So I've been having issues with sidelights blowing fuses under the dash (LHS) then deteriorated to blowing the lighting fuse under the hood. As suggested I started checking continuity from the outside in and found thereIS continuity between ALL the bulb power leads and their corresponding earth leads on the front sidelightsAND the front turn signal lamps. That isn't right is it???? (Even with the lighting switch completely disconnected)

I also decided to run the MFU test. I already suspected the lighting switch on the steering column but this continuity test would indicate otherwise, correct? and when I ran the MFU test everything beeped just fine except the sidelight switch. My question is that this still doesn't isolate whether it's the switch or a bad joint in the MFU does it?

Here is more wierdness, when I first checked the fuses a while back there was no 10amp fuse inserted in the MFU slot but everything seemed to work except the LH sidelights, howcould this be????

BTW my fusebox matches my owners manual diagram but is completely upside down compared to the RAVE diagram.

98 series1

 

you will get continuity unless you pull all of your bulbs. I would pull the fuse box and check for corrosion. I had a water leak and it ruined my fuse box. I had a few gremlins because of it. The truck would start and run on itsown.....