TODDIO63

I'm new to the forum and can't find a thread with my topic. I have a 2015 2.7 ecoboost. Around 11,000 miles my start/stop feature quit working. Then I would occasionally get a message stating a parking break malfunction and then it would hesitate after pulling onto a street when accelerating. After that it started to crank slow after sitting a few hours. I took it to the dealer when it wouldn't turn over until the third attempt to start it. Turned out to be a bad battery. Battery replaced at about 12,400 miles. At 12,700 Start/stop not working I took it to the dealer for a different repair and mentioned the start/stop still not working and the dealer said give it some time. 3 days later the Start/stop activated once after 7 days of the new battery. I turned off everthing I could to limit the electrical draw and it still won't shut off while stopped. Now at 13,100 miles the parking brake malfunction came on and later disappeared. Dejavu setting in. Prior to 11k start/stop worked perfectly and with AC or heat on, headlights on and stereo on, etc. Now I have lost 1-2 mpg. Anyone out there know how to guide the dealer as I get the "certain conditions have to be met for start/stop to work" line i.e. Battery voltage had to be above a certain point. Is the alternator having issues or does something need to be reprogrammed. Thanks for any direction or advice.

gatorblue92

It does sound like it could be a weak alternator. Having a 2nd bad battery is possible but not very likely.

tmcolegr

Good information on Stop/Start

BadAV

Sorry you are having problems but if I had start/stop (I don't - I have the 3.5 Eco) I would be happy if it quit working. They maybe beef up the starter to handle it, but it's got to be extremely hard on the starter, alternator, and other parts of the electrical system to continually cycle on and off like that. It's one of the main reasons I bought the 3.5 Eco instead of the 2.7.

Ricktwuhk

You are not well informed on this subject. My Fusion Hybrid has been starting and stopping just fine for 7 years now. Components are designed for it.

BadAV

Come back in another 7 years with at least 200k miles and then I will say Ford did OK with their design. Until then my Engineering and Quality background says otherwise.

Xlt5

Clearly you've analyzed all of ford's engineering specs and design with respect to the auto start/stop before coming to your conclusion, yes?

Can't imagine someone with a background such as yours would make such a statement without knowing all of the facts...

BadAV

7 years is not a long time. I kept my last truck 14 years and have kept several others as long. Time is the enemy of reliability. As to Ford Engineering, I have seen plenty of specifications on their prints that were copied from previous prints. Those specs had no relevance; the engineer copied them because the old and new product looked alike. The manufacturing process was completely different so there was no way to meet the specification. New engineers who didn't know what they were doing. Lest you say it was uncommon, some of the specs had been copied for 3 generations of product. Those sre the real facts of 20 years of tier 1 OEM automotive supply.

BoozeDaily

iTrader: (2)

OP is there any particular weather issues (heat) that might be affecting the Start/Stop functionality?

This entire summer my Auto stop/start wasn't working due to the heat. A few times it got down to low 70s in the morning and it would work but for the most part my dash had an A with the line through it.

I read that you limited the electrical load to the system but is there an ambient temp monitor that makes it not functional past a certain temp?

TODDIO63

My mind is blown. A couple of evenings this past week the auto start/stop engaged. Scenario AC off, windows down, headlights on, temps in the low to mid 70s, and vehicle only running a few minutes in city driving. The past two mornings AC off, windows down, headlights OFF, temps in the upper 60s running 35 minutes 15 minutes stop and go an 15 minutes open highway and start/stop not activate. Have 13k+ now first 11k it activated nearly every time I stopped even during August heat with AC on. I wonder if some sensor is malfunctioning.