well took car to a garage today cause of idle surging.well it was all fixed.while I was there I had them check the check engine light.he came up with codes for bad 02(no cat) and eld.Well awhile back i had some problems with my alternator it would turn on and shu off completely whenever it wanted.well with RonJ's help I thought I had it figured out.So My mechanic finds out the number 15 fuse alt/sp sensor was very loose and is hard to get the fuse to set right.My question is is that whats causing the eld to throw a code and why do I even get the slightest dimming from doing anything in my car.Im talking putting windows down or up headlights on/off just anything it drops like 0.1-0.2 volt.Not sure whats wrong but my batts in my car are both deep cycle high ah and res batts from xs power and I have an ho alt so not sure why anything should drop voltage especially like putting the windows down.please help its annoying.