I just swaped out the telescopic tilt assembly from my 98 gs4. I used one from a 02 gs430 to my 98 gs400. My question is,is the steering ecu the same from a 02 gs430 on my 98 gs4? Can i use the one from a 02 gs430 to my 98 gs4? What would happen if i use the one from it?

 

Even better yet where is the steering ECU?

 

The steering ecu is (I believe) different in the 98 GS400 from the 02 GS430. The 02 GS430 should come with the L-tuned steering ECU while the 98 GS400 does not. Using the L-tuned steering ECU should be fine if you use it in the GS400.

 

09/97 - 01/02 (300, 400, or 430) use 89650-30570
01/02 - 05 (300 or 430) use 89650-30640
02 & 03 SportDesigns use 89650-30600

I believe the SportDesign steering ECU should be close to what the L-Tuned Steering ECU was (if not the same thing). All of them should be interchangeable though.

 

what do steering ECUs do?

 

does it get stiffer when high speed? i love that i hate how gs is so loose

 

I assume it works by controling the power steering pump. The pump would give a different amount of assistance at different times while driving to give a softer/firmer steering feel to the driver. The L-Tuned Steering ECU is said to stiffen up the steering a bit. My guess is mostly at high speeds because thats when I notice the loose feeling the most. When your cruising at 60+mph you dont want the lightest touch to move a whole car side to side. If the car could switch to less power assist steering at those times it would stiffen up the steering. Because the Sportdesign GS's received a diffent Steering ECU, I'm thinking it does the same job the L-Tuned did. But these are all just my ideas of how it might work.