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2018 MKX Intermittent No-Start & Electrical Glitches

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Nicole W. · rep 0 · May 22, 6:07 AM · 1 replies · solved · Question

Vehicle: 2018 Lincoln MKX Reserve

Hey everyone, hoping someone here has experienced something similar. My 2018 Lincoln MKX Reserve has been having intermittent starting issues for the past few weeks. Sometimes it starts perfectly fine, but other times, I turn the key and get absolutely nothing – no crank, just a click, or sometimes it cranks weakly but won't catch.

When it acts up, I also notice the dash lights flickering erratically, and the infotainment screen sometimes freezes or goes black for a second. It's really frustrating and unpredictable.

I've already had the battery tested at two different places, and both said it's good and holding a charge. The terminals look clean and tight. Could this be a deeper electrical problem, maybe a module or a ground issue? Any ideas on what to check next before I take it to the dealership?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 6:07 AM

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ClearTheCode admin answer:

Intermittent no-start conditions combined with electrical glitches in your 2018 Lincoln MKX Reserve often point beyond a simple battery issue, even if the battery tests good. This behavior suggests a potential problem with the charging system, a critical electrical connection, or a control module.

Here's a diagnostic approach:

  1. Inspect Battery Cables and Ground Points: Even if terminals look clean, thoroughly inspect the entire length of both positive and negative battery cables for any signs of corrosion, fraying, or loose connections, especially where the negative cable connects to the chassis and engine block. A poor ground connection can cause a myriad of electrical gremlins.
  2. Check Alternator Output: While the car is running (if you can get it to start), use a multimeter to check the voltage across the battery terminals. It should be consistently between 13.5V and 14.5V. Fluctuations or readings outside this range could indicate a failing alternator or voltage regulator.
  3. Look for Parasitic Draw: An electrical component staying on when the car is off can slowly drain the battery, leading to intermittent no-starts. This requires a multimeter and patience to test each circuit by pulling fuses.
  4. Scan for Diagnostic Trouble Codes (DTCs): Even without a "Check Engine" light, a professional-grade OBD-II scanner can often reveal 'pending' or 'history' codes related to communication issues or module faults. Look for codes like:
    • U0100: Lost Communication with Engine Control Module/Powertrain Control Module (ECM/PCM)
    • U0140: Lost Communication With Body Control Module (BCM)
    • B10A2: Battery Voltage Sensor Circuit
    • P0620: Generator Control Circuit Malfunction

Potential Causes:

  • Loose or Corroded Ground Wires: The most common culprit for intermittent electrical issues.
  • Failing Alternator/Voltage Regulator: Can cause undercharging or overcharging, leading to battery and module issues.
  • Body Control Module (BCM) or Powertrain Control Module (PCM) Malfunction: These modules control many electrical functions, and a fault can cause widespread symptoms.
  • Faulty Ignition Switch or Starter Relay: Less common but can cause no-start conditions.

When to See a Shop: If you've checked the basic connections and the alternator, and especially if you're getting communication-related OBD codes (U-codes), it's best to take your MKX to a qualified technician. Diagnosing module-related issues or complex wiring problems requires specialized tools and expertise to avoid further damage.

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