Breakaway brake switch issue, maybe?

[spoon059]

We were towing yesterday, was getting normal fuel economy heading down the road. The last 200 miles the fuel economy dropped by about 1.5 mpg. My first thought was wondering if the breakaway system had activated. I have a TPMS that monitors pressure and temps, the tire temps were about 8 degrees above ambient, so nothing appeared off. I manually applied my brakes and felt them grab, so I assumed everything was normal and maybe afternoon head winds had picked up.

Got to the campsite... my brakeaway plug was pulled and dangling. Put the plug back in and went to bed. This morning I checked the plug again, it was fine. First leg of driving this morning, fuel economy was still about 1.5 mpg below what I would expect. At the first fuel stop I checked again, the switch was fine. Filled up with fuel, second leg of trip was still about 1.5 mpg low.

I left the truck plugged into the truck the first night, so the 7 plug switch had power (I assume the entire night, not sure if my truck shuts off power after a while turned off or not).

I thought these brakes were self adjusting in reverse. I backed into the campsite night one, backed away from the fuel pump twice... but all three times the camper was plugged into power. 2015 Jayco Jayflight with Dexter axles.

When we got to the campground this afternoon, I unplugged the trailer while my wife checked us into our site. I backed into the site without any power to the trailer, hoping maybe that will cause the brakes to "Self adjust" in case one of them is dragging a little.

I didn't notice any lack of braking when I tried to slow down. It's a 9500 lbs travel trailer behind a CTD With exhaust brake, so braking has never been a worry of mine. Whenever I slowed, the brakes were fine. When I gave it a manual test, I noticed an immediate and obvious slowing from the trailer brakes, so even if something was dragging, it wasn't applying full braking. Tire pressure and temps are all normal. I don't have my IR gun to check hub temps, but if it was dragging for 8 hours I'd expect tire temps to be above normal.

Any suggestions?

[Grumpy]

I think if it popped out while towing you would have felt a large amount of drag immediately. I made a hard turn in a parking lot once, caught the cable, and we came to an immediate stop.

[Jagiven]

What does concern me is being able to drive with a pulled breakaway cable. When that breakaway cable is pulled it should lock your trailer brakes up. I was behind my parents doing probably 55 on a County Rd, when their TT brakes locked up. Theirs got yanked out by a farmer's irrigation system that was spraying over the road. It stopped my parents right now, 4 flat spots on their camper tires. If you were able to drive with it the cable pulled you have brake issues. Bad switch, worn out brakes, magnet issues, something is wrong. I would check your system over closely.

Back to the change in fuel economy, that could be an issue with the TV too.

[ARoamer]

A strong headwind can easily knock off 2-3 mpg. IMHO, If your breakaway is working properly you should definitely notice it being activated and wouldn't be going far.

[JFlightRisk]

The Dexter self adjusting brakes adjust going forward, unlike cars and trucks that do going in reverse.

I heard of a trick to see if there is power going to the brakes, and you check it standing still. Have an accomplice pull and reinsert the breakaway pin while you hold a compass next to the wheel. When there's power to the brake magnet the compass needle will swing to the wheel. No power, it won't move when the pin is out. Just a thought.

[mrmom]

First thought was the same as ARoamer - Change in wind direction caused the MPG change. Have seen this often on trips.

If your break-away pin was pulled and you were still able to tow, you have a brake problem or an open in the break-away system. Should have locked up the trailer brakes immediately. How old is the break-away switch? Is it possible that it is bad and not making contact when the pin is pulled?

[spoon059]

Originally Posted by ARoamer

A strong headwind can easily knock off 2-3 mpg. IMHO, If your breakaway is working properly you should definitely notice it being activated and wouldn't be going far.

I assumed it was winds, but there wasn't any wind.

The breakaway switch was definitely out when we arrived at the campground the first night. Not sure if the trailer brakes are just weak or what... Like I said, Cummins engine pulled right through with no noticeable difference, except the fuel economy...

[norty1]

If you had brakes applied by the switch being open, there should have been some serious heat generated.

If the TSPS system did not show heat a touch of the hubs should have.

[Route 66 Traveler]

Originally Posted by spoon059

When I gave it a manual test, I noticed an immediate and obvious slowing from the trailer brakes, so even if something was dragging, it wasn't applying full braking. Tire pressure and temps are all normal. I don't have my IR gun to check hub temps, but if it was dragging for 8 hours I'd expect tire temps to be above normal.

Define "Manual Test". Did you activate the breakaway switch and then move the trailer?

The brakes self adjust when moving forward, not reverse. In reading through your comments I believe your breakaway switch is either defective, not receiving 12 volt power, or your brakes are not working properly. With good operating brakes once the breakaway switch is activated the wheels should lock up, or at least cause so much drag that it would be impossible to continue driving.

You need to have your trailer inspected by a qualified shop to determine what the problem is. The decrease in MPG that you describe is directly the result of the relation to your foot pressure on the throttle, not dragging brakes.

[spoon059]

I have no idea what is going on... I suppose it is possible that the breakaway switch came out just as we got to the campsite, but that seems highly unlikely.

The manual test was manually activating the brakes to see if I felt a drag on the trailer. When I manually activated the trailer brakes, I felt it tugging at me.

My speed towing was set at 68 mph, the same speed that it is every year for this trip and the same speed that it was in the initial portion of the trip. I'm here asking for guidance, not condescention. The 1.5 to 2 mpg drop had nothing to do with speed, which has been consistent for 8 years of towing this camper with this truck towing this exact route. 11.5 mpg has been the standard. It's I95 from Maryland, through Virgina, NC, SC, GA and into Florida, then 301 to I75 down through western Florida. Pretty level, minor grades usually over bridges. It's a very consistent drive, milage has been very standard since we bought this truck and camper. High head winds will occasionally affect that mileage and it will drop, hence my thought that perhaps we hit some wind that I didn't otherwise notice. Perhaps that's all that it was... but I didn't notice any other symptoms that we would normally feel.

Thursday night at the campground I disconnected the truck from the trailer. We left the trailer disconnected overnight until we left Friday morning for our final leg of the journey. Friday morning I reconnected the trailer and everything seemed much closer to normal. Got about 11.2 mpg on that drive, which included hitting beach traffic in the last 40 miles or so. Until we hit traffic, our speed was 68 mph, just like normal.

If I get a chance while we're out on this trip I'll pull the hubs and inspect the brakes. Otherwise we'll look at them at home in the Spring. Like I said... I'm at a loss.

[Grumpy]

Fuel quality from your last fill up could also cause that.

[spoon059]

Originally Posted by Grumpy

Fuel quality from your last fill up could also cause that.

I considered that. All the fuel this trip has either been from truck stops (TSD Logistics card is AWESOME, by the way!!!) or once at the Buccees in Florence, SC (first time I've ever been there that it wasn't an absolute ZOO!).

The poor fuel economy stretched across 3 fill ups in 3 different states. It's really baffling to me. The only thing that remotely makes sense is direct headwinds... but I didn't feel winds when we'd stop and didn't get any other buffeting that you'd normally get in windy driving.

Hoping I get a chance to inspect the brakes before we head back out. 960 miles home at 11 mpg is 87 gallons of fuel, at 9 mpg its 106 gallons.

[Route 66 Traveler]

It sounds to me that your breakaway switch isn't getting 12 volts from the battery. Possibly a fuse has blown, or it wasn't wired correctly in the first place. One sure way to test it is to park on loose dirt, pull the switch and have someone watch the wheels as you pull forward. With good brakes the wheels should not move and skid through the dirt. Or you can use the compass trick:

Originally Posted by JFlightRisk

I heard of a trick to see if there is power going to the brakes, and you check it standing still. Have an accomplice pull and reinsert the breakaway pin while you hold a compass next to the wheel. When there's power to the brake magnet the compass needle will swing to the wheel. No power, it won't move when the pin is out. Just a thought.

The issue of fuel economy...an oxymoron when discussing RV'ing...has been discussed many times before. I can say that after 30 some years of pulling many TT's and a Class A with a Toad, getting fuel is never a rewarding experience when watching the dollars adding up. Years ago watching the gallons going faster than the dollars adding up was much more fun. Anymore I never worry about MPG's when towing. It is what it is and that's the price paid for an expensive hobby. My average MPG's always vary between trips, no big deal.

[craigav]

My thought on the fuel mileage is that some stations have a pump labeled "Diesel" but in the winter could be #1 diesel (or a blend) especially in the northern US. #1 is needed for very cold conditions and works well, except that you will get fewer mpg's. Some places have a "winter blend" with 50/50 #1 & #2

[TaftCoach]

X2 on fuel.

[Happy wife / happy life]

Originally Posted by taftcoach

x2 on fuel.

x3 !!

[spoon059]

I came from Maryland, so I already had winter blend fuel. The fuel we got was in Southern Va and Florence SC. I would guess they are winter blend too... but not sure why they would give me worse fuel mileage.

Again... same trip, same time of year, same route, same truck, same camper, same kids, same stuff. Oh well. I suppose it's a mystery.