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2017 XC90 T6 - Persistent Battery Drain and Start/Stop Malfunction

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Mike T. · rep 0 · May 25, 3:55 AM · 1 replies · solved · Question

Vehicle: 2017 Volvo XC90 T6 Inscription

My 2017 Volvo XC90 T6 Inscription has been having issues with battery drain. If I leave it for more than a day, the battery is completely dead. I've had it jumped multiple times, which is getting old quickly.

Also, the start/stop function rarely works anymore, even on long drives or after the battery has been fully charged. I replaced the main battery and the auxiliary battery about 6 months ago, thinking that would solve it, but the problem persists. I'm at my wit's end trying to figure out what's causing this constant drain.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:55 AM

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ClearTheCode admin answer:

Persistent battery drain, especially after replacing both batteries, points towards a parasitic draw. This means a component or module is staying awake and consuming power even when the vehicle is off.

  1. Check for Parasitic Draw: A professional shop or an advanced DIYer can perform a parasitic draw test using a multimeter. This involves measuring the current draw from the battery with the car off and all systems asleep. A healthy draw is typically under 50mA.
  2. Identify the Culprit Module: If the draw is high, the next step is to pull fuses one by one while monitoring the multimeter. When the draw drops significantly, the circuit associated with that fuse is where the problem lies. Common culprits in Volvo XC90s can include:
    • Infotainment system (Sensus)
    • Keyless entry module
    • Tailgate module
    • Climate control module
    • Battery Management System (BMS) sensor itself (though less common)
  3. Alternator Check: While less likely given new batteries, a failing alternator that isn't properly charging the battery can mimic drain issues. Have its output tested.
  4. Software Updates: Sometimes, module software glitches can cause them to not enter sleep mode correctly. Ensure all vehicle software is up to date at a Volvo dealership.

Causes:

  • Faulty electronic module not shutting down (e.g., infotainment, telematics, keyless entry).
  • Wiring short or component staying active (e.g., glove box light, trunk light).
  • Defective Battery Management System (BMS) sensor providing incorrect readings.
  • Faulty alternator preventing full charge.

When to See a Shop: If you're not comfortable performing electrical diagnostics with a multimeter, or if the parasitic draw test identifies a complex module as the culprit, it's best to visit a Volvo specialist or dealership. They have diagnostic tools (VIDA) that can communicate with individual modules, read fault codes (e.g., P0562 - System Voltage Low), and pinpoint the exact source of the draw, often saving time and preventing further damage.

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