The largest online repair guide library for every car

About us
Contact support
FAQ
Sign up
Sign in

2020 Wrangler JL Battery Drains Overnight - Electrical Issue?

0

Chris P. · rep 0 · May 24, 1:26 PM · 1 replies · solved · Question

Vehicle: 2020 Jeep Wrangler JL Sahara

Hey everyone, I'm having a super frustrating issue with my 2020 Jeep Wrangler JL Sahara. For the past few weeks, if I leave it parked overnight, the battery is completely dead by morning. I've had to jump-start it almost every day.

It's not the original battery; I replaced it about 6 months ago, and I've had it tested – it's good. I've also checked for obvious lights left on, like the glove box or dome lights, and everything seems off. I don't have any aftermarket accessories wired directly to the battery, just a dash cam that plugs into a switched outlet.

Could this be a parasitic draw, or is there a known issue with the electrical system on these JLs? It's really inconvenient, and I'm worried about damaging other components. Any ideas what could be draining it so quickly?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 24, 1:26 PM

0

ClearTheCode admin answer:

This sounds like a classic case of a parasitic draw, which is a common electrical problem where a component or system continues to draw power from the battery even when the vehicle is turned off. Here's how to approach it:

  1. Check for Obvious Draws: Before diving into complex diagnostics, double-check all interior lights (including glove box, console, vanity mirrors), under-hood light, and ensure all doors, the tailgate, and the hood are fully closed and latched. Sometimes a faulty door switch can keep a module awake.

  2. Perform a Parasitic Draw Test:

    • Ensure all accessories are off, doors are closed (you might need to trick the latch with a screwdriver), and the vehicle has been off for at least 15-30 minutes to allow all modules to 'go to sleep'.
    • Disconnect the negative battery cable.
    • Connect a multimeter in series between the negative battery post and the negative battery cable. Set the multimeter to measure amperage (at least 10A range initially).
    • A normal draw is typically under 50mA (0.05 amps). If you see a higher reading, you have a draw.

  3. Isolate the Circuit: Once a high draw is confirmed, start systematically pulling fuses from the fuse box (both under the hood and inside the cabin) one by one while monitoring the multimeter. When the draw drops significantly, the last fuse pulled indicates the problematic circuit.

  4. Common Culprits in Jeep Wranglers (JL):

    • Uconnect System: Software glitches or a module staying awake can cause a drain. Try a soft reset of the Uconnect system if possible.
    • Engine Stop-Start (ESS) System: Issues with the auxiliary battery or related modules can lead to unexpected drains, as the system constantly monitors battery health.
    • Faulty Modules: A Body Control Module (BCM), Totally Integrated Power Module (TIPM), or other control modules failing to enter sleep mode.
    • Aftermarket Accessories: Even if plugged into a switched outlet, some dash cams or chargers can have a small constant draw or wake up modules. Disconnect your dash cam completely for a test period.

  5. OBD Codes: While a parasitic draw itself doesn't always throw a specific code directly, persistent low voltage from battery drain can trigger codes like:

    • P0562: System Voltage Low
    • U0401: Invalid Data Received from ECM/PCM A (or other module communication codes due to low voltage)

  6. When to See a Shop: If you're uncomfortable performing a parasitic draw test, or if you've identified a circuit but can't pinpoint the exact component, it's best to take your Wrangler to a qualified Jeep dealership or an automotive electrical specialist. They have advanced diagnostic tools (like a scan tool with sleep mode monitoring) to trace complex electrical issues and can perform software updates for modules that might be causing the problem.

Menu

Help & account