Normal steering at low speed, loose steering at high speed

[josephballison]

Good Afternoon,

I have a 1999 Chevy 1500 Z71 (I will post in the build forum as well as I continue to work on it). It has turned into a bit of a project truck but there is something that I am having an issues diagnosing.

At lower speeds, say up to 20MPH the steering is normal, feels good ect, after that the steering wheel develops a lot of play, as in an inch or more. I have been told bushings, then a steering rack, power steering, control arms ect.

I am hoping to narrow it down though. Does anyone have any thoughts on this?

I hope you all have a Great Day and Happy Thanksgiving for tomorrow.

[SierraDually]

From 97 to 99 (I think), the power steering pumps had a dumb feature that was called "speed sensitive steering" or something like that. It was a good idea on paper that never worked out in real life. 

To find out if you have this power sensitive steering, find the power steering pump and if you have a wiring connector goin to the back of your power steering pump with 2 or 3 or 4 wires in it, then you have it. Try unplugging the wire connector going to the steering pump. Test drive. If that corrects your problem then it is that speed sensitive system that is to blame. 

Best to search the forums. I'm sure there's more detailed info on this problem than what I can give you from my memory. It's a fairly common problem to our trucks. I think your options would be to leave it unplugged or get a new PS pump making sure you get one WITH the connector because they come with and without. 

Also if you unplug the connector make sure you secure it out of the way with a zip tie or something. Don't let it hang near the accessory belt on the front of the engine. 

Btw, Is it a 4x4?

[2018GMC]

I have same truck with the speed sensitive steering. How many miles? You may need the common wear parts, pitman arm, idiler arm, etc. my truck needed these at 120k. At 180k needed a steering gear box. Now it drives tighter than new. If unplugging the speed sensitive steering doesn’t change the loose feeling then you have worn steering parts. A reputable alignment shop can tell you what needs replacing

 

the speed sensitive steering issue was when making a long sweeping turn between 20 and 40 mph the steering would suddenly jerk or overboost. The system was supposed to have over boosted steering at low speeds and lazy slow steering at highway speeds. 

 

When i had my truck tuned by blackbearperformence they modified the computer program to have a constant steering pressure at all speeds. 

[josephballison]

Thank you everyone, I disconnected the sensor and pretty much no change, so not sure if I will also need to replace the sensor, but I will have to bite the bullet and rebuild the front end of it I think. 

 

[Hog Rush]

96' power steering hoses will bypass the "speed sensor" crap. You just gut the little valve parts from the back of the pump and use new hose. Leave wire hanging. 

 

There re is a conversion pipe that uses existing hose, but that part costs more than just replacing with a 96' hose.