copcarguyp71

I will open by saying...sorry this is a typical newb first post but I recently purchased a used 2004 Silverado LS stepside standard cab with a 5.3 litre with 110K on it as a shop truck/runaround vehicle for our business.

The first thousand miles were fine but all of a sudden a few things cropped up and I am wondering as to possible causes and if they may be interconnected. In the message center I am seeing "check brake system" and "service 4wd"...these two appeared within a day or two of each other and now today the climate fan was very intermittent and the temperature controls were stuck on hot even though I had them set to cold. all of these things have happened within a week and I am hoping someone out there might have some insight as to any one of these or if they might be interconnected somehow. We build emergency vehicles so electrical troubleshooting is not a big issue for us but rather than starting from scratch I thought maybe I could get some advice here from the guys who might know the best things to look at first.

oldchevy

The temperature issue is probably a stuck or broken blend actuator. The other issue requires you to check the brake system for low fluid worn out brake pads, etc.

copcarguyp71

So...I dug in a little more tonight.

The fan blower motor started only working on high and none of the other settings which points to a resistor right? So I change out the resistor and still the same result so next I start taking voltage readings only to find out that every ignition powered fuse in the interior fuse box only has between 5.2 and 8.9 volts varying..OH NO! I checked battery voltage and constant hot voltages on all fuses under the hood and in the interior fuse box and they all measure at 12.56 volts. I checked the ignition relay in the fuse box under the hood and both 40 amp ignition fuses...all were ok.

So my question is where do those ignition fuses in the interior fusebox get their feeds from and what could be causing this radical voltage drop???? Any help here?