GM-GMC: alternator, sierra 4x4, gauge face

Question
QUESTION: hey i just put a new alternator in my 99 gmc sierra 4x4 1500 and it is charging the battery at like 16 or 17 volts. it seems really high. the truck has power everything. if this is to high can it harm anything???

ANSWER: did you put a higher volt alternator then the truck takes? i think these trucks take a 120 volt alternator and there is also a 160 that can be put but that is only for vehicles mostly that pull trailers a lot or have aftermarket equipment that requires more alternator output... so i dont see a problem with yours but if it is putting to much out it could make the battery boil..

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QUESTION: hey thanks for responding one more question.  I checked the alt and it is charging the battery at around 14.9 volts but the gauge in the truck is reading much higher????battery leads show 14.4 and alt lead shows 14.9 dash gauge show like 17 Volts???? not sure whats wrong.

Answer
well gauges are just that gauges if you have confirmed that at the source there is no problem and in two areas seem to be similar in charging your gauge is probably just off... and you know what get someone with a scanner to scan the engine while running.. or pay the 40 dollars... that way you know and if it is the gauge then change the dash gauge face or just the module behind it that gives the readings... those things can go out too