Ok when I step on my brake pedal you can see the rear wiper trying to move and I have continuity from the brake light wires to the rear wiper wires. so I figured I have a crossed wire between the brake and the wiper. So I went back to the rear wiper and tested all four wires to determine my ground and I end up with green and black going to ground. Now I’m assuming the black is my ground so I have green and black crossed. And I went to my passenger side brake light and tested the yellow brown and black and they all grounded. WOW…This all started from me trying to figure out what is draining my battery and then I ran into this cluster f**k!! And I have no idea where the wire bundle runs to get to the back of the blazer. No I’m thinking I have some crossed wires in that wire bundle running to the back. Now I was an electrician but I’m used to working on AC and high voltage. So I’m not that well-versed in 12 V DC so I guess I could be wrong somebody please help me out. now my battery jacked up and won’t take a charge I assume it’s from having this problem for a while. So I was doing all my electrical checks with maybe 7 or 8V. So I do know that I need a new battery.

 

Weird problems like that are almost always caused by one circuit feeding back through another because of a bad ground. I know you said you checked them, but sometimes a ground can test good with a multimeter, but lose connection with any significant current going through it.

If you want to give us the specifics on your Blazer, somebody can check a wiring diagram and give you better information.

 

Okay what specifics do you need it’s a 2000 blazer LT. 4-door, 4-wheel-drive with the 4.3L Vortec. And it has pretty much all the fixins. Climate control and powered seats and such.
Veteran Tom A? What branch? I was Air Force myself. OK thank you very much for the assistance with this stuff. If you need any other specifics that I could get for you let me know.

 

That should be enough info. Here are the wiring diagrams for the lighting circuit and the wiper circuit. As you can see, they share a ground at the left rear body corner. I would start there. I would suggest you remove that ground from the body, clean it up, and reinstall it to be sure it's grounded.

Thank you for your service in the Air Force. I am only a veteran of Blazer Forum, lol.

 

Lets get you fixed up. Before we start on individual wiring/grounds/power and all of that: have you ever had an interior water leak from say the windshield or the door seal where the carpet was wet, especially on the drivers side? Is the floor pan rusted through?

When you say that a wire is connected to ground, how are you measuring this?

BTW, I loved jacked up problems, the harder to figure out the better.

George

 

I have a few more minutes this morning so I can give you some more thoughts. Black is your ground on the motor circuit. Green goes through another motor winding to ground from there which is relatively low impedance so that’s why I asked how you are measuring ground, some continuity meters may beep at that low impedance winding to ground set up.

At rest dk green and white should have no voltage on them. Which one gets 12v or a crappy partial 12v when you step on the brake? Does the washer motor also start?

I asked about the water because this is probably a corrosion point with power wires shorting and when that happens for wires heading to the back, the bundle under the drivers carpet is suspect.

George

 

Hey George, I do recall a time years ago of that I said something to my mother about a puddle on the driver’s side floor. And I had recently brought that up to my mom about the floor being wet. and she said at that time that I told her that he, my stepfather had let the window open. I still to this day do not recall ever telling her that but she says I did. Yeah sure that’s all a cute little story and all, but it’s all moot because the driver side floor is wet right now. I pulled out the rubber floor mat and it’s wet to the touch…oooooohhhh boy!!!

 

I’ve never had to pull up my carpet in this truck so I don’t know how difficult it is to inspect but my guess is a bundle of wires with white or green powdery corrosion somewhere.


George

 

Well George I am just about to start attempting to remove some of the trim. And I know one thing for sure George I've never been the type of person that has the feel or touch to remove trim in 1 flipping piece. So wish me luck, 'cuz I will sure as he'll need it!!! I really appreciate all the help you have given me. Tyvm!

 

Just want to be sure that you checked the grounds at the two rear corners like Tom said first. Did you also check the resistance to frame ground from the motor and brake light ground wires? If all this looks good then the wet carpet theory is a high likelihood.


George