse.

3. How can I diagnose the OBDII code B3840 Cadillac issue?

- To diagnose the issue, you can start by checking the park lamp bulbs, inspecting the wiring for any visible damage, and testing the park lamp switch for proper functionality using a multimeter.

4. What are some repair tips for fixing the OBDII code B3840 Cadillac?

- Repair tips may include replacing any faulty park lamp bulbs, repairing or replacing damaged wiring, checking and replacing fuses if necessary, and testing the park lamp switch for continuity.

5. Can I drive my Cadillac with the OBDII code B3840 present?

- It is generally not recommended to drive your Cadillac with the B3840 code present, as it indicates a potential issue with the park lamp signal circuit that may affect the safety and functionality of your vehicle.

6. How much does it typically cost to repair the OBDII code B3840 Cadillac?

- The cost of repairing the B3840 code can vary depending on the specific cause of the issue, but it may range from a simple bulb replacement to more extensive wiring repairs, potentially costing between $50 to $200 or more.

7. Is it possible to reset the OBDII code B3840 Cadillac without fixing the underlying issue?

- While you can clear the code temporarily using an OBDII scanner, it is important to address the root cause of the problem to prevent the code from reappearing and ensure the proper functioning of your vehicle's park lamp system.