A few weeks ago I was driving under normal conditions, when a big red battery symbol appeared in the instrument cluster with an "OK" button. I pressed OK on the steering wheel and the big red symbol disappeared, with a small red symbol remaining in the corner of the display for a few minutes. Eventually it went away too. When I got home I noticed there was some significant corrosion on the battery terminals, so I cleaned them up and drove to a local parts store to have them check the battery. Everything was fine. It's been happening intermittently since then. I had the Ford dealership look into it when I took the truck in to have the transmission recall work performed. They couldn't find anything wrong, but it's still happening every other day or so. No issues starting or driving, and the warnings go away after a few minutes. I've checked any accessible cable ends and they're all tight. The truck has 130K miles and is still on the original alternator. The battery is 2-3 years old.
Does this issue sound familiar to anyone? Any usual suspects?

 

The light normally comes on when alternator OUTPUT falls below battery voltage OUTPUT...

Alternators have an average life of 150K miles... some more, some less............ You may have an intermittent problem with the alternator which will get worse..... this assumes your battery cables are clean and tight and ground cable is also.

I normally change out the starter and alternators at 150K miles as PREVENTATIVE maint.

 

That makes sense. Thanks!

 

Did you find the body ground and make sure those ends are clean also?

 

I have not. Will try to find some time this evening to check more wire terminations. If I don't find anything significant, I'll probably plan to replace the alternator to see if it is the culprit.

 

Wait till you price the alternator, check the grounds. Also check the hall effect sensor that serves the BMS. But I think your simple answer may be a weak battery that the BMS is rejecting.

 

Interesting. I wasn't aware of the BMS. The dealership said the battery was in good shape (down 2 cold cranking amps.) Honestly, I don't know much about what's going on in the engine compartment in this particular truck. It's been so trouble-free up until this point that I haven't spent a whole lot of time under the hood.

 

Maybe dig up the BMS reset procedure and see if that helps you out.

 

I thought the BMS dropped out some load ( radio / heater / etc) if it saw the battery was draining too fast... I don't recall the OP saying anything about equip NOT working.. Just a random LOW VOLTAGE light .

 

So the BMS is the device(?) that would cause the center (infotainment) screen to display a message like "Battery Saver - System Off...", correct? I've seen this message intermittently over the last six years when turning the engine off. Sometimes the radio will continue to play until the doors are opened, other times that message will be displayed. I'm not concerned about that.
There have been no issues with starting, driving or any other normal functions. Just the big red battery symbol in the screen between the speedo & tach.
Assuming I replace the alternator, is there a significant difference in a new Motorcraft unit vs a Brand X reman?
Replacement looks pretty straightforward, if I can wriggle it around that lower radiator hose.

 

It's a waste of money to replace the alternator without checking the system. You need to see what the PCM is commanding and what state the BMS is in. The system is capable of 11.8-14-6 voltage and the alternator doesn't charge all the time. The system will show a battery fault if the battery temp, charge rate or cycle count is too high. You need to be able to see the BMS days in service with IDS, or using forscan force a BMS reset and watch the truck voltage PID. The hall effect sensor is known to go bad and its located on the negative battery cae near the battery.

 

IDK WTF IDS or PID mean, and I'm pretty sure I lost my forscan when I was a baby.

So I need the FORscan Lite app on my iPhone and an to really see what's going on? I'd like to think that the dealership would have looked at all these acronyms when they were trying to figure out the issue, but that might be wishful thinking?

 

I use a vivint usb adapter with CAN switch for the forscan much cheaper and easier. The dealership often doesn't go through the proper steps.

 

It's been a couple of weeks since I started this thread. The battery light has not come on again since then (although I was on vacation last week and did not drive the truck during that time.) I finally got a chance to plug the OBD Link connector in and ran the FORscan Lite app today. It retrieved the following error codes:

P0562 - System Voltage Low
Status:
- Previously set DTC - Not Present at Time of Request
- Malfuction Indicator Lamp is Off for this DTC
- Test not complete
Module: Powertrain Control Module

B10F1 - Key in Switch
Additional Fault Symptom:
- Circuit Short To Ground Or Open
Status:
- DTC Present at Time of Request
- Malfunction Indicator Lamp is Off for this DTC
Module: Body Control Module

U2101 - Control Module Configuration Incompatible
Status:
- DTC Present at Time of Request
- Malfunction Indicator Lamp is Off for this DTC
Module: Steering Column Control Modudule

B1596 - Service Continuous Memory DTC
Status:
- Previously Set DTC - Not Present at Time of Request
- Malfunction Indicator Lamp is Off for this DTC
Module: Antilock braking system


The P0562 sounds like the code that coincides with the Battery light that started this thread. I don't know if the other codes are related, or whether I should somehow clear these codes and monitor for future issues.

 

This past Monday afternoon, I was pulling away from a stoplight and the truck had almost no power. I thought the engine was about to die, but it kept going - just accelerating very slowly. I glanced down at the gauges, but there were no warning signs. That's when I realized the speedometer wasn't registering, the odometer was blank and the MPG readings were blank as well. I pulled into a parking lot and let it sit there running for a while, then decided to take a gamble and limp it to a dealership a few miles away (the same one that re-flashed the PCM for the transmission recall.) Made it there without issue, but the transmission seemed to want to stay in 3rd through 5th gears. They finally had a chance to dig into it this morning, and determined that it needed a LEAD FRAME CONNECTOR EXTENSION, which was covered under Recall 19N01 2.20. No charge to me.
Apparently this was not related to the battery warning light that started this thread. For that issue, they seemed pretty convinced it was the alternator, and gave me a quote of $1300 parts & labor. I told them thanks, but no thanks and purchased an alternator and two new serpentine belts for $425 at the local parts store. Took about an hour and a half to replace, and I didn't even bleed!
Hopefully that ends this saga.