INTRODUCTION
Since the advent of hybrid electric vehicles, there has being a tremendous push by major automakers, towards the development of technologies, that would ease maintenance costs of owing such vehicles, as compared to their conventional counterparts (wholly gasoline engines).

One of such innovative techniques, has being to replaced all hydraulically operated power steering components, with an electrically controlled one.

These days, you see vehicles without a power steering pump, belt, pulleys, and hydraulic fluids on them. 

No need for fluids, belts, and even belt pulley changes.
What can be seen is just an electric power steering assist assembly, basically comprising of an 1) electric motor; 2) reduction gear; 3)torque sensor; 4) electric power steering module-EPS.

Using this Ford fusion 2010 as a case study
1.Owner drove through flooded waters in the island (depth of flood waters was above centreline of wheel)
2. After some days, noticed some terrible noise coming from the steering, when steering the wheels right to left.

INSPECTIONS/DIAGNOSIS
1. Got into the car to simulate the customer's complaint by turning the wheels in all directions.
Terrible noise confirmed coming from the steering rack region.

2. No malfunction indicator light on, especially that related to the electric steering system. I mean, there wasn't a P/S sign.

3. As long as I was able to stir the steering wheel, with some electric assist, that made me realised that the electric motor was functional, and the noise was a mechanically induced one.

4. Turned the driver side wheel inwards to exposed the steering rack assembly, especially the tierod boot(that rubber thing that prevents grits, and water from entering the steering internal column itself).

5. We discovered that the tierod boot were torn on either sides of the steering rack.

6. Not satisfied with what we saw, we decided to rip apart the steering rack when it was removed to thoroughly investigate why the noise.

7. Electric motor, and the torque sensor mounted on the steering rack were still intact.

8. Electric motor drive belt, and its drive pulleys were also intact.

RESULTS
1. Brownish/red colouration depicts product of corrosion (water + air/oxygen=corrosion).
This happened as a result of WATER INTRUSION.

2. Torn shaft boots was the ROOT CAUSED of the problem.
The torn boots, allowed water intrusions, which corrosion, and erosion via grits, debris, etc of the steering rack column(I mean the internal diameter of the column itself).

The water decreased all the grease on the solid spline shaft of the steering rack.

THE FIX?
Two options were tabled here:
1. Get a replacement used steering rack assembly
2. Disassembled the entire system as I have done, assess, and replaced only the damaged part, then lubricate.
3. Either of the options would work, depending on a customer's financial standing.
4. Installed the steering rack, and do a steering rack CALIBRATION, in order to aligned the wheels.



CONCLUSION
This writeup isn't just limited to owners of hybrid electric vehicles. It applies to conventional ones too.

Always ensure your steering rack boots are inspected during any shop visits, and before the raining seasons sets in.

Its absolutely easier to have those steering rack boots replaced cheaply, than have an entirely assembly replaced.



PS:
In some of the failures we've tackled, steering feel was hard to stir, just like you'd experience on non hybrid vehicles.




Regards,
Joseph(08066643532)
DW Nig Ltd
www.dxta.com.ng
Isolo, Lagos

Its a 2010 Ford fusion hybrid sedan car, with an engine capacity of 2.5L.

Before commencing any job on a steering rack system, ensure the steering wheel is positioned straightforward.

This would prevent the spiral coil inside the steering wheels, from excessively extending (cutting). If it cuts, your horn won't beep a second (won't work).
I used the driver side seat belt to strapped the steering wheel to the seat.

This was how the steering rack boots looked like when it was removed. You could see how widely ruptured it was.

Here's the rack, already for disassembled.
I was just curious to know what exactly was making that horrible noise.

Exposes most of the steering rack components.
A: drive belt.
You could see such a belt arrangement on CVT transmission systems on Hondas, Toyota, Nissans, etc.

B: electric motor gear.
In this vehicle, the electric motor is fed a 12V source, unlike Toyota highlanders we've work on, with about 54V going through the motor.

C: reduction gear from the steering rack solid shaft.
Its driven by the electric motor's small diameter gear, which transmit the output to the steering shaft for controls.

Looking at the exposed components, and the brownish colouration instantly tells one the root causes of this problem was water intrusion into the steering column.

Steering rack on a worktable

Just in case you'd want to listen to how the steering rack makes that awful noise, here's the link over here!

https://www.facebook.com/767933589982123/posts/2149874898454645/