Here's a question for you guys ... I've got a 2013 1500 AWD with rack and pinion steering. When I'm on a sticky surface, like wet ashphalt, sealed ashphalt etc,. and I turn the wheel sharply while on the brake (ie parking lot maneuvers), the steering shakes. You can see the wheels will visibly pulsate. I've mentioned it twice to the dealer, but they keep dismissing it. "Oh the pump isn't filled up", "you needn't be concerned" etc. Bull plop I say. It sure doesn't feel "right", but has anybody else noticed it?

 

I have the same van, and it does not do that. Have you checked for codes? Do you have the factory size tires on it?

 

Factory tires. No codes. Only does it when I'm not moving though.

 

just a guess... it it only occurs when at the steering stops..... have the alignment checked... the toe setting in particular. (any feather edged tire wear?)

secondly, the toe out on turn or ackerman's angle may be out of spec. This is a steering angle that is buillt into the steering knuckle attachments to the tie rod ends. this is not adjustable...if its out something is bent

 

No, unfortunately anywhere in the range. It happens as I turn the steering wheel. If I stop, the pulsation stops.

No unusual wear on the tires, and it tracks straight.

This made me think of something. The transmission cross-member is pretty banged up from the PO. I wonder if the front end took a hit and caused damage somewhere.

 

Also, I came across this document. It applies to the 1999 - 2005 years, but it makes me wonder ...
(part #2 in the diagram)

 

Just from the bulletin title alone, this sounds like your problem. And even if GM swapped out the valve in the production line, it doesn't mean one still couldn't go wonky on you.

 

post a video. if the spool valve in the rack is leaking it could feed 2 fluid circuits and they could fight the direction change. if you ever seen power steering lines hooked up backwards...it would be a less powerful version of that.

a lot of old fords had a steering shake if the steering was moved from stop to stop multiple times with the engine off. but you could do stop to stop turns with the car running to clear itself.