I’m preparing to order a new GMC Yukon and am sorting through all the options. I don’t plan to tow with it, but my friend says I should still get the tow package as it beefs up the truck. What’s your take on this?

-Tim Roberts, Dublin, Calif.

Tim, I’d also recommend ordering the tow package for several reasons. You might have no use for the supplemental electrical wiring and tow connector, but the hitch platform might come in handy if you choose to use a bike rack, cargo carrier or other plug-in accessory.

The supplemental external transmission cooler will better preserve your transmission’s fluid, potentially increasing transmission life.

In addition, the heavy-duty radiator will inspire confidence when traveling while heavily loaded over hilly terrain.

Plus, the Yukon will enjoy greater resale value and wider appeal for the next potential owner.

I just had my car’s “fuse link” replaced for the second time in six months. My mechanic can’t tell me why this is happening. It’s very inconvenient and costly to have this fixed. Please tell me why this is happening and how to stop it.

-Grace Putnam, Huntsville, Ala.

No problem, Grace. Let’s start by taking a look at fuses, why your car has them and their cousin – the fuse link – and how they can fail. Automobiles contain a variety of electrical circuits for starting, charging, lighting, accessories and so on. Each circuit, or group of circuits, requires protection from excessive current flow. This can occur because of a short circuit, added accessory loads or a defective component.

Fuses are the most common circuit-protection device in use. They’re a deliberate weak link and are designed to fail if excessive current occurs, protecting wiring, switches and components from damage. A modern car might have several dozen fuses, located in one or more fuse panels, isolating each circuit from another. If a problem developed in the radio circuit, that fuse would blow, leaving your lights and other accessories unaffected.

To provide complete protection, a large master fuse (or several of them) is used to protect the circuits leading from the battery to the fuse panel and ignition switch. Some vehicles use maxi fuses (a standard fuse’s chunky big brother) as a master fuse, while others employ a short length of fuse link wire at the originating end of the circuit. Fuse link wire is smaller in diameter than the circuit to follow, and has high temperature insulation to safely contain the potentially melting conductor.

Step one in solving your fuse link fiasco is to determine which circuit this link is protecting. Assuming your car has no added electrical accessories overburdening the circuit, we’ll look for an injury in the wiring, allowing contact with a metal object. A wiring diagram and some hands-on detective work are used to identify the circuit’s physical route and condition. My hunch is a difficult-to-see part of the circuit is chaffing against a metal object under the hood or instrument panel, causing an intermittent short circuit.

Brad Bergholdt teaches automotive technology at Evergreen Valley College in San Jose, Calif. E-mail him at under-the-hoodjuno.com or write to him in care of Drive, Mercury News, 750 Ridder Park Drive, San Jose, Calif. 95190.