Service charging system now
Thread Starter
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Cross-Country
Joined: Jan 2006
Posts: 95
Likes: 4
Service charging system now
2015 f150 3.5 eb 95K mi. The "service charging system now" warning flashes after starting the truck and the battery light in the dash stays on all the time.No other trouble codes and check engine light is not on.
I got a pinout for the alternator wiring to the pcm and to fuse#38 (fuse not blown) I checked continuity on the 2 wires going to the pcm and they are good from the alternator to the pcm connector. The wire that goes to fuse #38 has 12v at the plug that goes into the alternator.
Alternator is charging and voltage at the battery while running is around 15.3V @2000 rpm. What voltage should I see on the 2 wires going into the pcm if I back probe them ?
I got a pinout for the alternator wiring to the pcm and to fuse#38 (fuse not blown) I checked continuity on the 2 wires going to the pcm and they are good from the alternator to the pcm connector. The wire that goes to fuse #38 has 12v at the plug that goes into the alternator.
Alternator is charging and voltage at the battery while running is around 15.3V @2000 rpm. What voltage should I see on the 2 wires going into the pcm if I back probe them ?
Moderator
Joined: May 2005
Posts: 8,227
Likes: 1,245
From: San Antonio, TX
Sounds like you have a battery issue. Alternator is working too hard to keep up. Are there any other weird electrical issues? Like gauge needles bobbing, a slower crank, or warning lights not going out right away after starting. Those are also signs of a bad battery. If that's the original battery it's definitely time for a new one. And if you replaced it and it's more than 4 years old, the same.
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
A fault lights the warnings you are getting.
There is a code associated with it if Scanned.
There is a rare time this voltage goes that high.
That is when the Battery control system (BMS) detects a special condition that requires a corrective Charge attempt at that high a level for a short time..
Otherwise the >>>AGM Battery<<< cannot be force charged at that level for to long without overheating the Cells and causing permeant damage.
Normally the Battery is never charged at a level greater the 14.8, the max safe level after a long time interval.
.
To give you more info, when cranking , the voltage will drops into the 10 volt range under Starter / Engine loading in a good fault free system, then rise to about 13.9-14 v then rise again to a higher level to re-charge the Battery but at no more than 14.8. This standard operation.
On a 2015, you have a different Sensor than 2018 and later. It is located on the Ground cable and called a Hall Sensor.
You have a fault that need addressing or there would be no indications, you get.
If you do not have an AGM, then the voltage levels will be different for a wet Lead Acid type Battery.
Good luck.
There is a code associated with it if Scanned.
There is a rare time this voltage goes that high.
That is when the Battery control system (BMS) detects a special condition that requires a corrective Charge attempt at that high a level for a short time..
Otherwise the >>>AGM Battery<<< cannot be force charged at that level for to long without overheating the Cells and causing permeant damage.
Normally the Battery is never charged at a level greater the 14.8, the max safe level after a long time interval.
.
To give you more info, when cranking , the voltage will drops into the 10 volt range under Starter / Engine loading in a good fault free system, then rise to about 13.9-14 v then rise again to a higher level to re-charge the Battery but at no more than 14.8. This standard operation.
On a 2015, you have a different Sensor than 2018 and later. It is located on the Ground cable and called a Hall Sensor.
You have a fault that need addressing or there would be no indications, you get.
If you do not have an AGM, then the voltage levels will be different for a wet Lead Acid type Battery.
Good luck.
Thread Starter
|
Cross-Country
Joined: Jan 2006
Posts: 95
Likes: 4
The battery is not the problem. It tests fine with a load tester which is more sensitive than the trucks ability to detect a bad battery.
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Thread Starter
|
Cross-Country
Joined: Jan 2006
Posts: 95
Likes: 4
A fault lights the warnings you are getting.
There is a code associated with it if Scanned.
There is a rare time this voltage goes that high.
That is when the Battery control system (BMS) detects a special condition that requires a corrective Charge attempt at that high a level for a short time..
Otherwise the >>>AGM Battery<<< cannot be force charged at that level for to long without overheating the Cells and causing permeant damage.
Normally the Battery is never charged at a level greater the 14.8, the max safe level after a long time interval.
.
To give you more info, when cranking , the voltage will drops into the 10 volt range under Starter / Engine loading in a good fault free system, then rise to about 13.9-14 v then rise again to a higher level to re-charge the Battery but at no more than 14.8. This standard operation.
On a 2015, you have a different Sensor than 2018 and later. It is located on the Ground cable and called a Hall Sensor.
You have a fault that need addressing or there would be no indications, you get.
If you do not have an AGM, then the voltage levels will be different for a wet Lead Acid type Battery.
Good luck.
There is a code associated with it if Scanned.
There is a rare time this voltage goes that high.
That is when the Battery control system (BMS) detects a special condition that requires a corrective Charge attempt at that high a level for a short time..
Otherwise the >>>AGM Battery<<< cannot be force charged at that level for to long without overheating the Cells and causing permeant damage.
Normally the Battery is never charged at a level greater the 14.8, the max safe level after a long time interval.
.
To give you more info, when cranking , the voltage will drops into the 10 volt range under Starter / Engine loading in a good fault free system, then rise to about 13.9-14 v then rise again to a higher level to re-charge the Battery but at no more than 14.8. This standard operation.
On a 2015, you have a different Sensor than 2018 and later. It is located on the Ground cable and called a Hall Sensor.
You have a fault that need addressing or there would be no indications, you get.
If you do not have an AGM, then the voltage levels will be different for a wet Lead Acid type Battery.
Good luck.
I scanned it and there's no faults, i wish there was.
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Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
Well, you can't keep saying everything is fine and no faults found and still have an issue.
When the charge Indictor comes, on anytime, the Alternator is not outputting, even for a short time.
There is a reason why.
Alternator Brushes worn down, Alternator basic regulator, Cables, Ground connections, wire harness, Plug-up etc.
The codes are in the P0621, 625, 626 area for charging systems, even if not solid.
Look them up to see what the system is able to detect.
We cannot help any more on this basis.
Good luck.
When the charge Indictor comes, on anytime, the Alternator is not outputting, even for a short time.
There is a reason why.
Alternator Brushes worn down, Alternator basic regulator, Cables, Ground connections, wire harness, Plug-up etc.
The codes are in the P0621, 625, 626 area for charging systems, even if not solid.
Look them up to see what the system is able to detect.
We cannot help any more on this basis.
Good luck.
Thread Starter
|
Cross-Country
Joined: Jan 2006
Posts: 95
Likes: 4
Well, you can't keep saying everything is fine and no faults found and still have an issue.
When the charge Indictor comes, on anytime, the Alternator is not outputting, even for a short time.
There is a reason why.
Alternator Brushes worn down, Alternator basic regulator, Cables, Ground connections, wire harness, Plug-up etc.
The codes are in the P0621, 625, 626 area for charging systems, even if not solid.
Look them up to see what the system is able to detect.
We cannot help any more on this basis.
Good luck.
When the charge Indictor comes, on anytime, the Alternator is not outputting, even for a short time.
There is a reason why.
Alternator Brushes worn down, Alternator basic regulator, Cables, Ground connections, wire harness, Plug-up etc.
The codes are in the P0621, 625, 626 area for charging systems, even if not solid.
Look them up to see what the system is able to detect.
We cannot help any more on this basis.
Good luck.
I'm not trying to be difficult, I'm just making all the information known. I'll scan it with another scan tool and see if I get a different result. I agree something is wrong.
If I could have gotten any codes out of it I probably wouldn't be here asking for help.
......... ok so i just went out and did a battery test and alternator test through a scan tool. Battery tests good (dipped to 8.8V during start) and alternator tests good, currently charging at 13.93V battery light is still on and "service charging system" alert still activates 30 seconds after you start the engine.
Zero codes,none,nodda,zilch,zero, lol
Moderator
Joined: May 2005
Posts: 8,227
Likes: 1,245
From: San Antonio, TX
Your battery shouldn’t drop below 10 when starting it. Dropping to the 8s means it could very well not start any time now. We’ve given our advice, and I wish you luck.
Another thing you may want to check is the cables and grounds. Not just at the battery end, but at the starter, frame and the frame to body ground. Check that they are good and tight. Clean all connecting surfaces. If you see corrosion going under any insulation, replace those cables.
Another thing you may want to check is the cables and grounds. Not just at the battery end, but at the starter, frame and the frame to body ground. Check that they are good and tight. Clean all connecting surfaces. If you see corrosion going under any insulation, replace those cables.
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
Three things you see, Dash light is on and cranking voltage is to low (you should hear it as slower turnover), and Running voltage is way to low at below 13.9, should be up too max 14.8 limit on a low Battery.
.A. The Alternator has a regulator in it like old times as a base backup.
The regulator puts out a Ground to put the Dash light (on )when the engine is >not running<, before starting.
When the engine is running, the regulator takes that ground Off and puts the Dash light out as a normal indication the Alternator voltage is up to normal output.
If the Dash light is on with engine running it is a fault. The Regulator is not taking the ground off, for some reason..
B. The voltage measured running is too low, indicates the same thing, just shows in a different measurement.
Both point to a faulty Alternator.
All the voltages being low indicate the same thing..
Can't keep or Charge a Battery under these operating conditions.
Best I can do to help understand.
Good luck.
.A. The Alternator has a regulator in it like old times as a base backup.
The regulator puts out a Ground to put the Dash light (on )when the engine is >not running<, before starting.
When the engine is running, the regulator takes that ground Off and puts the Dash light out as a normal indication the Alternator voltage is up to normal output.
If the Dash light is on with engine running it is a fault. The Regulator is not taking the ground off, for some reason..
B. The voltage measured running is too low, indicates the same thing, just shows in a different measurement.
Both point to a faulty Alternator.
All the voltages being low indicate the same thing..
Can't keep or Charge a Battery under these operating conditions.
Best I can do to help understand.
Good luck.
Thread Starter
|
Cross-Country
Joined: Jan 2006
Posts: 95
Likes: 4
I replaced the battery and the alternator and just as I suspected neither of those were the problem. I did finally get 2 codes out if it though, P0625 and P065B. I've suspected the PCM all along and as mentioned in my first post I'm trying to find information on how to test the inputs/outputs of the pcm in relation to the alternator, whether that be with a scope or a volt meter or whatever it takes. Seems very difficult to get service information on this subject. I guess people just blindly start replacing everything and hope for the best ??? That's not the way I like to do things, replacing this alternator was a good example of why.