Auto Start Stop Question / Confirmation

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Dec 9, 2019 | 08:21 PM

Jonesy0027

Thread Starter

Tuned

Joined: Feb 2012

Posts: 378

Likes: 16

Auto Start Stop Question / Confirmation

Howdy Fellas,
Today I realized my trucks auto start stop function only shuts off the engine at a complete stop when my heater blower is set to ‘vent’.

When the heater blower is set to ‘defrost’, the engine will NOT shut off at a complete stop.

I don’t think it’s a problem, just how the system functions.

Please let me know if you’re truck functions the same. Appreciate your input.

Dec 9, 2019 | 08:26 PM

scott91370

Fleet Mechanic

Joined: Dec 2008

Posts: 1,914

Likes: 136

From: Burleson, Tx

More than likely since the a/c runs in the defrost position it keeps the engine running. But I bet the section on Auto Start/Stop in the owners manual will tell you for ure.

Dec 9, 2019 | 09:44 PM

smokewagun

Cargo Master

Joined: Feb 2004

Posts: 2,101

Likes: 60

From: N. Illinois

I doubt the “A/C” function is the switch keeping the truck running, but I’d bet dollars to donuts the “defrost” being a safety issue (you can’t see out frosty windows or if the windshield is icing) that keeps it running. I have the *** permanently disabled, so I can’t confirm defrost, but *** will operate with the A/C on and heat, depending on other variables.

Dec 9, 2019 | 10:42 PM

TJReams

Fleet Mechanic

Joined: Sep 2016

Posts: 1,801

Likes: 48

From: Abilene TX.

It won't let the engine shut off on max defrost or max ac. It will not shut off the engine, if the engine temp is not satisfied, interior temp is not satisfied, or if the trans is in neutral or manual shift mode. Not counting Trailer tow or Sport mode. It is in the manual.

Dec 9, 2019 | 10:52 PM

ford390gashog

Fleet Owner

Joined: Jan 2004

Posts: 26,007

Likes: 575

From: Brentwood,CA

The gauge display will tell you the reason the engine stayed on for that cycle. The cluster will display " Engine On - Low Temperature ", " Outside Temperature ", " Charging " and so forth.

Dec 11, 2019 | 01:22 AM

ArthurLaurent

New User

Joined: Dec 2019

Posts: 4

Likes: 0

My Auto Start-Stop function had stopped (2018 F150 Lariat 3.0-L PowerStroke Diesel 4WD with most of the bells & whistles and 18K miles.). Not that I even noticed; I thought the truck just hadn't (ever) warmed up. Last night, I got a message on my dash that the Start-Stop was disabled because of inverter use. I had plugged in a Motorola charger for my HT way back at the end of June; even though there was no battery charging in it, the charger was still "on" enough to draw current from the inverter. Just in case you want another way to bypass you Auto Start-Stop... Arthur

Dec 11, 2019 | 08:20 PM

lwk362393

Tuned

Joined: Jun 2013

Posts: 344

Likes: 5

From: North Shore MA

It's funny, after reading this thread I paid a bit more attention while driving my truck tonight and noticed that it DID shut off at a stop light even when I had the defroster on. I only had it set to defrost (but not the max defrost setting), no vent, and sure enough the auto stop/start activated. I was a bit surprised actually because it's cold here in MA tonight, mid 20s, and the truck wasn't up to operating temperature yet. The heat kept blowing while it was off, as far as I could tell. I'm guessing it only won't shut off when MAX defrost or A/C is on, presumably because it has to run the blower/compressor a lot harder. Just my $0.02.