The largest online repair guide library for every car

About us
Contact support
FAQ
Sign up
Sign in

2019 CT6 Battery Draining Overnight - Parasitic Draw?

0

Mike T. · rep 0 · May 25, 2:49 AM · 1 replies · solved · Question

Vehicle: 2019 Cadillac CT6 2.0T

Hello fellow Cadillac owners,

I'm having a persistent and annoying problem with my 2019 Cadillac CT6, 2.0T. The battery keeps dying overnight. I've replaced the battery twice in the last six months, thinking it was just a bad battery, but the issue persists. Each morning, it's completely dead and needs a jump.

I've checked all the obvious things: no interior lights left on, no doors ajar, trunk closed properly. The car doesn't show any active Check Engine Lights or other warnings on the dash. It starts fine after a jump, but by morning, it's completely flat.

This sounds like a parasitic draw to me. Has anyone with a CT6 experienced this, and if so, what was the culprit? I'm dreading taking it to the dealership only for them to spend hours tracking down a ghost.

Any tips on how to diagnose this myself or common problem areas for parasitic draws on these cars would be greatly appreciated!

Thanks!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:49 AM

0

ClearTheCode admin answer:

A battery draining overnight on your 2019 Cadillac CT6, especially after multiple battery replacements, is a classic symptom of a parasitic draw. This means something in the vehicle is consuming power even when the car is turned off and locked. Modern vehicles with complex electronics are particularly susceptible to this.

Common Causes of Parasitic Draw:

  1. Faulty Modules: A control module (e.g., infotainment, telematics, body control module, door module) that fails to 'go to sleep' or is stuck in an active state.
  2. Aftermarket Accessories: Incorrectly installed aftermarket alarms, stereo systems, dash cams, or GPS trackers can often cause draws.
  3. Stuck Relays: A relay that remains energized when it shouldn't can keep a circuit active.
  4. Interior/Trunk Lights: Even if you think they're off, a faulty switch or sensor could be keeping a light on at a low level, or the trunk light could be staying on.
  5. Glove Box/Vanity Mirror Lights: Often overlooked, these small lights can cause a significant draw over time.
  6. Faulty Alternator Diode: A failing diode in the alternator can allow current to flow back to the alternator when the engine is off, draining the battery.

Diagnostic Steps (Requires a Multimeter):

  1. Charge Battery Fully: Ensure the battery is fully charged before starting.
  2. Connect Multimeter: Disconnect the negative battery terminal. Connect your multimeter in series between the negative battery post and the disconnected negative battery cable. Set the multimeter to measure Amps (start with a high range, like 10A, then switch to mA once a stable reading is achieved).
  3. Allow Vehicle to 'Sleep': Close all doors, trunk, hood (you may need to latch the hood switch to simulate closure), and lock the vehicle. Wait at least 20-30 minutes for all modules to power down. A normal draw should be around 20-50 mA (0.02-0.05 Amps). Anything significantly higher indicates a draw.
  4. Pull Fuses One by One: Once you have a stable, high draw reading, start pulling fuses from the fuse box (both under the hood and inside the cabin) one at a time. Watch the multimeter. When the amperage drops significantly, you've found the circuit with the draw. This narrows down the problem area.
  5. Isolate Component: Once the circuit is identified, consult your vehicle's wiring diagram to see which components are on that circuit. You can then disconnect individual components on that circuit to find the culprit.

When to See a Shop:

  • If you're uncomfortable working with electrical systems or using a multimeter.
  • If you've pulled all fuses and still have a significant draw, suggesting an issue with the alternator or a main power feed not on a fused circuit.
  • If the draw is on a complex circuit with many components (e.g., infotainment, body control module), as further diagnosis might require specialized GM diagnostic tools (like MDI) to communicate with individual modules and identify which one is staying awake.
Menu

Help & account