2004 W22 blown ignition B 50amp fuse

I would inspect all major connections for a loose one.

Check all battery connections.

check the grounds.

That is a major sub panel fuse feeding those circuit and each circuit has its own fuse
The total of those circuit is greater than the 50 amp fuse
My uncle had the same problem on same chassis on a thor Serrano
We could not find the problem, turn everything on and it still did not blow the fuse
What I did was get a 50 amp self resetting circuit breaker to replace the fuse
That way it resets seconds after it trips
My theory was that it as something to do with the ABS system, which is also on that fuse,

I've got a better idea for you to start out with. Use a clamp on DC ammeter over this feeder wire. Then turn on ALL IGNITION 2 (accessories). Flip your ignition switch ON, then measure total current. How many amps? Write it down.

Leave Everything turned on (have the engine running if you wish)

Then

Cycle the jacks

Did it blow the fuse? If so, WHEN? When you first toggled the jack switch or after a few seconds? If instant failure, turn off accessories and test the jacks by themselves.

If the fuse blows when the trailer jacks are working, no big deal. Install a TYCO relay and 30 amp self-resetting circuit breaker. Fuses have a weak feature. They can get hot again and again and again, and anneal to become softer and softer. They can sag (you can see it). Then they'll break. They'll break under a 5 amp load if the wire shunt gets brittle enough. The trick is to not load the fuse close to it's capacity.

I didn't know the the slides and jacks didn't work until later,I had everything on in park when I released the e brake and put in drive noticed ac and radio went off then noticed abs light and rear camera and step didn't retract with engine running. Later tried jacks and slide,not working. Couldn't find anything loose or burnt. Next day bought new fuses it held, everything worked. Check everything for last 4 days still no problems. Wondering when and if it will happen again. Thanks for quick responses wish I had posted when it happened. Going to try breaker first. Thanks again for the help keep ideas coming.

Hi,

Because I push the alternator charging circuit *hard* I replaced the 60 amp fuse with a 50 amp self resetting circuit breaker.

Does that circuit use an eight gauge wire? If yes, it is too small of capacity. Feed the jack power with a relay. When manufacturers design chassis circuits they have NO IDEA WHATSOEVER that an extra, large load, is going to be powered. Or, to put it another way: Are you ready to deal with burned connectors? I say this from experience. The last one was yesterday. A Winnebugger. I showed Gabriel what to do and he installed a relay for the jacks, then repaired the melted and burned connections.

Fuse blew while running in park, dash air on high radio on, rear camera on, e brake on, foot on brake. Released e brake pull into drive that's when fuse blew to pull out of campground. Didn't know slides and jacks were on that fuse until we got to next campground later that night.

Short explanation:

Wiring is FUBAR. Take the load OFF that switch circuit using a relay or you're gonna pay through the snot box. Chassis wiring FUBAR overloading will cause connector and component overload and failure. I made a lot of money from folks who doubted this.