The Low Voltage test (P0562 - Battery Low Voltage) is measured at RPM greater than 380 RPM. It is considered low voltage when the battery voltage is less than 11.5 volts for 10 seconds. This will cause the battery lamp to illumunate. The Battery Lamp will turn off if the battery voltage recovers to 12.04 volts or greater, due to reduction of load, increased RPM or an intermittent condition.
The P-0563 Battery Voltage High error is monitored at engine RPM greater than 380 RPM and is considered to be high voltage when the Battery Voltage is 1 volt greater than desired system voltage.
The above is from the 2003 Powertrain Diagnostics Manual.
The P-2053 - Charging System Voltage Low error testing shows 15.1 volts as the normal charging voltage, with the battery sensed voltage 1 volt below the charging goal for 13.47 SECONDS to be an error.
I think the "normal" system voltage is around 13.8 volts, but can't find confirmation in the manual. From what the above shows (not much) I would think that 14.0 volts would be OK. If it is too high, there are a number of ways for the PCM to get this info. It is monitored at battery voltage and battery temperature; both will alert the PCM to look for signs of over or under charging.
Was this measured on an analog gauge, or a digital voltmeter? If on an analog (dial and needle) one, then 14 could be 13.5 to 14.5 (or possibly a wider range) volts.
Based on old technology for battery sales, a battery shouldn't go into service if it measures below 12.53 volts, but the real way to check it is to have it fully charged, verified by specific gravity measurement and then load tested. Today's sealed batteries prevent specific gravity testing, so we have to leave that up to the PCM to determine by other ways.
If it is not causing any error codes, I wouldn't be too concerned about the 14 volt reading; especially if read from an analog gauge.
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