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2020 Atlas Tail Light Intermittent Failure - Left Side

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Mike T. · rep 0 · May 25, 3:21 AM · 1 replies · solved · Question

Vehicle: 2020 Volkswagen Atlas SEL Premium

I'm having a weird issue with the left tail light on my 2020 Volkswagen Atlas SEL Premium. Sometimes it works perfectly, but other times, the brake light and turn signal on that side just stop working. The running light usually stays on, but the brighter brake light and the amber turn signal go out. I get a 'Left Rear Light Malfunction' warning on the dash.

Jiggling the wiring harness sometimes brings it back temporarily. I've checked the bulbs (they look fine, and it's LED anyway for the brake/turn) and the fuse for the tail lights, but everything seems okay. Could this be a bad connection, a faulty wiring harness, or something more serious like the Body Control Module (BCM)?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:21 AM

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ClearTheCode admin answer:

Intermittent tail light failure, especially with a specific warning on the dash, points to an electrical fault within the circuit for your 2020 Volkswagen Atlas. Here's what to consider:

  1. Wiring Harness/Connector Issues:

    • The most likely culprit, especially since jiggling wires temporarily resolves it. Inspect the wiring harness leading to the left tail light assembly. Look for frayed wires, pinched sections, or corrosion within the connector itself (both on the tail light assembly and the vehicle side).
    • Water intrusion into the tail light housing or connector is a common cause of corrosion.

  2. Tail Light Assembly Fault:

    • Even though it's an LED unit, the entire assembly can fail. There might be an internal fault with the LED array or the circuit board within the housing. Sometimes, a cold solder joint can cause intermittent operation.

  3. Ground Connection:

    • A poor ground connection for the tail light can cause erratic behavior. Ensure the ground wire and its connection point are clean and secure.

  4. Body Control Module (BCM) / Central Electronics Control Unit (J519):

    • The BCM controls many exterior lights. If the BCM's output for that specific tail light circuit is intermittently failing, it could cause this issue. However, this is less common than wiring or assembly issues and usually presents with other electrical problems.

Potential OBD Codes: While a generic OBD-II scanner might not show specific codes for a light malfunction, a VW-specific diagnostic tool (like VCDS) would likely show fault codes in the Central Electronics Control Unit (J519) module, such as "01504 - Bulb for Brake Lights; Left - Electrical Fault in Circuit" or similar, indicating a problem with the specific light circuit.

When to See a Shop: If a thorough visual inspection of the wiring and connectors doesn't reveal the fault, or if you suspect an internal issue with the LED tail light assembly or the BCM, it's best to take your Atlas to a Volkswagen dealership or an independent specialist. They can perform advanced diagnostics, test the circuit's integrity, and determine if the tail light assembly or a more complex module replacement is needed.

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