You came close to doing my trick for finding shorts. Instead of a jumper wire across the fuse socket, use a 12-volt light bulb. A 3157 brake light bulb works well. It will allow you to power-up the circuit without wasting a lot of fuses, and that bulb will limit current to a safe one amp. When the short is present, it will do the same thing a door switch does for the dome lights. The test bulb will be full brightness and hot, so be careful where you lay it. I made a test harness out of a right rear Dodge Viper harness where I could plug in up to five bulbs in parallel depending on how current needed to flow in the circuit under test. It was long enough to reach down to the fuse box, and to be hung from the rear-view mirror. You'll need to be able to see the test bulb(s) from where you're working. Now you can unplug things, wiggle connectors, move wiring harnesses around, or anything else that might affect the short. When you do something to make the short go away, the test light will go out, flicker, or become dim.
These drawings show each step of the process. There's probably more included than you need, but this might help others researching this topic.
The head light switch is not a good suspect even though smoke came out of it. There's usually no ground wire connected to it. Any smoke is likely to be the result of the excessive current flowing through it. If anything were to short internally, you'll typically have lights that won't turn off. Head light, dimmer, and heater fan switches are notorious for riveted terminals burning up due to stress of constant very high current, but that overheating adds a lot of resistance to the circuit. That's the opposite of a short. Bulbs will be dim of not turn on, and the heater fan will run slow or not at all, but that won't blow fuses.
One good place to start is looking for frayed wires in a trailer harness. The "Gauges" fuse feeds the instrument cluster. On later models there was a ribbon cable where the cluster gets pushed down onto the connector. That would be a dandy place to find mice have been chewing. If something there is shorted, the test bulb may go off when the cluster is pulled out.
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Friday, September 17th, 2021 AT 6:01 PM