# Upgrading alternator issues



## pohouse (Jan 26, 2009)

'03 GMC Sierra 1500 5.3L upgrading 105 amp to 145 amp. Plugs are the same. Will direct swap work?


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## 06Sierra (Nov 30, 2008)

You will need a 1" longer belt. I just ordered one from Alternator pros a couple days ago. I got a 160 amp for $120. Locally it would have been closer to $200.


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## Plowtoy (Dec 15, 2001)

I have never done this, but wouldn't an alternator from say a loaded up Yukon Denali of the same year of your truck work ( I think that would be the 145A you are talking about)? So then wouldn't the belt from the same type of vehicle work? A 5.3 is a 5.3 is a 5.3 right? (o.k., maybe a 5.3 is a 4.8 or 6.0, who can really tell by looking at them??) Maybe I'm wrong but I can't see GM making drastic changes on the assembly line for belt lengths on same model year engine family, that's just me though.

Farther more, a 145A should be more than enough for today's vehicles, even with all the plow accessories. I believe that today's vehicles use considerably less amperage than vehilces of years past. With all the lighting going to LED, and all the computers replacing relays, you shouldn't have any problems. I never use anything but O.E replacment alternators and batteries and have never had issues in not having enough power, the key is to have good functioning electronic's


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## vegaman04 (Dec 12, 2007)

Don't forget to do the "Big 3" upgrade too.


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## pohouse (Jan 26, 2009)

vegaman04;1544305 said:


> Don't forget to do the "Big 3" upgrade too.


Call me ignorant. Please elaborate on the Big 3.

Actually, the oem 105 amp alternator has been sufficient for the past couple of years. It went out though and left the plow truck (and driver) stranded. The only replacement alternator NAPA had on hand was the 145 amp. It's a physically bigger alternator, same mounts and plug though. And yes, you do need a larger serpentine belt. The 145amp was actually $10 cheaper than the 105amp. payup


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## blazer2plower (Nov 19, 2011)

Bigger wires power and grounds. Go with 2gage wires.


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## vegaman04 (Dec 12, 2007)

The "Big 3" is upgrading 1) alternator positive to battery positive, 2) battery negative to chassis, and 3) engine ground to chassis. Some people replace the factory wiring; others add additional cables to the factory wiring. I usually add to the factory wiring, by adding 2 gauge with soldered ends.


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## blazer2plower (Nov 19, 2011)

There has been a lot of talk of alternator and BIG 3 up grades can they sticky it somewhere


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