The auto start/stop system in Jeep Grand Cherokee is designed to help save fuel by turning the engine off when you come to a stop. If you see error message Start/Stop Unavailable Service Start/Stop System in the instrument cluster of your Grand Cherokee, it means the start/stop system has detected a malfunction and is disabled.
The most common cause of start/stop unavailable error message in Jeep Grand Cherokee is dead auxiliary battery.
Replace the auxiliary battery
In majority of the cases, replacing the auxiliary battery in Grand Cherokee fixes the Start/Stop unavailable error and restores the system. The auxiliary battery is located under the front passenger seat just next to the main 12 volt battery. The part number for the auxiliary battery is AUX14, and costs about a hundred bucks.
- Slide your passenger seat forward, which will reveal a plastic panel in the floor.
- Lift up the plastic panel.
- Disconnect the negative side of the auxiliary battery first using a 13mm socket wrench.
- Disconnect the negative side of the main 12 volt battery using a 10mm socket wrench.
- Disconnect the positive side of the auxiliary battery using a 13mm socket wrench.
- Disconnect the vent hose from the top of the auxiliary battery. It is connected at two points, remove both of them.
- Remove the retaining nuts from the strap that is holding the auxiliary battery.
- Lift and remove the retaining strap from the auxiliary battery.
- Remove the battery.
- Reinstall the new battery in reverse order: Retaining strap and its nuts > vent hose > positive connecter AUX battery > negative connector main battery > negative terminal AUX battery.
Followed this procedure and went from Aux Battery charging message to Start/Stop Malfunction and needs service. Will this clear its self or have I wasted $100 replacing the battery and have to go to the dealer?
The new battery may not be fully charged. Driving for 20-30 min should charge the battery.
Thanks for the reply Will. I have driven for a few trips some as long as 1hr or engine run time. I assumed the Aux voltage would need to become one with the main battery. I have also ordered a battery conditioner and will give that a whirl “if” routine driving does not address the issue.
Had the same error message, Autozone was out of batteries, found one at Oreillys, changed out the pins and replaced the Aux battery following the video’s instructions, Error code disappeared immediately. Thank you very much!! A+++++
Thank you for sharing this. Fixed the same problem. O’Reilly had the battery! Just needed a 10mm deep socket from Lowes
I had same error for start stop not working, replaced auxiliary with new one but got same message the next day. Any other causes likely? 2016 Jeep Grand 3.6
Same error on new 2022 one. Took to dealership, replaced the battery and still won’t work. Sat for 2 hours at a scheduled appt at dealership at main shop and never even touched it. So would love a solution if you ever find one
Having the same issue on a 2019 JGC. Getting that same message about the stop start unavailable. The vehicle starts but the motor is sputtering, is this normal? If I replace the aux battery, why would that stop the motor spuddering? I will start by replacing the aux battery I guess. Very good instructions from you btw. Please help. Oh, had no issues driving to work, just happened after my shift out of nowhere. Mild temperatures here too. Thank you-John
Also, the motor light is on too……along with that “A” symbol.