Electronic Power Steering is violent and erratic after motor replacment

[CarnieZ4]

[https://www.youtube.com/watch?v=ZpBhmJ1ESNM]
*UPDATE: added Youtube video.
So... my 2003 BMW Z4 had the Electronic Power Steering Module intermittently failing, especially on hot days. Lots of digging on forums indicated that the EPS motor/module is the likely culprit. Codes:
EPS MODULE FAULTS:
- 6128: Vehicle Speed (173,736km)
- 611D: Power Supply (172,320km)
- 610e: Temperature EPS (186,760km)
- 6124: Power reduction due to overtemp (186,760km)

Well, I bought a replacement EPS motor/module, pulled the steering column, removed and replaced the EPS motor/module, and reinstalled the steering column. Now the fun part.
I hooked up the battery and started the engine. As soon as I touched the steering wheel, it began VIOLENTLY and ERRATICALLY shaking back and forth. All electrical connections are hooked back up.
Can't seem to find anything about this problem on forums. Any ideas?

 

[enuff_zed]

1. Any codes?
2. Does it fail?
3. Did you make sure the new unit was aligned as closely as possible to the old one?
4. Are all three plugs properly fitted?
5. Was the replacement unit definitely working properly when you got it?

Sounds as though the motor is getting constant inputs.
This could be due to the alignment pushing the gears too tightly together. Or it could be that the steering angle sensor needs to be recalibrated.
I replaced a column for someone but we retained their motor. The angle sensor had to be recalibrated before it would work properly.

 

[CarnieZ4]

[youtube]enuff_zed,
1. **UPDATE: Code 611B (fault not currently present): EPS: Steering Angle remains persistently after EPS module replacement.
2. The EPS motor has not failed (yet) it's just a violent steering motion generator.
3. I made a chisel mark for alignment where the motor joins the steering column separated by some kind of . I can't be certain if the new motor is EXACTLY aligned, but I can confirm it is very close.
4. The 3 plugs to the EPS went in with no issues. They were clean, with no corrosion.
5. I got the new EPS motor/module from an outfit in the UK that advertised it as new old stock. It came wrapped in some heavy duty plastic. I don't think they had a capacity to test it.

More observations:
A. When I first start the vehicle, the steering does not move on it's own.
B. As soon as you put ANY input to the steering wheel, it begins turning rapidly and violently in 1 direction, while I was resisting the turn (with heavy leather roper gloves). When it gets to full stop, it reverses direction, also with me resisting.
C. If I let go of the wheel, it begins rapidly oscillating about 20 degrees of travel.
D. I haven't been brave enough to just let it continue, I afraid its going to physically break something. I have shut it down within a few seconds of starting this wild rodeo.

Given the interaction between my input to the wheel and the terrifying outputs, I think I do need to find:
1. Motor alignment procedure.
*UPDATE: I figured out how to loosen the bolts that hold the motor to steering column. I rotated the ECCENTRIC RING between the Motor and Steering Column all the way from one extreme to the other, and several mid-points. ( This is the procedure usually called for in "sticky steering"). No change in steering behavior. Still violent and erratic
2. Steering angle sensor calibration procedure.
*UPDATE: I have an iCarsoft tablet that allows me to perform an electronic calibration at '0'. This was done. No change.

SO NOW - I'm at a loss. Either the part (New, old stock) is bad, or I forked something up on the steering column.

Any ideas?

Also, I took a video of this whole thing. I need to figure out how to upload that here. [*Update: Added video to top post]

 

[enuff_zed]

I have to say that this does look like a steering angle sensor issue. If you can see live data it should show a steady movement from -540 to +540 degrees as you turn the wheel.
I appreciate this won’t be easy for you. Not sure if it is possible with just the ignition on and hauling the wheel round?
I think the relevant plug is the lower one of the two at the top. Worth checking there are no bent pins

 

[CarnieZ4]

A service item in the iCarsoft tool after setting steering angle to '0' provides live data after the alignment.
I showed smooth reporting of angles from center [0] to full left [+545] to full right [-556]
There is still a remaining code:
611B EPS: Steering angle (Fault not currently present)
This fault was not present prior to swapping the EPS motor.

I pulled the 3 plugs going to the EPS, and found no bent pins.

Feeling kind of stumped. Any chance there is a configuration difference between a UK EPS motor (right hand drive) and a US EPS motor (left hand drive) ?

 

[enuff_zed]

Someone in the states just had their motor repaired in the UK and it went back together with no issues.
Was yours repaired or an unknown condition one bought?

 

[CarnieZ4]

I purchased it from an outfit in the the UK that represented the part as "new, old stock".
So I assume the part is intended for UK RHD.
Anyone know if they would be a different configuration from a US LHD part?

 

[enuff_zed]

I purchased it from an outfit in the the UK that represented the part as "new, old stock".
So I assume the part is intended for UK RHD.
Anyone know if they would be a different configuration from a US LHD part?

When you look at the motor it has two sets of bolt holes which I assume are for left and right hand drive

 

[Jodd]

@CarnieZ4 - very interesting to read your post.

I replaced the steering rack and motor last year, and got exactly the same problem as you. My combination was a steering rack from US and a steering motor from UK, which I paired together. I also fitted a brand new steering angle sensor.

I have not been able to figure out what causes the problem and the car has now been left useless for some time.
However, I have bought a third power steering motor from US, which I will fit when inspiration comes back to me

 

[Ciosorn]

@CarnieZ4
I have the same issue as you, but opposite:
I have a RHD motor on a LHD steering rack

If you want I can trade you my motor for yours, so that we both get the correct one c:

 

[enuff_zed]

Just dawned on me! The motor fits the other side of the column. So has to rotate the opposite way!
No idea if it’s codeable im afraid.

 

[Ciosorn]

@enuff_zed
Yeah I figured it out, when you touch the steering it behaves like a motor with following error, I've got some experience with those

 

[enuff_zed]

You could try contacting ECU testing in the UK to see if they know how to swap from RHD to LHD. If it’s even possible.
I know they have repaired a US motor so they must have dealt with both handed versions

 

[Ciosorn]

They said it is not possible to swap it
Do you know if there is a mechanical difference or only a software difference on the two types of motor?

 

[enuff_zed]

They said it is not possible to swap it
Do you know if there is a mechanical difference or only a software difference on the two types of motor?

No idea tbh. Possibly the motors all spin the same way, but the worm gear is the opposite thread?

 

[Ciosorn]

I hope so, at least I just have to swap the rotor between the two motors.

If it is coding, I don't know how to check it

 

[CarnieZ4]

I purchased it from an outfit in the the UK that represented the part as "new, old stock".
So I assume the part is intended for UK RHD.
Anyone know if they would be a different configuration from a US LHD part?

When you look at the motor it has two sets of bolt holes which I assume are for left and right hand drive

My EPS Motor does have 2 sets of bolt holes, and did come from the UK. (My car is US, LHD).

 

[CarnieZ4]

@CarnieZ4
I have the same issue as you, but opposite:
I have a RHD motor on a LHD steering rack

If you want I can trade you my motor for yours, so that we both get the correct one c:

Ciosorn,
It sounds like we have an identical configuration. My car is US, LHD, my EPS motor is UK, RHD. I would be have been happy to, otherwise.

 

[Ciosorn]

@CarnieZ4
Did you manage to fix the issue? Or is it still like this?

 

[Ciosorn]

I was also thinking about swapping two phases of the motor to electrically invert the direction of rotation, hoping that this would fix it.

I will update this evening and do a recap of everything so that it is left as a resource for everyone else