2004 W22 blown ignition B 50amp fuse

Ignition B is dedicated for chassis use only for a reason. And here we have a small ignition switch relay powering significant HOUSE loads as well as it's design capacity. Chassis circuitry is bare minimum capacity to cover it's original design specification. "Jeeze got my house batteries wired into the headlight circuit Cause everyone knows I don't drive at night". Keep chassis circuits original. When tapping chassis for charging tap between battery and fusible link or fuse then use a dedicated fuse solely for the house power lead. Did the people who designed this get past sixth grade?

Good luck Mex

As for the OP problem
I don't believe this is a wiring defect
Wear? Maybe, age yes
This is a 12 yr old RV,
My uncle traded his Thor , but the problem seemed to be related to the ABS power circuits, IIRC the abs power relay gets its power from this sub fuse B
And is the only circuit using enough power to reach the limit of the fuse the other circuits would melt wiring before drawing over 50 amps and blowing that fuse
Not to mention blowing their own lesser fuse first
The ignition circuit do not carry that much power
They control relays that switch the power circuits
And there are a lot of RVs out there on this W22 chassis
I think
An on going wiring problem would have been noticed and brought to attention
Find the per fuse for the abs and remove it for testing purposes

Hi Mex,

We will all be sending good thoughts your way.

My house battery continuous duty solenoids draw 0.88 of an amp each.

MEXICOWANDERER wrote:
Tomorrow night I will have the last internet connection until I am admitted to cardiac ICU.

ANY ignition signal anywhere can power relay coil 1/8th amp. Use a real breaker not a toy breaker. Solenoid shaped relay works fine for this job. Tomorrow night I will have the last internet connection until I am admitted to cardiac ICU.

I found it at the top. Directly across from the ign switch. Its probably part of the ign harness, in that it affects the jacks and starter system. Sorry I didn't make that clearer. Its the top shroud on mine. good hunting. It only happened when I put the wheel all of the way up to get out of the seat.

I removed bottom of colum checked wires didn't see or smell anything,but I will wrap harness with rubber as suggested. I would install a relay but not sure where or what to cut it into. Thanks for all the ideas.

Excellent find CM!

Remove the shroud under the steering wheel. Look for a large wire bundle that crosses a sharp edge. Located across the top. I used a bike inner tube to cover the sharp edge. Found this situation on two W-22's.

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.

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.