Would anyone know why i would be getting a charge system failure on my display?
I'm showing 13.1 to 13.8 volts on my display. Any help would be appreciated.

 

Computer sees a lack in response or control from the alternator. For example if the computer tells the alt to charge more and doesn't see a timely response, you'll set a code/fault. Typically it's a bad connection, battery going bad, loose serpentine belt, or alt starting to go bad.

 

thanks. I'll check the belt and battery. its the original battery from 99

 

I've gotten this too from time to time and that's what I was thinking it was,, ALT or Battery..but my battery is also reading 13.8-14 so I am thinking it might be the Altenator

 

Pull it out and look for the old battery leakage

 

Here is how a C5 gen/altn. works:
The L-terminal circuit from the generator is a discrete circuit (a discrete circuit has no splices and only one source and destination) into the PCM. The PCM applies ignition voltage to the generator L-terminal circuit. A small amount of current flows from this circuit through the generator windings to ground to create a magnetic field which starts the generator process. When the generator is at operating speed and producing voltage, a solid state switch for the L-terminal circuit in the generator opens and the PCM detects that the initial startup current flow has stopped.

The PCM expects to detect low voltage on the L-terminal circuit prior to the generator rotating at operating speed and conversely expects the circuit to be at ignition voltage potential when the generator is operational. When the PCM detects a fault (circuit shorted to ground, or circuit shorted to voltage), the Driver Information Center will display Charging System Fault.

The generator has an input to the PCM called the F Terminal to indicate the percentage of total capacity that the generator is producing. This signal is detected by the PCM as a duty cycle from the generator and displayed on the scan tool as a percentage. The PCM can monitor the generators output under all conditions to determine if it is functioning normally.

When there is low demand from the electrical system on the generator, a low duty cycle percentage will be displayed. As more accessory load is placed on the generator, the duty cycle output detected by the PCM will approach 100 percent. A normally functioning generating system will never reach 100 percent as indicated on the scan tool.

The L and F terminals are the red and grey
I hope this is not too technical
Good Luck
Bill aka ( ET )