Silves

I have a 2015 F150, 2.7l with auto stop feature. The truck has just over 12,000 miles and recently the auto stop system has failed to work consistently. The manual lists a number of reasons the auto stop system will not be enabled but none of them apply. When the system fails to stop the engine the cause is always listed as vehicle charging, despite the fact that the truck has been driven15 to 20 miles with no AC or heating on or other apparent battery drain which would cause the system to be charging. The dealer has checked the battery and charging system and claims everything is fine with the charging system and the auto stop feature should be enabled and stop the engine. They admitted they do not know what to do and have requested help from the corporate experts.
I still am waiting for their response.
Has anyone else encountered this?
Richard

dantrigg

I had the same exact problem and the dealer replaced the battery under warranty. Problem solved.

Napalm

If you have a 3 year old vehicle with only 12000 miles on the clock your battery is most likely flat. or starting to die rather. unless you leave it on a trickle charger while parked religiously.

Even then it's probably still dying. Here's the thing - if the dealer tech bothered to look it up with the scan tool you can ask the car what it says the battery condition shows. If I recall correctly this is shown a a % charge depth. Think in terms of life expectancy.

Anywho % less than 40 - and Auto start will disable.

Napalm

I hate when I do this - I went too fast.

So the why - the battery condition monitor system is always testing the battery condition - when it gets weak enough the start stop will disable until the condition comes up (like with a longer drive or highway trip) or a reset with a new battery.

As such - batteries in the new car when you get it are often weaken and today you're doing good to get 3 years out of a battery.

Rainman4Tech

What Napalm said my 2015 XLT CrewCab with 40+K on the clock would do the same, not be constituent with start/stop unless I had driven it 30 minutes or more to build the battery back up. Always gave battery charging as the reason start/stop not available and replaced battery and all was shiny.

Raymond

elptxjc

I think the main problem is the 'smart battery charging' or something like that. The system assumes an older battery can't take the drain anymore, and triggers that. I don't think charging your battery every week (like I do) changes that, since the 'smart' part is an algorithm, just like the 'oil life monitor', rather than stress-testing the battery, or checking oil condition. I remember seeing a way to activate or deactivate that while messing with the menus, but maybe it was something else. At any rate, batteries are relatively cheap, so changing it every 4 years or so seems like a good preventive maintenance. I always deactivate start/stop, so that won't be an issue to me. He he. The good news is sport mode automatically deactivates it, so don't have to hit the button every time I start the car... but I still have to change to sport mode. At least it's one or the other, and not both. He he. Good day folks.

Napalm

Your new car and this dates back to around 2007 for many - has a system that monitors the battery condition via internal resistance and current capacity and voltage brought in. In other words the car has on board at all times a battery tester. This condition is kept by the computer so as to keep an eye on the state of the battery. IN FACT when you have the vehicle shut down for more than 5 hours it does a periodic sample test of the battery at rest to check it's internal resistance and it's voltage depreciation over time. If the can never goes to sleep - this doesn't happen but that's a longer winded post.

But yes your newer car knows the state of the battery quite well. Few other things on a short drive your battery might not charge back completely from the initial cold start. WHy your alternator doesn't put out a constant power - instead it varies it's amp and volt output based on the electrical load state and the state of charge of the battery - thus reducing the mechanical drag on the belts and of course reducing the amount of robbed engine power. It will - to reduce power needs - on short trips let the battery gradually fall down because it can be topped back up. If however you do a single short trip a day you might not get back to 100%, which means in a week or 2 you might not be at 90% - and rinse and repeat enough you might have a battery that only has 50% of charge depth (capacity) in it. Put that battery on a charger for a while or take a 2 hour road trip and that capacity would go back to 80% or so. But if you don't do that - it's sitting at 50%.

Why does that matter - The start stop logic is setup with some margin so you aren't left sitting at a light and the engine won't start - so the buffer is in my opinion high. If the battery condition isn't above a set value then start stop and disabled. If I recall correctly that value is 40% of the charge capacity. Another measure of this that might be more tangible for you is if the resting battery voltage is below 10.5Vdc.

Hope this helps explain things - and yes your new car monitors more going on that most people realize. FYI if you haven't read the whole manual you should also know it has a data event recorder as well.

breakers28

tenx82, I cannot confirm exactly what kingofwylietx recommended as I'm not familiar with the devices he mentions. However, I do believe they are similar to the use of a TR-7 and a relay as follows:


TR-7 and Relay wired to Auto Start Stop


I used the following setup in my truck for a while. Since I never used ***, I finally used Forscan to permanently disable it, and replaced the Hazard/*** switch with just a Hazard switch it doesn't look like my truck ever had *** (the new switch is about $12 and does not have the *** button).... Anyway, many ways to do this, hope this gives you some idea. And if you want a more detailed explanation on how this works, send me a PM and we can talk on the phone.

NOTES:
- The TR-7 instructions will indicate the green wire should be connected to constant 12V but in this setup, that is not necessary. It can be connected to switched 12V.
- A TR-7 is a device which has been around for years. It was originally designed to allow aftermarket car stereo players to be used with video (as an override which would allow one to watch a video on the car stereo when the car was in motion). It has a few other functions in it as well, the one that is important here is Feature #9 which was designed to lock/unlock doors in a car after the ignition was turned on/off. Feature #9 simply outputs a Negative battery pulse in order to lock or unlock a car door (when wired correctly). Upon ignition on, the TR-7 waits 3 seconds and outputs a negative pulse - this can be used to momentarily simulate the user pushing the *** (Auto Start Stop) button. In my example it is used in conjunction with a relay.
- TR-7 can be purchased on Ebay or Amazon for about $15
- A relay can be purchased from Ebay, Amazon, O'Reilly, Autozone, etc for less than $10
- One of the challenges in this set up is connecting to the existing wiring harness. The wires in the *** switch are very small (I'd guess 24 or 26 gauge). This solution would require tapping into the Purple/Black and the White wire on the *** switch.
- Once you receive the TR-7, it must be programmed to operate for Feature #9. It comes with instructions, and takes about 5 minutes to gather the leads and program.
- The blue, orange, and brown wires on the TR-7 are not used

southern_f150

RL1990

As usual Ford is just ahead of the game. The new Ram has it and so will the new GM twins.