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2020 Sierra 1500 Battery Drain & "Service Charging System" Warning

0

Angela R. · rep 0 · May 22, 3:42 AM · 1 replies · solved · Question

Vehicle: 2020 GMC Sierra 1500 SLT

Hey everyone,

I've got a frustrating issue with my 2020 GMC Sierra 1500 SLT. For the past few weeks, the battery keeps dying overnight if I don't drive it daily. I've had to jump it several times, and it's getting old.

Yesterday, after jumping it, the "Service Charging System" message popped up on the dash. The battery is only about a year old, so I'm wondering if it's something else. Could it be the alternator, or maybe a parasitic draw I'm not aware of?

Any ideas on what I should check first? I'm trying to avoid an expensive trip to the dealership if it's something simple.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:42 AM

0

ClearTheCode admin answer:

It sounds like you're dealing with a classic charging system issue, potentially compounded by a parasitic draw. The "Service Charging System" message strongly points to the alternator or related components.

Here's a breakdown of potential causes and steps:

  1. Check Battery Health: Even if it's a year old, a repeatedly drained battery can be damaged. Have it load tested at an auto parts store. A weak battery can mimic other problems.
  2. Alternator Output Test: The primary suspect for a "Service Charging System" light. A failing alternator won't adequately recharge the battery. Most auto parts stores can test your alternator while it's still on the vehicle.
    • Common OBD-II Codes: P0562 (System Voltage Low), P0622 (Generator Field F Control Circuit Malfunction).
  3. Parasitic Draw Test: If the battery is good and the alternator tests fine, something is drawing power when the truck is off. This requires a multimeter and patience:
    • Connect a multimeter in series between the negative battery post and the negative battery cable.
    • Wait for all modules to 'sleep' (can take 15-30 minutes).
    • A draw over 50mA (0.05A) is usually excessive. Pull fuses one by one until the draw drops to identify the circuit.
  4. Wiring and Connections: Inspect battery terminals, alternator connections, and ground straps for corrosion or looseness. A poor connection can impede charging.

When to See a Shop:

  • If the alternator tests bad, replacement is usually straightforward but can be labor-intensive. A professional can ensure proper installation and check for underlying causes.
  • If you identify a parasitic draw but can't pinpoint the exact component on the circuit, a shop with advanced diagnostic tools can help trace it.
  • If the issue persists after checking the battery and alternator, or if you're uncomfortable performing electrical tests, a certified technician can diagnose the complex electrical system of your Sierra.
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