Check Charging System Light

09brian0 said:

Just adding the simple stuff, check for loose/worn belt?

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Gotta point there. Check the tensioner as well. If it's slipping that'll be a contributor. May be worth having a friend sit in the car and rev it up to ~2K and see what the output is across the battery. Still think there's a ground issue. (I know, my opinion only).

I had the same light come on as well. Changed the alternator, no change.
Come to find out, the smaller bolt on the battery connection was loose.
Easily overlooked when you grab the connection at the post and check it for looseness. It was solid, but next to it is a smaller bolt, that I used to hook up my battery tender came loose, and theres a wire attached that I believe goes to the alternator. Tightened it up, all was good.

Stoenr said:

I had the same light come on as well. Changed the alternator, no change.
Come to find out, the smaller bolt on the battery connection was loose.
Easily overlooked when you grab the connection at the post and check it for looseness. It was solid, but next to it is a smaller bolt, that I used to hook up my battery tender came loose, and theres a wire attached that I believe goes to the alternator. Tightened it up, all was good.

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Jesus, go thru all of this for a loose connection? Wouldn't that be a hoot!

Turns out it is overcharging?! Was supposed to be a drop-in replacement that needed no additional upgrades. Hope I didn't fry my PCM. Unfortunately, it seems a new OEM alternator is the quickest solution. 2 year warranty, so we'll see...
What a PITA.

I had "check charging system" diagnostic error for years on my 05 Sallen. A good friend who had recently retired from Ford engine in Cleveland is a walking encyclopedia of knowledge. I told him what has been going on and he asked if I had figured it out yet?. Obviously I hadn't. He told me t in 10 Ford changed suppliers and that brand of alternators solve Fords charging issue. Denso is the brand name. Since installing it 3 years ago I have had no problems . I run wide band AreoForce gauges and they show that the voltage has never been below 13.7 volts.

Read through the thread, try this one on for size. Bought an 06 GT a couple months back. Got the CCS light for 5 seconds about every 3 weeks. Decided to be proactive and replace the alternator. Had the battery tested also. Battery was testing better than new. Alternator was showing 13.7 ish. Fine, bota boom, new alternator installed.
this morning the CCS light comes on after 30 seconds and wont go away! Retuned to AA and had the new one AND the old one retested. Both passed. Hmmm
Alternator ahowing 14+ and battery 12.9 at idle. Is it the battery?
More importantly, can I drive it with the light ON since everything ‘passed’? What could I further damage?
Thanks in advance,
Joe in Denver

should have mentioned, car has 58k miles and is bone stock. Nothing aftermarket. When the CCS came on before, it was random….in the driveway, on the interstate…at a drive thru, no constant to it.

Fava-beans said:

Read through the thread, try this one on for size. Bought an 06 GT a couple months back. Got the CCS light for 5 seconds about every 3 weeks. Decided to be proactive and replace the alternator. Had the battery tested also. Battery was testing better than new. Alternator was showing 13.7 ish. Fine, bota boom, new alternator installed.
this morning the CCS light comes on after 30 seconds and wont go away! Retuned to AA and had the new one AND the old one retested. Both passed. Hmmm
Alternator ahowing 14+ and battery 12.9 at idle. Is it the battery?
More importantly, can I drive it with the light ON since everything ‘passed’? What could I further damage?
Thanks in advance,
Joe in Denver

should have mentioned, car has 58k miles and is bone stock. Nothing aftermarket. When the CCS came on before, it was random….in the driveway, on the interstate…at a drive thru, no constant to it.

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Check and clean all the battery and alternator connections. Especially the grounds. I don’t think you can damage anything, but you may get stranded by a dead battery if you take it out.

I was considering putting together a ‘roadside alternator kit’. Now I’m thinking about putting the old one back in. See if the light goes away again or…..?

Fava-beans said:

Read through the thread, try this one on for size. Bought an 06 GT a couple months back. Got the CCS light for 5 seconds about every 3 weeks. Decided to be proactive and replace the alternator. Had the battery tested also. Battery was testing better than new. Alternator was showing 13.7 ish. Fine, bota boom, new alternator installed.
this morning the CCS light comes on after 30 seconds and wont go away! Retuned to AA and had the new one AND the old one retested. Both passed. Hmmm
Alternator ahowing 14+ and battery 12.9 at idle. Is it the battery?
More importantly, can I drive it with the light ON since everything ‘passed’? What could I further damage?
Thanks in advance,
Joe in Denver

should have mentioned, car has 58k miles and is bone stock. Nothing aftermarket. When the CCS came on before, it was random….in the driveway, on the interstate…at a drive thru, no constant to it.

Click to expand...

Hey Joe,

If I'm reading this correctly you're seeing +14v at the output of the alternator and 12.9v at the battery terminals? If so, the alternator cable that goes back to the positive side of the battery (with the fusible link in it); the main battery cables or the grounds to the block (underside of passenger side engine mount) or back of the engine need to be checked/cleaned/or replaced.

If the battery cables have a greenish tinge (copper corrosion) to them may be time to get a new set. They're still available...around $60 - $100 last time I checked. When I replaced mine I saw an immediate 1v rise in output across the battery terminals.

To determine if the problem is grounds test for voltage drops with a multimeter; 1) from the case of the alternator to the engine block; and 2) from the case of the alternator back to the ground on the passenger strut tower. If you're showing any voltage drops (probably around 1 v) you may want to loosen/clean and retighten the alternator mounting bolts.

If that doesn't get rid of the voltage drops you may need to add a new ground from the case of the alternator to the passenger strut tower. Use 4 gauge; a couple of eyelets and crimp the cable using a punch & hammer or solder it with a torch. I did both.

That should put the alternator case and body grounds at the same potential. i.e. You should see the same voltage across the battery terminals that you see at the output of the alternator (Alt + terminal to alternator case ground).

Since I posted I spoke to a lifelong friend whose owned several Mustangs over the years. He and I decided that I should put the old one back in and see what happens. I did. Now, no CCS light. Aarrrgggg!
I put together my roadside kit anyway.
Thanks you guys, you’ve given me a honey do list.

Drove 100 miles yesterday, no CCS light. This morning, drove 90 to work. CCS light came on twice. First time for 3 miles instead of 3 seconds. When it came on the second time I ran my engine diagnostic and saw that I had 14.2 volts from the battery. I turned on the radio, parking lights and the heat….voltage dropped to 13.7ish and the light went out for the remainder of the drive. made me wonder…. does the CCS activate ONLY withlow voltage or is there an UPPER limit? One of you guys mentioned installing an additional ground. If the alternator is OVERcooking my battery does that activate the CCS light?

Fava-beans said:

Drove 100 miles yesterday, no CCS light. This morning, drove 90 to work. CCS light came on twice. First time for 3 miles instead of 3 seconds. When it came on the second time I ran my engine diagnostic and saw that I had 14.2 volts from the battery. I turned on the radio, parking lights and the heat….voltage dropped to 13.7ish and the light went out for the remainder of the drive. made me wonder…. does the CCS activate ONLY with low voltage or is there an UPPER limit? One of you guys mentioned installing an additional ground. If the alternator is OVERcooking my battery does that activate the CCS light?

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At 14.2v the alternator is Not overcooking your battery. As you put load on it however it's supposed to keep up with that load. Normal output from the alternator should be ~14.5 - 14.7vdc. However, 14.2v isn't that bad (in acceptable range). If you were seeing above 15vdc then I'd start to worry.

The reason to add an additional ground is if you're seeing voltage drops from the alternator output as compared to the battery terminals. Those voltages should be same. To test use a VOM (using VDC) from the alternator body (ground) to the passenger strut ground. If you see any voltage indicated on the meter (maybe ~.5 - 1v) you have a voltage drop and what I term a floating ground (difference in ground reference of the alternator as compared to the body ground) which affects (usually manifests as a lower voltage output from) the alternator.

In my case the fix was to replace the main battery cables (over 15 yrs old) and add a new ground from the case of the alternator to the passenger strut ground. That put the alternator ground at the same ground reference as the body ground which will maximize voltage output from the alternator. My output went from ~13v up to 14.5vdc. I've had no problems with alternator issues since making those changes.

If you want to read more about it here's a link:
Finally found the cause of my low voltage - Beware the all important grounds..

Good luck.