Maintenance Q&A
Bright lights and sparkling windows

By Paul Abelson, Land Line senior technical editor

Last year I had a problem with my trailer lights flickering in my 2007 Dorsey dry van. My local truck repair shop traced the damaged wires and replaced them. He also sprayed all the wiring to keep out corrosion. He did the spraying at no charge. Now the problem is back and any warranty has long since expired. I don't want to go through this every year. There has to be a better way. Can you please help?

Intermittent flickering of trailer lights is a common problem, mostly traceable to corrosion because of brines and road salts. Whether found at the nose box, inside the individual wires, at terminals, splices or connectors, it's usually because of a path that allowed road spray into the system.

The flickering usually occurs because connections are damaged. They can be eaten away by the corrosive chemicals so they no longer maintain steady contact. Because the wire is made of twisted strands, it carries moisture - and anything the moisture carries - through the wire. The process is called "wicking." That's why wire should never be probed or poked. All continuity and voltage testing should be done only on bare metal. Damaged insulation allows moisture in.

When brines and salts get into the core of wires through wicking action, resistance to electrical flow increases and wires can no longer deliver enough current to keep lamps bright. Voltage drop through high-resistance wires coupled with voltage reductions in batteries affected by cold weather contributes to lamps appearing to be burned out.

Sometimes wires can be replaced with an incorrect size or wire gauge. Using too small a wire (higher gauge number) can cause too great a voltage drop. Also, if your trailer was originally wired to be grounded through the chassis and your mechanic rewired it to take the ground back to the nose box, all the wiring should be upgraded for the added length.

For example, if you have 14 clearance and marker lights, each drawing 1 amp, and your trailer is 48 feet, the total amount of wiring is almost 60 feet. With a chassis ground, you likely had 12-gauge wire. By adding a white 10-gauge common ground wire, you increase the total length of current flow. So you should increase the brown 18 gauge by one size to 16 gauge. If it is 16 gauge, increase it to 14 gauge. (The lower the number, the thicker the wire.)

A corroded section can be cut out and replaced. Be sure you get all the corrosion and seal the splice. Undo the terminal at the lamp and follow the wire until it feels noticeably more flexible. Cut the wire at that point and inspect for signs of corrosion under the insulation. Because of the wicking, corrosion can run several feet from the terminal.

When the corroded wire is removed, splice in new wire, and slide a 2- to 3-inch section of heat-shrink tube over the old, good wire. Use the appropriate-sized crimp connectors. The best have heat-activated sealant. Strip away

1/4-inch of insulation and crimp both the connectors twice to the wire and the insulation. There are special crimpers that do both together. The best have a ratcheting action that releases only when a proper crimp is accomplished.

Apply heat to melt the sealant around the metal parts. Join the two ends, and then slide the heat-shrink tube over the splice. Apply heat to shrink it for a tight seal.

I like to cover lamp connections with liquid electrical tape, a brush-on vinyl insulation and sealer. It's watertight but cuts away when necessary.

Since your trailer is less than nine years old and trailers generally last for 20 years or more, consider rewiring with a sealed wiring harness and LED lamps. The combination takes lighting problems from one of the highest-maintenance cost categories to virtually nothing, according to a Technology and Maintenance Council member survey.

After a truck wash or even after I wash my windows, I have water spots or streaks on my windshield. Even worse, the area outside of the wiper blade reach seems to remain mildly dirty all the time. Is there anything safe for windows, beyond window cleaner and paper towels (which aren't always the most effective at removing streaks) that I can use to get a really clean windshield?

It's pretty easy to fall into a trap of thinking that if it's my truck, my cleaning supplies need to be automotive cleaning supplies. Not so. Some regular household items are as good, if not better, at cleaning your truck.

A perfect example is your windshield. Bar Keepers Friend soft scrub has been around - and by that same name - since 1882. It is a soft, gentle cleanser invented for use on delicate tile, mirrors and even glass. The abrasive material in it is just enough to strip away the grime and residue for that deeper clean, but gentle enough to not scratch your windows or mirrors.

Follow the directions on the bottle, or you won't get the results you're looking for. In short, you'll shake the bottle and apply the creamy mixture on the wet window or with a damp rag. After you rub it onto the window, leaving a white colored film, rinse thoroughly.

Once you dry the window, follow it up with a high-quality glass cleaner (sorry, dollar brands) and you'll have a really clean windshield. LL