Check charging system

[jeffsk8r6]

I need help, I have a 2007 ST limited i Have replaced the alternator and the battery. My battery light is still coming on and I don’t Know what my issue could be. Everything is tight, cables cleaned, I’m just lost on what I need to check

 

[DILLARD000]

Inspect all Cables+Terminals at Battery + Alternator + MegaFuse + Starter;
need to be clean + shiny + tight without broken\pealing insulation.
Then do a basic VoltMeter check at BatteryTerminals:
* With KeyOffEnginOff, should read 12.2~12.7v = Older~Newer Battery.
If lower put Charger on Battery for 4hrs, then remove Charger, check again.
If still lower then Battery is bad or you have a shorted\draining circuit.
* With KeyOnEnginIdling, should read 14.5~13.5v = Cold~Warm Engin.
If lower then likely a bad Alternator or broken Wire\Terminal.

2004+later HEC InstrumentCluster is also a possible culprit; its a NotoriousFailureItem.

 

[Nick Mann]

Are you sure the replacement unit is working correctly and it is the correct one for your truck?

 

[jeffsk8r6]

After work today I’m gonna run a voltage test on it and check

 

[Doug Kaye]

my 2004 has two ground cables between body and frame, located roughly below driver and passenger door on each side.
If these are badly corroded this will cause the battery light flicker, and strange fluctuating voltages when doing the checks that Dillard mentioned. I was seeing 11v to 17v during idle. After replacing them, all normal again.

These cables are also on F-150s so seem to be common on Ford trucks.

 

[OLE442]

I had the same issue on my 2007 XLT V8 four-wheel-drive a few years ago I replaced it with a rebuilt unit from Napa auto parts, got it all installed and it still came up the same way that it was battery needed checked. So I took it all apart and took it back to the Napa, they checked it out. They said that it was putting out the correct voltage and stuff and that probably whatever sent the message to the dash was probably not working. He said it would still work I could put it back in or they give me another one… He gave me a new one I reinstalled it and it worked fine and is still going strong. It is a PITA to get to.