I recognize some of you might consider this a blessing.

Anyway, I was driving around all morning today and not once did the auto stop/start kick in. Lots of traffic light stops and four errand stops shutting off the engine.

I've never had that happen before. I checked the obvious stuff like tow/haul and sport modes being off, applying full brake pedal pressure, etc. Temp was in the 50's so I wasn't using climate control.

The one oddish thing was that once I noticed and started paying close attention, when I would come to a stop, it sounded like the engine started revving down, then revved right back up. The best explanation is that it started to do the auto stop, then said "nah" and idled back up. It really sounded and felt like it does just as it goes into auto stop, but just doesn't quite make it.

Anyone else had it not auto stopping for long periods? I'll continue to monitor it over the next few days. The not auto stopping wouldn't bother me at all, other than maybe it's an indicator of something else wrong that should be diagnosed at the dealer. 2016 2.7L with 3500 miles on it.

Thanks for any input!

 

Would this happen if the battery was not fully charged?

 

So I have to first apologize for posting the topic before a thorough search of the forum, as there were some past similar topics.

A low battery charge seems to be one possibility, but I couldn't find any numbers for "low". The truck did in fact happen to sit for nearly a week before I drove it today, but I can't imagine the battery draining that much. Also, I drive 10 miles of country road at 55mph in, then back from town, so you would think that would have gotten the battery back up after sitting for the short time. Who knows though.

The icon was greyed out the whole time, but I can't remember if it's supposed to be green all the time, or just when auto stop has happened. I checked on the readout, and it gave the "engine operating normally" message. My understanding is that if there is a problem, it will say why auto stop is not active (low battery, for instance). But maybe that's just on higher end models? I have the XLT with the 501A package.

 

If you have a voltmeter...a quick test for voltage will help reveal if you have a low battery. Keep in mind...if the battery is low...it could be a defective battery.

Here is a matrix for battery charge...

Battery Voltage and State of Charge:

12.66v . . . . . . . . . . 100%
12.45v . . . . . . . . . . 75%
12.24v . . . . . . . . . . 50%
12.06v . . . . . . . . . . 25%
11.89v . . . . . . . . . . 0%

If at or below 50%, then battery should be recharged with a quality charger. Do NOT use your alternator to charge up your low battery.


biz

 

Why is that?

 

Thanks, I'll check it this morning as I'm curious. On the numbers, I was wondering what the threshold voltage was for auto stop to run (or not).

 

Engine temperatures were up? Mine won't auto stop until the temps have come up on my 2016 lariat.

 

So it has become more interesting.

Unfortunately I was not able to check battery voltages before I drove it this morning as I got a call that had me hightailing in to town. However, everything started working as normal again on the way in. Also on the way back until...

On one of the last stoplights, the icon greyed out again and it wouldn't autostop. Then my last stop sign, it auto-stopped. Then when I got home, I drive down a 1/4 mile private road, so I stopped a few times on the way to the house. Three out of four times it auto-stopped, but the second of the four, it didn't.

I also had the message screen on. It kept showing "normal operation" when it didn't autostop and the icon was greyed out. Just to doublecheck, I did stuff like turn the steering wheel and unbuckle my seatbelt. When I did those things, I got the "autostop off because..." message. But no message when it was doing its random thing.

So my first thought this morning was that maybe it was in fact the battery voltage, but now I'm wondering if it's something else. I'm almost thinking the brake pedal might be a suspect. I think I noticed that it felt mushy when I was pressing down when autostop was not working, but not so when it was. Maybe just my imagination, but I'll continue to experiment.

On the autostop icon itself: Yesterday it was visible and greyed out the entire time I was driving (and again, message center was showing "normal engine operation"). Today, it was only visible and green when it was active (brake pressure applied and vehicle stopped), then disappeared when the engine started again. Two of the times autostop didn't work, it just came on greyed out when I was stopped, then turned off. One time it came on and stayed on greyed out while I was driving up until my next stop.

Anyway, weird. I guess I'll just keep monitoring to see exactly what's going on. For all I know, it's working as it should and the not turning on is normal operation. Though it seems like it should be giving me a message for why, similar to when I unbuckle my seatbelt.

 

. Because a low battery or a defective battery will keep the alternator charging to the point of damage, an alternator or a starter have duty cycles, the higher the duty cycle, the higher the quality level of the components, factory OEM starters and alternators are generally of a higher quality, but a battery that is not functioning properly will keep an alternator working too hard. It sounds like the battery was sufficiently discharged to the point that it needs to be charged with a battery charger, I don't think this will set a check engine light off. In our fleet of heavy trucks, all of the new volvo's and Freightliners have battery disconnect switches on them and are turned off for the week end, these trucks have three and four group 31 900 cca battery's. The amp draw on one of these trucks sitting for an extended length of time,(like two or three weeks) will kill the battery's flat, many garage queen cars need to have a battery tender hooked up to them as they don't go out often enough to keep the battery up.

 

Auto start stop will not always work, especially when you are in tow/haul mode or are using climate control on max and it thinks the temp will deviate more than 4 degrees in either direction (heat/ac) took a snapshot of esourcebook for you.

 

Thanks. I had also found this General Service Bulletin:

http://m.ford.oemdtc.com/GSB/G0000115.pdf

I understand it won't always stop/start. My main concern was that yesterday it didn't do so once in an entire morning of driving. I'd never seen it do that before.

 

In training they told us that it will only work if everything checks out perfect. There is a module in there that checks quite a few parameters to give a green light or a no go with the system.

 

Ah, interesting. So there could be situations where it doesn't activate, but also doesn't say why in the message center? I think that's part of my confusion, since it will display messages for many of the parameters that deactivate it, but was not showing any yesterday at all and sometimes not today.

 

There are so many messages it will give you, I assume the truck was concerned with keeping the climate control at the desired temp. That is one of the most common reasons for it not activating.

 

Just as an update, it looks like it must have been the battery voltage. Driving every day this week, the auto stop/start is back to functioning "normally", or at least the way I'm use to it functioning.

I'm surprised that only five days of sitting would bring it to the point that auto stop wouldn't engage. It must have a pretty conservative threshhold voltage, which probably is a good thing.

At some point for kicks, I'm going to try to let the truck sit again for 5-6 days, check the voltage, then drive it and see if it does the same thing as in my OP again. Then check the voltage again.

I still haven't found any documentation on actual voltage numbers that would be the threshold for auto stop to not engage, so maybe it's a sliding scale depending on other system factors the computer takes into account.