When do you use your RV hazard flashers?

Travel around in the West's "hill country" and it won't be long before you happen across an 18-wheeler doing a hard climb with ‘warning flashers a'blazin. To most, it just makes sense. After all, crawling up a steep grade and traveling far less than “freeway speed,” giving a bit of a warning to the folks coming up from behind is no more than sensible. What about RVers?

Towing a big trailer or hauling up the hills in the old motorhome, at times our speed can drop below the "norm." Most of us are courteous enough (and smart enough) to pull over into the right lane. But do we turn on the hazard flashers to give a little additional warning to those behind us?

What about in fog? The National Transportation Safety Board (NTSB) found that in daytime fog conditions just running tail lights isn’t enough to give folks behind a good warning–in fact, turning on tail lights gives no more visibility than if they were turned off. However, the NTSB found that even the lowest rated hazard flashers could increase visibility. For example, if you’re driving fog where your rig could be seen 300′ to the rear, by turning on your hazard flashers you could be seen 450′–this with the least rated hazard flasher, in terms of light emission. It seems to make sense that using hazard flashers when moving slow or when obscured by weather.

Evidently not all states agree. In the Commonwealth of Massachusetts it’s illegal to use hazard flashers except when a vehicle stopped or disabled beside the highway. We're not ones to foment rebellion, and were not sure which states allow the use of hazard flashers on moving vehicles and which don’t. But we do know we’d rather “tell it to the judge,” with our rig in one piece, than to keep our hazard flashers off to not offend local statute and wind up with an 18-wheeler in our rear bathroom.

But there is a technicality: Many rigs use the same lights for hazard flashing as they do for stop signals. When that happens turning on the hazard flashers can lead to “pulsing brakes” on trailers. That’s because the brake controller "sees" the flashing stop signal circuit as a command to fire the trailer brakes. It can be a bit annoying, particularly if you have to “tune up” the brake controller intensity for your rig–kind of like your four-year-old grandchild when he first learns how much fun it is to shove gramp’s rocker back and forth: A real neck-breaker.

Here’s the "work around." For less than $20 you can buy a "pulse controller" from your RV supply store. Installed according to directions, the pulse controller will isolate your brake controller from your hazard light circuit putting an end to those pulsing brakes.