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2018 Discovery Sport Battery Drain Mystery - Help!

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Heather Y. · rep 0 · May 22, 6:32 AM · 1 replies · solved · Question

Vehicle: 2018 Land Rover Discovery Sport HSE

My 2018 Land Rover Discovery Sport HSE is driving me nuts. The battery keeps dying, sometimes overnight, sometimes after a couple of days. I've replaced the battery twice now, thinking it was just old, but the problem persists. It's incredibly frustrating to go out and find it completely dead.

I've noticed sometimes the infotainment screen takes a while to shut off, or I hear a faint clicking from the dash even after locking it. Could this be a parasitic draw? I'm worried about getting stranded.

Any ideas on what could be causing this or what I should check before taking it to the dealership? This is becoming a real headache.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 6:32 AM

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ClearTheCode admin answer:

Battery drain issues, often referred to as parasitic draws, are common and can be frustrating to diagnose. For your 2018 Land Rover Discovery Sport HSE, several electrical components could be responsible. Here's a breakdown of potential causes and steps:

  1. Verify Battery Health: Even new batteries can be faulty. Have your battery and charging system (alternator) professionally tested to rule out a simple component failure.

  2. Perform a Parasitic Draw Test:

    • Connect a multimeter in series between the negative battery post and the negative battery cable. Ensure all doors are closed, and the vehicle is fully 'asleep' (this can take 15-30 minutes for modern Land Rovers).
    • A normal draw is typically under 50 milliamps (0.05 amps). If it's significantly higher, you have a draw.
    • Start pulling fuses one by one, observing the multimeter. When the draw drops significantly, you've identified the circuit responsible.

  3. Common Land Rover Culprits for Parasitic Draw:

    • Infotainment System (ICTP/InControl Touch Pro): As you mentioned, if it's not shutting down properly, it can keep modules awake. Software glitches or a faulty head unit are possible.
    • Telematics Control Unit (TCU): This module handles emergency calls and connectivity. A malfunctioning TCU can prevent the vehicle from entering sleep mode.
    • Keyless Entry/Passive Entry Module: Faults here can keep the system active, constantly searching for a key.
    • HVAC Blower Motor Resistor: A failing resistor can cause the blower motor to run intermittently or not shut off completely.
    • Aftermarket Accessories: Any non-factory installed electronics (dash cams, alarms, etc.) can be a source if wired incorrectly.

  4. Diagnostic Trouble Codes (DTCs): While there isn't a single OBD code for 'parasitic draw,' a professional scan tool might reveal codes related to specific modules that are failing or not communicating, such as U0140 (Lost Communication With Body Control Module) or B10A2 (Battery Voltage Low), which could point to the root cause.

When to See a Shop: If your parasitic draw is high and you're unable to isolate the circuit using the fuse-pulling method, or if you suspect a specific module fault (especially with the infotainment or telematics), it's best to consult a Land Rover specialist. They have advanced diagnostic tools (like SDD or Topix JLR) that can communicate with individual modules, monitor their sleep status, and pinpoint the exact component causing the drain. Ignoring a persistent drain can lead to premature battery failure and potential damage to other electrical components.

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