GMC Yukon – Higher output alternator?


I’ve added a lot of offroad lights to my 1997 GMC Yukon. What options do I have for a higher output alternator or modifying my current one?


You have quite a few options for higher output alternators for your truck. It will be hard to be very specific because I don’t know how much power you need or which alt you currently have, but I’ll give it a try.

In your 1997 GMC Yukon, there were at least two alternator setups that I know; 105 amp and 140 amp. The 140 amp alternator is the higher output of the two and I believe all trucks with heated seats came with this option. I’m not 100% sure on that, but I believe that was the defining factor. At the least, you can check the RPO codes for your truck to confirm your alternator’s output.

I mention that alternator because the 140amp can easily handle a few extra amps being drawn from high output lights. However, if you’re putting more then x4 100w lights up front, running the stereo, etc you may see a dip in voltage, especially on hot days. When you “need” to jump up in alternators will depend on that exact load and the climate you drive in.

With the above in mind, there are a lot of companies that produced modified alternators. Below is a link to a recent discussion on the topic and there are a lot more on the site:

A lot of it comes down to cost and your ultimate goals. If you find an alternator that is much cheaper then others you’re looking at, it’s probably junk. There are a LOT of garbage high output alternators out there, so only buy a reputable source with a warranty.

Most important!! Upgrade your electrical wiring so it can handle whatever output you decide on. This is not just the hot wires, but the grounds as well. We have a LOT of topics on proper grounding on the site that I highly recommend you read if you’re not familiar with it.

When you have a chance, check out It’s a laid back group of Chevy / GMC truck enthusiasts that are always willing to lend a hand and discuss the hobby or meet for a trail run.

Best of luck!!

Master |