Hyundai i20 2011 Magna Steering Hard/Grinding Noise/EPS light ON!!!

Hi, just 2 days ago, my car i20 2011 Magna variant (no ABS) has developed steering hard/grinding noise issues.

* Input voltages from Torque sensor to EPS MODULE are all OK.
* EPS MODULE HAS 3 CONNECTORS:
* 12V is available at the input connector of the EPS MODULE.
* 12V is available at the output connector of the EPS MODULE when IGNITION is ON or Start.
* CAN voltages are all OK.
* All grounds are OK.

Following are the diagnostic observations made with Digital Multimeter (DMM):
1. Red terminal of DMM is connected to one pin of the output connector at the EPS MODULE, and black terminal of DMM is connected to another pin of the EPS MODULE. Now, engine is running and all warning lights including EPS are OFF. A GRINDING NOISE LIKE METAL developed when steering is turned left/right, and steering is very HARD. Also, DMM reads about +-12v or less.

2. However, on the contrary, as soon as EPS comes ON, there is no longer GRINDING NOISE. This time only steering is HARD. Also, DMM reads about +-3V or less.

3. Continuity Test: One pin of the EPS MOTOR is connected to one terminal of DMM, and another pin of the motor is connected to the other terminal of DMM. As steering is turned about either left or right, at about +-30 to +-40 degrees, the DMM beeps indicating "continuity" throughout the MOTOR. As steering is turned full left or right, I think at every +-30 degrees appox. turned, there is "continuity".

4. Voltage Test: 12V is supply to one pin of MOTOR connector, and another pin is connected to red terminal of DMM which is grounded through its black terminal. Same process started and steering is rotated. At every about +-30 degrees, DMM shows 12V.

So, by reading values of DMM in both cases 3 and 4, it seems MOTOR is working perfectly.
Also, as observed in cases 1 and 2, it seems MODULE is struggling to assist the MOTOR (grinding noise and hard) when EPS light is OFF.
However, when EPS light is ON, only steering is hard and no grinding noise anymore.
Why is there grinding noise when EPS is OFF!!!! I guess when MODULE IS ASISTING THE MOTOR, there is grinding noise. So why is this noise happening????

Awaiting for inputs and suggestions. Thanks.

Another observation:
12V is supply to one pin of EPS motor and another pin of motor to ground.
Please note that 12V is momentarily (about 3 seconds) supply at the motor.
At this time, the steering is STUGGLING TO ROTATE (only about 3 degrees rotate) and it's SHAKING/VIBRATING.
Same case when polarity is reversed.
Show less

Post the wiring diagram of this system if you have it. I need to see what we are dealing with.

I guess the closest wiring diagram I referred is attached herewith below. 

Finding service info for your i20 is a little tough, as they never sold it in the States. But it sounds pretty close to an Accent. I found this MDPS diagram from a '14 Accent that halfway matches your description:

 

It sure sounds to me like the EPS module is attempting to run the motor, finding something about its operation it doesn't like, and defaulting to a failure mode. The grinding noise suggests a physical failure, rather than an electrical one. Are you able to get fault codes out of the EPS module?

Reading more service info suggests Hyundai doesn't advise servicing the motor or the module separately. Any kind of problem external to the steering column assembly means you get the whole thing. :silly: The only other check I would advise is lifting the front wheels off the ground and inspecting the front suspension for binding or other failures. Anything that could make the EPS motor work harder than necessary. With the wheels off the ground, try to turn the steering again. It should now move freely.

I agree that the grinding sound may relate to a mechanical issue...does it act up on right turns as well as on left turns?

Do you have an amp clamp to get a current reading of the electric motor when the grinding noise occurs? Does service information specify any current value? Otherwise, what is the fuse's amp rating?