Interior fusebox ignition fuses have low voltage 5.3 litre 4wd

2004 CHEVROLET SILVERADO
124,000 MILES
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COPCARGUYP71
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I have been getting intermittent "check 4wd" and "service brake system" warnings for about a week and over the weekend the fan motor started working intermittently.

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. 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?
May 22, 2013 at 4:34 PM
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SINBAD271
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You may have high resistance on the ground circuit you'll need a wiring diagram . Trace your ground circuit.
May 22, 2013 at 8:32 PM
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COPCARGUYP71
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Actually it ended up being the ignition switch. I had 12.56 volts into it and 8.7 volts out of it. Switched it out and everything seems fine now,
May 23, 2013 at 10:07 AM
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SINBAD271
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Outstanding you have found the component causing your issue. Some individuals get frustrated dealing with electrical. I did at first. It's very time consuming, but it is very simple once you understand what it takes to send a direct signal . Again congradulations.
May 23, 2013 at 10:22 AM