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2018 Ram 1500 Laramie - Battery Draining Overnight, No Obvious Cause

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Robert C. · rep 0 · May 22, 3:33 AM · 1 replies · solved · Question

Vehicle: 2018 Ram 1500 Laramie

Hey everyone,

I'm having a really frustrating issue with my 2018 Ram 1500 Laramie. For the past few weeks, if I leave it parked overnight, the battery is completely dead by morning. I've checked all the lights, radio, and accessories, and nothing seems to be left on.

I had the battery tested, and it's good. The alternator also seems to be charging fine when the truck is running. It's like something is drawing power even when the truck is off. Has anyone experienced this with their Ram? Any ideas on what could be causing a parasitic draw?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:33 AM

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ClearTheCode admin answer:

Battery drain, or parasitic draw, is a common issue that can be tricky to diagnose. It occurs when an electrical component continues to draw power from the battery even after the vehicle is turned off.

Common Causes:

  1. Faulty Modules: Control modules (e.g., radio, navigation, body control module) can sometimes fail to enter 'sleep' mode, continuously drawing power.
  2. Aftermarket Accessories: Improperly installed aftermarket stereos, alarms, remote starters, or other accessories are frequent culprits.
  3. Stuck Relays: A relay that is stuck in the 'on' position can keep a circuit active.
  4. Short Circuits: A short to ground in a wiring harness can cause a constant draw.
  5. Glove Box/Under Hood Lights: Small lights that remain on due to a faulty switch.

Troubleshooting Steps:

  1. Perform a Parasitic Draw Test: Using a multimeter, connect it in series between the negative battery post and the negative battery cable. With the vehicle off and all doors closed (wait 10-20 minutes for modules to 'sleep'), observe the amperage draw. A healthy draw is typically under 50 milliamps (0.05 amps). If it's higher, proceed to step 2.
  2. Pull Fuses One by One: While monitoring the multimeter, systematically pull fuses from the fuse box (both under the hood and inside the cabin) until the draw significantly drops. This will help isolate the circuit causing the problem.
  3. Check for OBD Codes: While a parasitic draw doesn't always trigger a specific OBD code, a faulty module might log a 'U' code (network communication) or 'B' code (body electrical) that could point to the problematic system.

When to See a Shop: If you're uncomfortable performing electrical diagnostics or cannot pinpoint the source of the draw, it's best to take your Ram to a qualified automotive electrical specialist. They have advanced diagnostic tools and experience to trace complex electrical issues and ensure proper repair without damaging sensitive electronic components.

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