the fuse for my gauges blew the other day so I installed another and it blew immediately when i turned on the ignition. I took the gauge cluster apart and I didn't find anything wrong. I have a feeling that this is gonna turn into a real PIA. What exactly causes a fuse to blow?

Hey MordacP,

A fuse blows to protect the wires and components in a circuit from being exposed to too much current. Too much current demand through the fuse can be caused by a short circuit or a component that is jammed. The extra current heats up the fuse and melts it before any damage can be done to the associated wiring or components. It's the cheap weak-link.

You didn't say what year or model car you have, but here's the circuits that feed off the Gages Fuse according to the 86 shop manual (they're all pink & black wires):

a. brake switch;
b. rally gage panel;
c. Audio alarm (blue box in the convenience center);
d. Instrument panel connectors C1, C2, and C3.
e. defogger timer relay; and
f. defogger control

If you have an ohm meter, the easiest way to find out if the wire has worn through is to disconnect the electrical connectors at all of these devices, and measure the resistance between any one of the disconnected pink and black wires to ground. If you measure zero ohms, you have a short in the wire somewhere; if you measure infinite ohms, then one of your components is grounding out internally.

If it's one of the components that's causing the trouble, then put in a good fuse, and one by one start reconnecting the various components and turn it on until the fuse blows again. You'll then have found the faulty part and can concentrate on what's wrong with it.

Thanks for the info. Right after I posted i went out and took a look at the fuse box. I found that the wire going to the gauges was pink and black so I went up to the gauge cluster and found the pink/black wires coming in on both sides. I used an ohmmeter to test continuity from the power source to all the bulbs and gauges. While doing that, I found a bit of conductor that had slipped between the plastic sheet and came into contact with another circuit. I shoved it all back into place with a flathead. I finished testing everything else and put it back together. Problem was solved!

If anyone ever has this problem, maybe you can fix it the same way i did.

EDIT to add: I verified that the gauge cluster was the problem by turning the ignition back on while the cluster was not connected. The rally gauges worked and the fuse didn't blow so I knew it was the gauge cluster.

[This message has been edited by MordacP (edited 04-16-2009).]