EPS Electronic Power Steering :Solved:

Nov 10, 2018
23
7
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2011 BMW Z4 35i
When it rains it pours. Over the last couple of months my car has decided to make my life miserable. First the water pump failed, then the transmission pan decided to leak, then I found a cracked valve cover. So I went ahead and walnut blasted the intake ports when I replaced the valve cover. I no sooner got the damn thing back down on the ground and the power steering started to act up.
If I turn the steering wheel aggressively the power assist goes out and I find myself wrestling the wheel in manual with no assist. Most of the time it comes back on in a few seconds. Once it stayed in manual for a couple of minutes. Not a good feeling as you dive into a corner with assist and exit with none.
I have done some looking around and so far everyone is saying there is no repair just replacement of the electronic power steering rack and pinion. Which is pretty expensive. Has anyone else found themselves in this situation. Is there anything that I can check, ie grounds or control boxes? Or is it bend over time.
 
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Nov 10, 2018
23
7
0
Ride
2011 BMW Z4 35i
I have done some research today and this is what I have found out. There is and or was an extended warranty through BMW to replace the Electroni Power Steering Module which is built into the electric motor housing. I need to talk to my local BMW service rep and find out if my car will qualify.
I looked up the cost of replacing the whole unit and it's around $1500.00 give or take a few. This does not include shipping, programming plus alignment. So my guess is closer to $2000.00 to replace with new. I thought about salvage yard but this failure is a known defect that happens around 35,000 miles. I guess that makes me lucky to have made it to 60,000 miles. That just seems silly to put in a used unit only to have it fail shortly there after.
I also found a company in the UK that specializes in repairing ECM"s and Modules.Here is a link to the EPS information.

ECUTesting

Price seems fair at around 400 to repair the module but I have a feeling that shipping to and from the UK could add up.
Does anyone know of a company here in the US that can repair the EPS module?
 

fmorelli

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Honestly this is the first time I've ever heard of any EPS issues. Would you happen to have any references you could share relative to this being a common or known failure point?

Depending on the situation I may have access to people or information that is helpful, and glad to help if I can. Please do share additional information if you have it.

Filippo
 
Nov 10, 2018
23
7
0
Ride
2011 BMW Z4 35i
@fmorelli First off can I take just a minute to tell you that your build is incredible. The details that you have shared have been inspiring to me as I work on my car. Thank you for all of the information it has been very helpful.

The link I posted for ECUTesting above has a great article that explains all of your questions. Plus a nice how to video on taking the motor off of the rack. I also found a recall/extended warranty number 12V302000

one example of the Recall notice
 
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fmorelli

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Thanks @Glutton4punishment, I embarked on documenting my car's build mostly because of the absence of information on the Z4. While an N54 car, it has lots of little things that are not the same. We have a lot more going on with the car now, but I've not yet started assembling posts with updates.

Thanks - I looked at the link in your post, which did cover their approach. My guess is there is a component that is failing on a circuit board, which is common.

I guess what I was asking was, where has this failure been discussed publicly? I just haven't seen it. I don't think I've ever seen it on a Z4 forum. @RobbiZ4 do you know anything about this? @RobbiZ4 is our Z4 electronics wizard :).

Sorry to hear about all the other issues - what's your year/mileage?

Filippo
 
Nov 10, 2018
23
7
0
Ride
2011 BMW Z4 35i
I spent most of the day searching the internet for information. The recall/extended warranty was very easy to find on the web.

My car is a 2011 Z4 35i with 60000 miles on her now.

IMG_1480.JPG

When I first purchased my car.
IMG_1481.JPG

Recent Photo

Heres a list of things I have done so far.

New front ECD struts. Replaced by the dealer when I purchased my car.
Michelin Supersport +4 on 19 inch wheels
Modified drivers’ side MSport Seat. I am 6’3 250lbs and the stock seat was killing me. Took it apart and made some widening adjustments. It’s so nice now, no more bruised ribs.
New front brake rotors.
New brake pads front and rear.
Eibach lowering springs.
Stainless steel braided brake lines.
Reconditioned wheels with one replacement wheel. When I purchased the dealer fixed and replaced one of the badly curbed wheels.
Machined aluminum coolant elbow. Replaced the plastic fitting that tends to crack.
Stubby antenna.
Gloss black Kidney grills.
Door courtesy BMW logo lights.
Purple PowerFlex Polyurethane sway bar bushings front and rear.
Ball joint heavy-duty adjustable sway bar end links front and rear.
Billet Aluminum Rear camber adjustment arms.
Luxon Front strut tower brace.
Dianin stage 1 and later 2 tune.
VRSF Charge pipe.
Super Sprint center cat delete pipes.
Muffler modification.
ECS Billet aluminum oil filter cover.
Luxor Angel eyes.
Tinted windows.
Tinted Wind Screen.
Carbon Fiber Roll Bar Covers.
VTTO Billet Oil Cap.
Tuner Racing Monoball front control arm bushings.
New water pump and thermostat.
New OEM valve cover, flapper valve and VTTO PVC valve.
 
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Nov 10, 2018
23
7
0
Ride
2011 BMW Z4 35i
I ran the codes and came up with a 63F5/ not present EPS Reduction servo power due to supply voltage. This peeked my curiosity because one of the symptoms of a failed EPS module is you may not get any codes from it. So I started checking wiring and connections. Everything was checking out fine on the power side but the ground side was not checking out. Without a wiring diagram I could only go so far. I was looking on the internet for a wiring diagram when I read a post from someone with a left-hand drive car where he said his ground was on the left shock tower. He continued to say that right - hand cars could have the ground located on the right tower. That's when it hit me, did I forget to tighten the ground lug on my right shock tower. Sure enough I missed it.
IMG_E1483.JPG
 

fmorelli

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Good catch. And this continues @barry@3DM and my contention that the Z4 was designed by interns. What a stupid place to put the ground of the EPS ........

Filippo
 

Lurcher

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Apr 6, 2018
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Dallas, TX but soon to be Cocoa Beach FL
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2012 z4
Heres a list of things I have done so far.


Modified drivers’ side MSport Seat. I am 6’3 250lbs and the stock seat was killing me. Took it apart and made some widening adjustments. It’s so nice now, no more bruised ribs.

You have got to share this info, as I'm a little bit bigger and can only last in the seat an hr at a time....
 
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fmorelli

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Aug 11, 2017
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E89 Z4 35i, F10 535d
You have got to share this info, as I'm a little bit bigger and can only last in the seat an hr at a time....
Michael, one solution is to extend the time you can endure in the seat. The other solution could be getting the car to go faster :tearsofjoy:

Filippo
 
Nov 10, 2018
23
7
0
Ride
2011 BMW Z4 35i
You have got to share this info, as I'm a little bit bigger and can only last in the seat an hr at a time....

Considering you know how uncomfortable the seat can be when trying to wedge yourself into it. You will also understand my desperation and how sore I had to become to finally say to myself enough. is enough. Taking my seat apart and making the drastic measures I did was not an easy decision those seats aren't cheap! But I had a car that I had just purchased and I couldn't drive for more than an hour or even two days in a row. Something HAD to be done.
I'm afraid I don't have a lot of information to share. What I did was to watch a few video's on you tube on how to take the seat cover off to get an idea of what I was getting myself into. One of the hardest tasks was to release the seat adjustment switch cover. Once you get that off without breaking the retaining clips the rest of it is upholstery 101. As you take it apart take pictures of how things are tucked in here and there and where wires are routed. Its really not very hard to remove the seat cover. You will need to get yourself some hog rings and a pair of hog ring pliers so you can put it all back together when you are done. Once I had the bottom seat cover off all I could see at first was the molded foam seat cushion. For me one of the tightest locations of the seat were the thigh bolsters. More investigation reveled that there is a piece of appox. 8mm round rod molded into the foam thigh bolsters. This round rod is welded to the metal seat bottom and has no give to it at all. If your ass is wider than the cradle these two round rods provide I guess BMW figured tough luck. At first I tried to figure out a way to bend those wings out to give me more room but for the life of me I couldn't get a hold of them in anyway without ruining the foam. Heat would have made it possible but no way I could get heat to it with the foam all around it. In my attempts I had sort of split the foam around where the rod was. After fighting with this area I came to the conclusion go big or go home. I couldn't sit in the seat the way it was so something had to be done. I carefully sliced the foam enough to reveal where the rod was welded to the seat bottom and I cut the rod free with my die grinder. I then worked the rod loose from the foam and pulled it out. I did this on both sides. I know it sounds drastic and to be honest it was one of those do or die moments but at this point I had nothing to lose. Now all of this cutting and pulling left the foam torn in places so I used contact cement and repaired the torn spots. Plus to help it to hold its shape and to make it more firm I used duct tape to cover the foam and to reinforce it. I was worried I may have made it sloppy or flat and not form fitting. But when I got in for the first time I was very happy with the results. The back of the seat was much easier. Where the seat wraps around your sides they used the same 8mm rod to form the shape of wings that bruised my ribs. In my case those round rod wings were just to tight. It was easy to get a bar and bend those wings out an inch or two. I can still use the adjustments to squeeze me on the sides and hold me firm when needed. The whole thing took me an afternoon and I can't tell you how much better it feels.
 
Nov 10, 2018
23
7
0
Ride
2011 BMW Z4 35i
I made a mistake and replied here to a post that was similar.

$4000.00 for a complete replacement, ouch!
After having just gone through this all I can do is share what little I picked up a long the way. From what I can make out after reading up on EPS systems is they are pretty simple. Position sensor, electronic clutch assembly, processor and electric motor. High current draw can cause some terminal ends to corroded. Loss of power could disrupt the can buss communication. Another thing I can tell you is they are pretty easy to pull out of the car. Two bolts hold the unit to the front sub frame, two tie rod ends, the steering shaft coupler (don't forget to keep your steering wheel from turning once the shaft is disconnected, you don't want to damage your clock spring) and a couple of electrical plugs. If you don't move the location of the tie rod ends I believe you will be able to put it back into place without the need to have the front end aligned. So your decision to repair in place verses doing it out on the bench should be pretty easy. The link to the rebuild company has a great how to take your EPS motor off. The company I found in the UK can test and rebuild your EPS components. One of the symptoms was not being able to communicate with the EPS module. Your code is just that, no communication on the bus. I never made contact with the company but you may be able to ask them if your code would be one they would look for or not. From what I could make out from just poking around cost of repairs were around $400. It's the shipping to a from that adds up. Plus the time to ship is another concern. If you consider a used unit you will need to have some programming done for it to work in your car. Not sure how hard or expensive that would be. I found a used rack on EBay for around $900 but you have to ask yourself how long before you are right back where you started if you replace with used?
 
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