30 Amp fuse issue. It blows immediately.

[Willys 1]

I have a 1997 mercury mountaineer 5.0 AWD
ALL of a sudden all power windows, power door locks, power front seats and power sun roof just quit working.
Checked main 30 amp max fuse in fuse box in engine compartment.
Disconnected neg ground cable from battery. Neg battery post and cable connector had "some" light white powder and needed cleaning as well as the terminal. Cleaned it all up, plus added battery post and terminal protectors.
Fuse WAS blown.
Replaced with a new 30 amp max fuse.
When i tried to put the negative ground terminal back onto its battery post...
There was a very strong and fairly large group of sparks that shot off that post and terminal.
Blew the just replaced and new 30 amp max fuse.
Prior to this event there have been no issues with any of these power operated devices.
Probable Cause/causes please.

Thanks Folks...
Doug Nobles

 

[BrooklynBay]

Welcome to this forum! Your thread was renamed & moved into the stock 1995 - 2001 section.

 

[sehaare]

If you are blowing a 30 amp fuse immediately, most likely the wiring has a direct short to ground somewhere. It could something could have rubbed through the insulation or wiring could have gotten pinched somewhere.

Most likely this will be an easy fix but the problem will be hard to find. You'll need a wiring diagram, I assume that the 30 amp fuse does not power other smaller fuses (that would be too easy to troubleshooot) so instead off pulling those fuses you will have to disconnect everything that the 30 Amp fuse powers. Replace the fuse and hopefully it doesn't blow with everything disconnected Then connect each load one at a time. When the fuse blows you will know that the issues was with the thing that you just connected. Then you will need to inspect all the wiring going to the device causing the issue. If you don't have the time to do that then you can just leave that device disconnected, reconnect everything else and everything else should still work once you replace the fuse again (stock up on 30Amp fuses).

 

[domct203]

Start by checking the wires in the loom that goes from each door to the body. The constant movement will eventually crack old brittle insulation, and is a known issue.

Dom