My buddy has a 97 Yukon and just had a new steering box put on about 100 miles ago.. Here is the trouble, when driving it the steering feels kinda grabby and tight in spots and he was told it would clear up after driving it for a while :confused:

So what would cause this problem ?

Also the steering wheel is now off center and the truck dosen't seem to be out of allignment to make the steering wheel be off that much..

So is it possible that the steering wheel was not centered when the new box was installed and that is what is causing the steering wheel to be off center ?

His steering pump has EVO on it, it regulates flow due to speed to make turning easier or harder. Problem is they fail all the time. Just unplug the sensor on the lower driverside of the steering pump, you can get at it from under the truck, simply unclip it.

It is not very probable that the pitman arm is on wrong(indexing wise) as the sector shaft has 4 indxing splines of different shape than the others to correctly index it IIRC.

His steering pump has EVO on it, it regulates flow due to speed to make turning easier or harder. Problem is they fail all the time. Just unplug the sensor on the lower driverside of the steering pump, you can get at it from under the truck, simply unclip it.

It is not very probable that the pitman arm is on wrong(indexing wise) as the sector shaft has 4 indxing splines of different shape than the others to correctly index it IIRC.
I have heard it mentioned about some of these new trucks having some type of speed sensing steering systems but I don't know much about them..

If what your saying about this steering sensor failing is true wouldn't that make the steering feel jerky and stiff at different speeds ?

I drove it myself and it dosen't matter if your sitting still in the driveway or going 60 mph down the road the steering stays the same.. I never drove it before the steering box was changed but he said it never felt like that before it was changed..

There is a steering wheel rotation sensor or EVO sensor on the steering colume inside the vehicle just before the fire wallthis sensor is causing the problem. You can unplug it or replace it, it is easy enough to replace except that you need a Tech 2 scanner to read the voltage from the sensor in order to install correctly. As far as the wheel being off centered the front toe should be reset any time front end parts are replaced. Pretty simple to center the steering wheel. My .02$ :grinpimp:

Thats the pickup for it, the valve that causes it is on the pump and is what I was talking about. Mine just randomly would make the steering wheel really soft to turn when it was stiff in the middle of a turn. The other thing is that 96's with the same motor and electronics did no thave this valve. When I ever change the pump Im putting in a 96 one with out the adjustable valve of the 97-99.

So how would you go about changing this sensor ?

I'm guessing this would be a dealer part but any idea off hand what it cost ?

I have never replaced a p/s pump or a sensor in the pump for this problem and I work for Gm. I have probable replace 200 of the steering wheel position sensors inside the vehicle for this exact problem. The position sensor on the steering shaft uses a 5 volt reference when the wheels are pointed straight ahead the sensor sensor will be at .67 to .72 volts the voltage will go upto almost 5 when you turn the wheel one. This sensor is a 2 piece sensor and by turnning the inside sensor you can change the voltage reading when the wheels are straight, so if the voltage of the sensor is not as low as possible when the wheels are straight you will get the problem you are describing. The valve in the pump only does what it is told to do. My .02$ :grinpimp: