i have a 2000 blazer that has a voltage drop. I thought i found the issue with the brake switch but to no evail. I have pulled all fuses with a tester in place and the light doesnt go out. I need help what should i go after now.

 

voltage drops to what? from what? when? why did you think it was your brake switch? what light?

 

I used a test light on the system. I disconnected the positive side hooked the tester to the cable and probed the battery positive side. When i started tracing down a voltage drop i was told by pulling all the fuses 1 at a time the light will go out on the tester when u find the short. It never did. When i messed with the brake switch the light would get brighter when the pedal was pushed. If this thing sits for more tha 6 hours my voltage drops around 3.5 volts. It has a new alternator and battery all from GM.When the system (charging) is tested it shows the voltage drop.

 

never heard that technique, but I'm not an electrition or mechanic.. you remembered the main fuses under the hood, right?

 

Yes i pulled everyone that would come out. Including the door panel as well.

 

I would find someone with a Tech2 or equivlent scanner and pay them an hour labor to diagnose the issue. Sounds like you may have a Gem module acting up but it is hard to say... good luck.

 

What is approx cost of a module. Are they easy to replace.

 

There is more than one... but that may not even be the problem. Hence the "TECH2" scanner. Not just a regular scan tool.

 

What is the actual amperage draw?

 

I do not know the exact amp draw. I am loosing voltage to the tune of 3.5 volts over an 8 hour period. I'm not sure what amp rating is on the battery if i did i could calculate the draw for an approximate amp loss.