speed sensitive steering

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by MrShorty, May 10, 2007.

  1. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    '98 K1500 Suburban. Limited research suggests that GM started using a speed sensitive steering system starting in '97. Was it optional or standard? Would my '98 have it? If I do have it, can anyone explain basically how it works? Not trying to diagnose any problems, just want to know if I have it and get a basic idea of how it works.

  2. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    Went to the library to research this a little in Motor ('97-'99 repair manual). According to their application guide, '97-'99 C/K series (includes Suburbans) almost all came with the EVO "speed sensitive" steering system. 3500's and some '99's didn't. So, I'm reasonably sure I have it (for whatever it's worth).

    EVO=Electronic Variable Orifice. Basic principle of operation: There is a solenoid on the outlet of the power steering pump that controls a valve. At idle or slow speeds, the valve is full open, allowing maximum fluid flow and, thus, maximum power assist. As speed increases, the computer monitors vehicle speed and another sensor that tells how fast the steering wheel is turning, and sends a signal to the solenoid to decrease the opening of the valve. So at higher speeds you get "less" assist.

    That's what I've learned so far. Haven't got any farther other than to climb underneath and visually verify that I can see a solenoid on one of the power steering hoses at the pump.
  3. TrailLeadr

    TrailLeadr Epic Member 5+ Years 1000 Posts

    Will you be able to post some pics so that others may use it as a referrence in determining if they have SSS?
  4. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    I will have to see what I can do. It wasn't hard to see. I simply traced the hoses from the steering gear back to the power steering pump and there was the EVO solenoid.

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