1984 Lakeland spider

[MYFIAT]

Need some help. I am busy modifying the dash on my 84, I have put in aftermarket gauges and things are great until I connect the power window switch and the fuse blows. As soon as I turn on the ignition switch the fuse melts. Any help would be appreciated.
Scott

[76was124]

Did the Window switch work before the gauges were replaced? If so, and the new gauges are all the same impedance (resistance) of the original gauges, my guess would be the obvious thought that something is wired wrong on the gauges, likely a ground wire on the wrong terminal, or paired with the + circuit wire on the new gauges.

One approach to find the problem is to disconnect the battery (both terminals), and remove the fuse to the gauges. Then using a good quality ohm meter, check between the circuit side of the fuse holder(side that doesn't connect to the battery's +12v ) and the car's chassis ground. You'll see 0 ohms or very close to it. Make sure you are making very solid connections. Remove one wire at a time from the gauges until you see the resistance jump to tens of ohms, or several hundred or even thousands of ohms. When that happens, that indicates the wire you just removed is likely miswired or shorted or that gauge is a problem. A wiring diagram would sure help though to know all the other wires are correct too. Keep in mind disconnecting a gauge even in a properly wired system would changed the ohm reading, so you want to see something drastic.

If you tell me the fuse amperage size, I could better approximate the resistance you should see. For example, if it a 10amp fuse....using V=I(amps) xR(ohms).. you likely will see much less than 1.2 ohms (12volts divided by 10 amps equLs 1.2 ohms)