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2018 Pacifica ESS Not Working - Battery or Something Else?

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David L. · rep 0 · May 22, 5:59 AM · 1 replies · solved · Question

Vehicle: 2018 Chrysler Pacifica Touring L

Hey everyone,

I'm having an issue with the Engine Stop/Start (ESS) system on my 2018 Chrysler Pacifica Touring L. For the past few weeks, the ESS light has been on, and the engine simply won't shut off at stop lights anymore. It used to work perfectly fine.

I thought it might be the main battery, so I replaced it about a month ago, but that didn't resolve the problem. I've also checked the relevant fuses, and they all seem to be good. No other warning lights are on, and the car drives normally otherwise.

Is this a common issue with the Pacifica? Are there any known TSBs or recalls related to the ESS system for the 2018 model year? I'm trying to figure out if it's something I can troubleshoot myself or if I need to take it into the dealership. Any advice on what to check next would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

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

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ClearTheCode admin answer:

It's quite common for owners of Chrysler Pacifica models, including your 2018 Touring L, to experience issues with the Engine Stop/Start (ESS) system. This system is complex and relies on several components working in harmony. Here's a breakdown of common causes and what to do:

  1. Check the Auxiliary Battery: The most frequent culprit for ESS malfunction is a failing auxiliary battery. Your Pacifica has two batteries: the main starting battery and a smaller auxiliary battery specifically for the ESS system. Even if you replaced the main battery, the auxiliary one might be weak or dead. It's typically located in the front passenger footwell area, under the carpet.

  2. Scan for Diagnostic Trouble Codes (DTCs): Even without a Check Engine Light, specific ESS-related codes might be stored. A professional scan tool can read these. Common codes related to battery issues or ESS system faults might include P0562 (System Voltage Low) if the auxiliary battery is failing, or manufacturer-specific codes related to the ESS module or sensors.

  3. Inspect Related Sensors: The ESS system relies on various sensors to determine if conditions are safe for an engine stop. These include the hood latch sensor (if the hood is open, ESS won't engage), brake pedal position sensor, transmission temperature, engine temperature, and even HVAC demand. A faulty sensor can prevent the system from activating.

  4. Software Updates/TSBs: Chrysler has released Technical Service Bulletins (TSBs) for certain Pacifica model years addressing ESS performance and battery management. It's worth checking with a dealership if there are any outstanding software updates for your vehicle's powertrain control module (PCM) or body control module (BCM) that could resolve the issue.

When to See a Shop: If replacing the auxiliary battery doesn't resolve the problem, or if you're unable to scan for codes, it's best to take your Pacifica to a Chrysler dealership or a reputable independent shop specializing in modern vehicle electronics. Diagnosing ESS issues can be tricky due to the integrated nature of the system, and specialized tools may be required to pinpoint the exact cause.

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