after hours of reading this website for and answer with no luck. what is the process to checking to see if a front sensor is working i.e. volts tests? and how would one clean the sensor i looked for the sensor and i i could find was the line , do i have to take the rotor off to get to the sensor to clean it
One would check with a scanner capable of ABS diagnostics. The free Autozone one can't handle it. You should be able to get a decent deal on a Snap-On MT2500, now that all the tech are/have switched to the Modis.
Once you have an appropriate scanner, first look for codes. Each wheel speed sensor has it's own code for a failure. (ie; one code for a LF sensor prob., different code for RF , and another for Rear sensor) You can also view live sensor data. Obviously, if you are on a straight, dry road and one sensor has a different speed than the other(s) , then it's not working right.
I would also check the wiring carefully from the wheel up to the plug by the front bumper. Both of my front sensor wires got torn somehow. No, you can;t just splice them back together. It won't work, as the slight increase in resistance, even with a good splice, will mess up the data from the sensor. This will cause erratic ABS operation and/or codes.
To address one of your other questions: You can't clean them. The sensor is bolted into the hub. Despite what some other people will tell you, it's almost impossible to remove a sensor from the hub. The sensor seizes to the hole in the hub, and it usually snaps in half when you try to remove, w/ half staying in the hub, with no good way to get it out. Yes, you can buy just the sensor/wire pigtail if you look hard enough, but they are just as expensive, or more then just buying a complete hub assembly (which almost always comes with a new sensor/wire already installed- if it doesn't- don't buy it).
Besides, it's not the type of sensor where "cleaning" would have any improvement. It's a magnteic pickup type sensor. The only thing that could mess it up, which you could clean, would be metal shavings attached to the magnet. But, if that's the case, then your hub is going bad anyway.
This is one of those times when you need the proper equipment to accurately diagnose a problem. Of course you could pay a shop to read the codes/offer a diagnosis, and do the physical repairs yourself.
