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2020 Ram 2500 Battery Drain & "Service Electronic Throttle Control" Warning

0

Mike T. · rep 0 · May 25, 2:31 AM · 1 replies · solved · Question

Vehicle: 2020 Ram 2500 Big Horn

Hi all,

I've got a problem with my 2020 Ram 2500 Big Horn (6.4L Hemi). For the past few weeks, if I leave it parked for more than a day, the battery is completely dead. I've had to jump-start it multiple times. I replaced the main battery thinking that was the issue, but it's still happening.

After a jump and getting it running, I occasionally get a "Service Electronic Throttle Control" warning light on the dash, and sometimes the truck goes into limp mode. Turning the truck off and on usually clears the throttle warning, but the battery drain is constant. Could these issues be related? I'm stumped on what could be drawing so much power.

Any ideas on where to start looking? Thanks in advance!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:31 AM

0

ClearTheCode admin answer:

Battery drain and intermittent electronic throttle control (ETC) warnings can indeed be related, often pointing to underlying electrical system issues or a faulty module. A low voltage condition can cause various modules to malfunction, triggering seemingly unrelated warnings.

Common Causes:

  1. Parasitic Draw: A component or module is staying awake and drawing power even when the vehicle is off. Common culprits include:
    • Faulty infotainment system (Uconnect)
    • Aftermarket accessories wired incorrectly
    • Stuck relays
    • Body Control Module (BCM) issues
  2. Failing Alternator: While less likely to cause a parasitic draw, a weak alternator might not be fully charging the battery, leading to low voltage conditions that trigger warnings and leave the battery depleted.
  3. Faulty Battery Sensor: Modern Rams often have an Intelligent Battery Sensor (IBS) on the negative battery terminal. If this sensor fails, it can mismanage charging or report incorrect battery status, leading to undercharging or overcharging issues.
  4. Throttle Body/Pedal Position Sensor: While the ETC warning can be triggered by low voltage, a direct fault with the throttle body or accelerator pedal position sensor can also be the primary cause.

Troubleshooting Steps:

  1. Perform a Parasitic Draw Test: This involves using a multimeter to measure current draw from the battery with the vehicle off. Systematically pull fuses one by one until the draw drops to an acceptable level (typically under 50mA). This helps isolate the circuit causing the drain.
  2. Check Alternator Output: With the engine running, measure the voltage across the battery terminals. It should be between 13.5V and 14.7V. If it's significantly lower, the alternator may be failing.
  3. Scan for Diagnostic Trouble Codes (DTCs): Use an OBD-II scanner to check for codes. For battery drain, look for codes related to modules staying awake (e.g., U-codes). For the ETC warning, common codes include:
    • P2118: Throttle Actuator Control Motor Current Range/Performance
    • P2101: Throttle Actuator Control Motor Circuit Range/Performance
    • P0121: Throttle/Pedal Position Sensor/Switch 'A' Circuit Range/Performance
  4. Inspect Battery Sensor (IBS): Visually inspect the sensor on the negative battery cable for any signs of damage or corrosion.

When to See a Shop:

  • If you're unable to perform the parasitic draw test accurately or identify the source.
  • If the alternator output is consistently low, indicating a charging system problem.
  • If diagnostic codes point to specific module failures or throttle body issues that require specialized tools for diagnosis or replacement.
  • If the issue persists after basic checks, as it may involve complex wiring or module diagnostics.
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