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2018 Pacifica ESS System Not Working - Is This Normal?

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Sarah K. · rep 0 · May 22, 5:59 AM · 1 replies · solved · Question

Vehicle: 2018 Chrysler Pacifica Touring L

Hey everyone,

I've got a 2018 Chrysler Pacifica Touring L with about 60k miles, and lately, the Engine Stop/Start (ESS) system has been really inconsistent. Sometimes it works, sometimes it doesn't, and there's no clear pattern. I've noticed it's more likely not to work when it's cold outside, but it's also failed on warmer days.

The 'ESS OFF' light doesn't come on, and there are no warning lights on the dash. I'm just wondering if this is a common reliability issue with these vans, or if it's something I should be concerned about. I've heard about auxiliary battery problems, but I'm not sure how to check that.

Is there a known TSB or recall for this? Or is it just a quirk of the system? Any advice on what to look for or if I should take it to the dealer would be great. Thanks!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:59 AM

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This is a very common concern for Chrysler Pacifica owners, particularly with the ESS system. The inconsistency you're experiencing often points to specific underlying conditions that prevent the system from engaging.

Here's a breakdown of common causes and what to do:

  1. Auxiliary Battery Health: The most frequent culprit for ESS system malfunction in the Pacifica is a weak or failing auxiliary battery. The ESS system relies on a dedicated auxiliary battery (usually a smaller AGM battery located near the main battery or under the passenger seat) to power accessories when the engine is stopped. If this battery's charge or health drops below a certain threshold, the ESS system will disable itself to ensure reliable engine restarts.

    • Diagnosis: A dealership or a qualified independent shop can test the health of both your main and auxiliary batteries. A common diagnostic trouble code (DTC) related to battery issues, though not always directly for ESS, could be P0A80 (Replace Hybrid Battery Pack) or P0A94 (DC/DC Converter Performance), but often the ESS simply disables without a code if battery voltage is just low.

  2. Operating Conditions: The ESS system is designed to only activate under specific conditions to optimize performance and comfort. These include:

    • Engine temperature within a certain range.
    • Cabin temperature not requiring maximum A/C or heat.
    • Battery state of charge (both main and auxiliary) above a threshold.
    • Vehicle speed having exceeded a certain limit since the last stop.
    • Steering wheel not turned sharply.
    • Brake pedal pressure.
    • Hood closed.
    • Seatbelt fastened.
    • No active diagnostic trouble codes (DTCs) in the powertrain control module (PCM).

  3. Software Updates/TSBs: While less common for intermittent issues without codes, sometimes software glitches can affect ESS operation. It's worth checking with your Chrysler dealer if there are any outstanding Technical Service Bulletins (TSBs) or software updates for the ESS system or powertrain control module (PCM) for your 2018 Pacifica.

When to See a Shop:

  • If the issue is persistent and you suspect a battery problem, especially if your main battery is also getting old (3-5 years).
  • If you notice other electrical quirks (dimming lights, slow cranking).
  • If you want a definitive diagnosis of the auxiliary battery's health.
  • If you want to check for any relevant TSBs or software updates.

Addressing the auxiliary battery is usually the first step. It's a wear item and often needs replacement after a few years.

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