[LH Lead-Foot]

There is a lot of good information in previous post, but you have some equipment like a digital multi meter but do you have an amp clamp? I have two from Fluke that are expensive, but one from PICO and the other is a digital read-out from craftsman. I checked and measure / tested it against the others...real close and I was surprised as many on the market are $25-$35.

When you have a fan(s) or any electrical device in a series circuit, even a bulb(s), when you turn them on, they have cold copper windings or filaments. There is a brief in-rush of current or higher amps, then quickly drops the amperage during the on or continuous use. Please take this into mind to make a list like you did and take an amp clamp and take an actual reading.

Fuses are thermal devices that open when they get too hot, but inside the cab is cooler than the engine compartment, and those fuses inside will open when hotter and the ones in a hot engine compartment.

Using your DMM to check voltage drop is "Best Practice" when it comes to making sure everything electrical is correct and will not cause a problem now or later. The thing to remember is the higher the amperage, the higher the voltage drop. A high amp circuit on the B+ side and ground side (Often Overlooked) will be closer to 0.500 volts. Low amp circuits will have or should have closer to 0.050 amps. A dedicated ground found on sensors to the PCM/VCM will go into the PCM/VCM, thru it, out one of 3 or 4 grounds to connector G100, should measure 0.400 max. This is industry standard for the PCM sensor ground circuits.

I agree that 1.0 volt drop or loss between the alternator to the battery is too high. If the battery is a top post, use the post first and connector second to see if there is a difference as this will show a cleaning is needed. If the battery is a side terminal type, go to the center bolt and then get under the cables rubber PVC cover and check again. Side terminal batteries can leak into the cable and will cause huge resistance and not be seen.

If it all adds up to more than what you alternator produces, yes you may consider a AD244 that is rated at 144 amps to 130 amps is what GM shows.

So, check actual amperage on main circuits you have or are concern with and write it down. Fuses will handle a temporary in-rush of higher current due to cold windings. Do not forget larger gauge wire for grounds everywhere including frame to bed, frame to cab, cab to back of engine, battery ground to engine, ground to front fender, perhaps a ground from engine to frame at front.

Then check and do the positive cables as well. I use dielectric grease on all connectors, bulbs, flashlight, smoke detector, digital multi meter, everything. May it's too much, but works for me.

The AD244 or the newer DR44G can be mounted on the vehicle with a little effort and 1 wire regulators are sold everywhere with a 14.8 volt set point and 2.5 second turn-on time after starting. I use alternator man.com

Remember the battery as well. A good battery in open circuit will measure at 12.8 volts. A battery with 100% state of health will only require less than 0.03 volt to charge it going down the road. GMs' new Load Shedding logic controls the alternator using PWM to reduce engine load for fuel economy, and a TECH2 will show this activity going down the road.

Best of luck. (See below)