Not enough voltage

My dash lights brighten and dim at random. This is also the case with my heater fan, I can hear the fan slow down and then speed up again. It acts like there is not enought voltage. I went and got my alternator tested at the parts store, they said my alternator is giving more power than it should.

I think this is caused by a bare wire coming into contact with the chassis some where.

What do you think this is?

A bare wire touching the chassis should blow a fuse.I'd say it's more likely a loose connection at a ground or power source.

Is there an easy way to test this?

The problem is more predictable when the truck has been off for a while (cold start.)

Is there an easy way to test this?

The problem is more predictable when the truck has been off for a while (cold start.)
Clean and tighten your battery terminals,tighten all ground connections and power connections,get a diagram and read it to see what circuits are giving you a problem and what junctions they have in common.If you are in doubt of a connection perform a voltage drop test on it while it is under a load.If you tell us the year maybe someone in this forum might know something that that particular model is notorious for.I have a 98 and the only problem I had was a bad ignition switch.
Good luck
Unbe

It is a

93 S-10

2.8l v6

standard transmission.