Electric jack blowing fuse

[lantanatx]

Picked up my new Jayco Jay Flight 23mbh yesterday and got home and could not unhitch because the electric jack wasn't working. It had blown the 30 amp fuse. Even when we replaced the fuse, the light worked but the jack didn't so I took it back this morning (70+ mile one way) and they swapped out the jack. We used the manual crank handle at the dealer to get it unhitched and they swapped out the jack while I ran some errands. Worked fine when I hitched it up at the dealer but 2 hours later at home - it moved about 1/8th of an inch and blew the fuse again.

Had to come into work this afternoon so my sister loaned me her car, so I just left it to deal with this evening. What is going wrong here? The only electrical modification I had made to the TT was adding a battery disconnect switch - could that be related somehow (it was always in the ON position)?

[colliehauler]

If they are having that many problems with the jacks (Jayco forum) I think I would just buy a aftermarket jack rather then spend the time and money on fuel to drive to the dealer and back.

[Hiking_Hunter]

colliehauler wrote:

Hiking Hunter wrote:
A bad ground doesn't make sense. A bad ground is a high resistance connection and would cause the circuit to draw less current, not more. It could make the jack motor not run, but wouldn't blow a fuse.

Check to see if the (new) leg is binding. A leg binding up (maybe only when it is flexed forward or backward) would cause the motor to draw excessive current.

A leg binding on two jacks in a row?

Yes. I think a bent/binding leg ia a pretty common problem. Also, the OP said he had seen in the Jayco forum where other folks were having similar problems (jack blowing fuses).

It's the first thing I would check.

[pira114]

I also wonder what type of Jack it is. Not common, but I've heard stories about dealers putting jacks on that can barely accommodate the weight of the trailer dry.

There's also a chance that it was bent. If it's slightly bent, it can cause too much friction and make the motor work too hard.

The other common problem is the jack being extended or lowered and not stopping the motor when it bottoms out. Although, that's not usually an issue on new trailers. Unless this thing had been moved on the lot frequently by an inexperienced person.

[colliehauler]

Hiking Hunter wrote:
A bad ground doesn't make sense. A bad ground is a high resistance connection and would cause the circuit to draw less current, not more. It could make the jack motor not run, but wouldn't blow a fuse.

Check to see if the (new) leg is binding. A leg binding up (maybe only when it is flexed forward or backward) would cause the motor to draw excessive current.

A leg binding on two jacks in a row?

[pira114]

Hiking Hunter wrote:
A bad ground doesn't make sense. A bad ground is a high resistance connection and would cause the circuit to draw less current, not more. It could make the jack motor not run, but wouldn't blow a fuse.

Check to see if the (new) leg is binding. A leg binding up (maybe only when it is flexed forward or backward) would cause the motor to draw excessive current.

With most of the new jacks, they have an internal ground as well. When you bolt them to the A frame, there's a star washer that needs to "bite" into the frame. Newly painted frames and washers not tightened enough can cause a weak ground. You'll still get power, but it's kind of pulsating. Causing the motor to work harder and blow fuses.

This happened to my buddies trailer when we repainted the frame. We didn't tighten, or "crush, that washer enough over probably too thick of a paint job. Roughing up the paint below it and tightening properly worked.

With an internal ground, you still have a ground wire. So lots of people miss this.

[Hiking_Hunter]

A bad ground doesn't make sense. A bad ground is a high resistance connection and would cause the circuit to draw less current, not more. It could make the jack motor not run, but wouldn't blow a fuse.

Check to see if the (new) leg is binding. A leg binding up (maybe only when it is flexed forward or backward) would cause the motor to draw excessive current.

[Dragonfly]

My new Airstream did the same thing. It turned out to be a combination of a bad fuse holder which allowed the fuse to gain and lose contact and power and, a too tight power cable which yanked on the cable containing the fuse, causing it to lose and regain power over and over, eventually causing a short or surge, blowing the fuse. A new fuse holder TIGHTLY WRAPPED, and extending the power cable solved it. I hope that your issue is as simple.

[kalynzoo]

My first motorhome had electric jacks. On an early trip, perhaps the first, I put the jacks down and blew the fuse. Replaced the fuse and the jacks came up, put them down again and the fuse blew. After a sleepless night I crawled under the RV and found when the jack extended it pinched a wire. Changing the wire run solved the problem for the life of the rig.
Hope your solution is a simple.
Happy Trails.

[dvitale300]

I bought a new Starcraft in February. I've found a couple of areas where the manufacturing was done poorly and caused wires to fray / strip and start blowing fuses. The first was the wiring to the water pump that some wizard decided to place directly under the metal frame of the furnace. After about a thousand miles on the road the fuse frayed, and every time I turned on the water pump - pop!

The second place was on the electric awning where some wires were sticking out of the track they should have been and rubbed raw and exposed - so the awning was stuck deployed. Luckily, I found the problem and fixed it with about 6 inches of electrical tape and put the wires back into place.

You might be experiencing something like this as you have a new trailer.

[lantanatx]

I can't measure anything right now - at work trying to make up the time I missed this morning. The bad ground sounds like a promising lead. What do I need to check to confirm that?

[pira114]

I'm gonna second the bad ground. Since it's new, I bet they didn't get a good bite on the star washer. Lots of paint to get through. Check that

[westend]

What is the measured voltage at the battery?

[lantanatx]

No change of directions. It literally blew a fraction of a second after I put my finger on the switch to go down. It was not run up too far or down too far either. I see on the Jayco owners forum some other people are having similar problems.

[GordonThree]

colliehauler wrote:

The only other thing is to make sure it has star washers that bite into the metal where the jack is mounted, that is the ground on the jack.

^^^ This. If you have a bad ground, jack will struggle and blow fuses. I went through three fuses before I discovered this. Pull the screws out, clean the contact between jack and frame, tighten screws. Presto 🙂