John Welsh (Moderate Supporter)
John Welsh (Moderate Supporter) Mod Squad
11/16/20 8:36 a.m.

2010 Ford Escape 3.0L awd w/ 107k

I have here a friend of the family's car.  Her battery light is on.  The car has never left her stranded or not started.  No check engine light is coming on.  No codes on my reader.  

Battery is 2 years old and correct unit.  Volts while running and not running seem correct.  The battery load tests well too. 



12v when not running

14v when running


Terminals are clean.  Battery from 6/18

Immediate ground looks clean



John Welsh (Moderate Supporter)
John Welsh (Moderate Supporter) Mod Squad
11/16/20 8:47 a.m.

The battery light does not come on immediately when starting the car but does come on shortly after starting.  Seems to come on about the time you shift the car into reverse.  That is not to say that reverse initiates the light but rather an example of how long it takes for the light to illuminate.  When starting the car an just leaving the car idling for a prolonged period, the light will still come on in less than 30 seconds.  

John Welsh (Moderate Supporter)
John Welsh (Moderate Supporter) Mod Squad
11/16/20 9:11 a.m.

This is the rust belt so I did pull every connection (terminals and chassis ground) and hit them with some sandpaper to "rough up/improve" the connection.  No success.  The battery light still illuminates the same.  

BlueInGreen - Jon (Forum Supporter)
BlueInGreen - Jon (Forum Supporter) UltraDork
11/16/20 9:17 a.m.

This may just be a random anecdote and not anything helpful; but the battery light in our Focus has been on like that for years. I haven’t bothered investigating further since it charges, always starts, and the original battery lasted a normal life span.

Saron81 HalfDork
11/16/20 9:50 a.m.

Check fuse 6 (15a) in the under hood fuse box. 
Otherwise, it's a PCM controlled alternator. May actually need a PCM or an instrument cluster. 
Fords diag starts at the cluster with no PCM DTCs.

John Welsh (Moderate Supporter)
John Welsh (Moderate Supporter) Mod Squad
11/16/20 10:31 a.m.

Thanks for the lead but, sad to say, fuse #6 looks good. 


I even went so far as to swap two 15a fuses incase one fuse was bad but somehow looked good.  No change.  Both 15a fuses are the same which I think is good.  

Streetwiseguy MegaDork
11/16/20 11:32 a.m.

Well, if it makes you feel any better, 9o% of the post 2000 cars I see with a dead alternator don't have the warning light on, and 90% of the cars with the light on are charging just fine.

You are sure there are no codes?  There is a base charging rate controlled from the regulator, then a communication line from the ecu that ups it when required.  I've seen non-Ford regulators cause it, broken wires at the small plug on the alternator, even a bad wire in the drivers door once, but there is always a code of some sort.

glueguy (Forum Supporter)
glueguy (Forum Supporter) Dork
11/16/20 11:33 a.m.

Scanner with data streaming? I'd be curious to watch what the computer thinks is happening when the light turns on. Can you see a voltage drop/spike?

John Welsh (Moderate Supporter)
John Welsh (Moderate Supporter) Mod Squad
11/16/20 11:43 a.m.

Bad voltage regulator has been on my mind but I'm not seeing evidence.  I hooked up my bluetooth ELM an ran Torque app while driving.  While running I'm seeing 13.9 to 14.5 (lots of 14.1)   Is 14.5 too high?  

Screenshot of my Torque app.  So many blank values because this screen is set up for reading Prius batteries, etc.  What it is showing is 14.3 read at the control module and 14.4 read at the obd2 adapter.  


John Welsh (Moderate Supporter)
John Welsh (Moderate Supporter) Mod Squad
11/16/20 12:01 p.m.

With Torque app I ran volts as a graph. I took this screen shot right as the dash light for battery came on (which is about 30 seconds after starting the car. 

Steady state. 

Streetwiseguy MegaDork
11/16/20 1:20 p.m.

Ignore the voltage.  That isn't the problem.  The alternator is charging, but the control circuit to the ecu is not giving (or getting) the response it wants to see.


Is your scan tool able to read "gen mon" or "gen ---something"?

5/25/22 9:41 a.m.

Did you ever figure it out?

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