'77 Fiat Spider Electrical

[ystephen]

Electrical problem on a '77 Fiat 124 Spider: first sign was the turn signals weren't working. Checked the fuses and the "I"
fuse was blown and when replaced immediately blows when the ignition is turned to the "on" position. However, none of the other
components on the circuit have failed to work--the oil pressure gage, engine water temperature gage, stop lights, etc. still
work without the "I" fuse in place. The car is over-heating also. The electric radiator fan does not come on. I have run
current directly to it and it works, so something in the line to the fan isn't working. I also did a check recommended in
one manual of the thermostatic switch by disconnecting the wires and then connecting the terminals together with a short
length of wire whereby the manual says the "fan should run," but it doesn't, and the manual doesn't say what that means.
I don't know if the turn signal and fan problems are connected or two separate problems. Any insight or suggestions would be
appreciated.

[TStark]

Horn likely doesn't work as well?

[toplessexpat]

Get your multimeter and start the really tedious job of continuity testing (the "beep" setting is really useful here) to trace the "I" circuit and see what its running... and find the short that's blowing the fuse.

I (and L) run the fan, hazard lights and a bunch of other stuff (like the seatbelt buzzer and cigarette lighter) as built by Fiat.

http://www.artigue.com/fiatcontent/Wiring_1977.pdf

[spider2081]

looking at the wire diagram fuse "I" protects the radiator cooling fan and the horns. I am not sure this goes through the ignition switch. At any rate there are 2 wires on the back of the fuse . One is violet it goes to the horn relay. The other is light blue it goes to the radiator cooling fan. THey are push-on spade connectors. You can pull them off one at a time and see which one is blowing the fuse.

[ystephen]

Thanks to those who responded for the advice. My '77 was produced in a change over year so some of the features fit the '76 and some the '77. On my car, the "A" fuse operates the horn and radiator fan. I've checked by pulling the "A" fuse and the horn stopped working while it does work with the "I" fuse out. Again, the peculiar thing is, the other functions on the "I" circuit continue to work (tach, fuel, etc. gages) while the fuse has been removed. I also find that the backup lights aren't working and wonder if they, the turn signals and fan are connected somehow.