Electrical Problem

93 Jeep Cherokee XJ
4.0 H.O motor
Auto

Mostly stock except secondary fan, lift, and tires. I noticed there were a couple fuses blown and figured one was for the heater. When i replaced it and tried to turn on the heater, it pops the fuse again. Also the fuse for my dash light keeps popping. I'm not good with electrical, but have been told it might be a bad ground. I dont have an owners manual to look up to see what the setup on the fuse panel is even supposed to be. If anyone could help me out I'd greatly appreciate it.

It's doubtful a bad ground will blow the fuse. The instrument light fuse powers the instrument lights, the clock lights, the 4X shift lights, the tranny shifter lighting, the ashtray, the radio lighting and cigar lighter light.

Things that I have seen that have blown that fuse in the past are a clamped wire in the radio harness, the clock and the wire running up from the instrument lights fuse, the harness rubs through on a body seam. There are other possibilities, but those are the ones I've seen before.

The heater fuse blowing can be the blower motor itself, the resistor pack (speed regulator) for the blower motor. The resistor pack is the more common. But I have heard of bad switches in the slide switch or mode selector control. This problem can screw up your electrical all the way to the ignition switch, the connector and the brown wire at the ignition switch can get crispy and melt.

It is a pain in the rear job to troubleshoot things like this and you can do more damage, picking through the wiring behind the dash, than you do good. It is doable if you have some basic knowledge and are careful. It can get really expensive if you have a professional do it.

Pulling out the resistor pack isn't really hard to do, damage is usually easy to identify, the resistor pack (the speed regulation for the blower motor) sometimes melts into a glob and blows the fuse. One easy test you can make is to unplug the blower motor and see if the fuse still blows. Or if you know how to work an ohm meter, you can test the blower motor ohms, most motors are around 4 ohms, some a little less, none are zero ohms that aren't burnt up inside. You can also use your nose, a bad blower motor often has that burnt motor smell, ozone and fried varnish. A resistor pack meltdown often smells like melted plastic and/or ozone.

I've seen the transfer case floor shifter gear position light wires shredded by lever action.