[DeTomaso] New Electrical Problem

tony DiGiovanna tonydigi at optonline.net
Tue May 8 23:22:39 EDT 2007


30+ years of wrenching and I just had a new experience that blew my mind:  I
put new horns in the car last fall.  All worked fine for a while and then
soon the horns stopped working.  Tonight I got around to diagnosing.  I
confirmed there was 12V on the red wire to the relay.  I jumpered 12V to the
wire headed to the horns and got the expected beep.  I confirmed the horn
button was properly grounding the primary.  Duh, it should be the relay then
right?  Half a dozen tries with another relay, etc. and it still didn't
work.  Long story short:  The 35 year old 25 amp fuse had become resistive
enough to prevent the relay from energizing, but it would not blow as the
horns don't draw enough current to do so.  I do not have the AC in the car,
so the higher draws for that fuse circuit do not exist.  I changed the fuse
with a new 16 amp unit and all works fine now.  No, the fuse had good
contact in the fuse box.  I had checked that already.  Damn, if that aint
the strangest thing.




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