98 GMC Suburban Steering Problem

I have a 98 GMC Suburban with a perhaps a steering problem.
Normally, when driving on a freeway and turning on a clover leaf or a 90 degree exit ramp, one has to apply a constant force on the steering wheel to
keep the vehicle on the road.
What I seem to have detected is that when applying force on the steering wheel on the above, I seem to feel that the wheel is intermittently fighting me with a non-constant force as though it has a mind of its own. I only notice this at speeds above 45 mph. I dont feel this when driving at lower speeds like driving into a driveway or into a parking lot. It almost seems that the power steering pressure varies giving the feeling of a non-constant force on the wheel. This does not cause an out of control condition but would like to know if anyone has experienced this. When driving straight, the steering wheel seems normal.
Any ideas?
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My first guess, steering speed sensor, underdash, base of steering column at firewall.
Had the same problem. The same description that I had. Especially noticed it in cloverleaf ramps.
ME
************

leaf or a 90

steering wheel to

steering
intermittently fighting

own. I only

driving at lower

almost seems

non-constant
condition but

driving straight,

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would this be an electrical module or an electromechanical gizmo?
"Marshall" <MarshallDotLandisAtComcast.net> wrote in message

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I've never done the replacement, but looking at it I'd say it's strictly an Electrical setup that uses some sort of PickUp to sense the speed your are turning the steering wheel in relationship to the actual speed of the vehicle. At low speed, when parking, etc., it supplies more boost. At road speed it cuts back as it would be to much for the open road.. At least that's how I understand it.
And, if you have wide sweeping cloverleafs, like we have a few around here, yes, you can run them at 45. When I had the problem I noticed it at about 25mph in a tight cloverleaf. The steering wheel seem to just "Hunt" for lack of a better description. Scared the crapola out of my wife when it went the first time.
If nothing else, it's a place to start!
I'm sure one of the "Master" of the list can give much greater detail as to the replacement and actual function. Unless something has to be cleared in the computer, and I've never seen that mentioned, it only took a few minutes for our shop to change them out. Didn't even have to leave it. He just came out, crawled under the dash, and did the fix by replacing the part.
ME

the
It
of a

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You take cloverleaf exits above 45 mph? I would think your problem is that only two wheels are on the ground.
OUS

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OUS wrote:

    My 1989 4.3 has 400,000 + Miles. My TH700R4 is getting questionable (IE: ready for a rebuild).
    Here is what kills 4.3 engines: Low oil pressure: Either from being run low, or a bad seal/gasket. Head Gaskets: Usually 200,000+ Mile Engines, mostly 80's engines. Coolant Leaks, or loss of cooliant. Water pumps should be changed every 70,000 miles.
    In the last 12 years I have sold about 250 4.3 V6 engines. Mostly due to people driving with out cooliant or with out oil. No water cooled engine likes to be over heated or operated with out oil.
    4.3's use V8 water pumps. These water pumps have 2 "weep" holes. One on top, one on the bottom. when you get steam or a drip from either hole, replace the pump. They also tend to lose the water pump shaft barrings in remanufactored pumps after about 69,000 miles. As I was reminded a few moths ago when mine broke, and my destroyed my radiator, and fan shroud. Charles
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