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      05-19-2023, 06:24 PM   #1
kolopn
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[DIY] Electric Power Steering Conversion

Hi all!

This is my first topic, so hello everyone!

I wanted to share my latest project with You which was replacing whole power steering system from hydraulic to electric one. I had a issues with power steering pumps, leaking lines and even after replacing pump and reservoir I still saw some metal shavings in oil, so for me it was enough and I decided to go for EPS conversion. (How something can leak, if there is no oil in it ) I did this conversion on 2006 E92 with N52B25 engine. Everything is surprisingly simple.

Some informations in the beginning:
EPS was introduced in E89, so I managed to find some articles and technical documents on how it connect with rest of the vehicle. EPS rack itself has a module built in, so what we have to do is to connect power supply, and CAN wiring, so car can see the module. Then we will need to perform some coding, but everything is pretty straight forward, and in one day everything can be done. With this modification we can get also servotronic function. One important thing, for cars after as I remember 09.2009 there will be need for FSC code for Servotronic function SA216.

Parts needed:
- Electric power steering rack - best way is to get rack with parts of wiring included, it makes life a lot easier not to make electric connectors from scratch - I did this way)
- Around 2 meters of cables for power supply - mine were 16mm2 (get red and brown one for easy job),
- Around 3 meters of small in diameter wiring for CAN - we will need to connect PT-CAN (wake up line green with red stripe), and 2 Hi-Low CAN wires - they are wired together (blue with red stripe and red one),
- 100A flat fuse (From factory the B+ is taken directly from battery with 100A fuse, but we can use B+ connector under the hood which is not fused, so we have to add one) - to get everything clean, also special fuse housing can be used,
- Power supply connector - 61 13 9145405, with two 12 52 1436649
connectors,
- Wiring ends with hole (I do not know how to name this part - This is end of wire that you can put bolt through and attach to something )
- CAN connector - 61 13 8383300 with three 61 13 0005197 connectors,
- PC with INPA, WinKFP, NCSExpert installed,
- Shorter accessory belt - can be found in RealOEM,

Good things to buy with this conversion:
- Tie rods,
- Tie rods dust covers,

Step 1: Removing old hydraulic system

Basically there is nothing to show. You will have to remove everything from system - Resevoir, all power steering lines, power steering pump, steering rack, do not forget also to remove power steering radiator which is in front of all radiators. Also accessory belt will need to be removed due to steering pump removal - that is why we will need shorter one.

Step 2: Installing EPS rack

I had to remove sway bar to get this done - Rest it straight forward. There are two steering rack bolts - 56Nm + 90deg, and tie rods nuts 80Nm. (If you are installing new tie rods - tie rod to rack 110Nm).



Step 3: Power Supply Wiring

If you already made the wiring, connect the power steering connector to rack. Now you have to connect somewhere the B+ and ground wire. I took the longer path around intake side (I was afraid to get the wiring hot on exhaust side). There is ground connection point on the left rail - so ground wire can be shorter - something around 1 meter - just put the cable there and secure with existing nut. I wired the B+ over the engine inside wiring tray above engine (there you can split the cable in half and put the 100A fuse to get it invisible, but easy to get), and put the B+ end on B+ connector that is provided on right side of the car (EPS has always +12V because of KL30 supply line)

B+ connection from EPS (red wire) on right hand side of car


Flat type fuse that I used:


Temporarily placed fuse for test purpose (before I bought the special housing for fuse)



Step 4: CAN wiring

Connect the wiring to steering rack motor, and wire this like power supply (You can put the wires together as a one piece for clean look), and wire them also inside wiring tray over the engine, but go with them to DME box on the right side of the car. There will be need some soldering action - you have to find exactly the same colors of the cable and solder new wiring to them wire by wire.

CAN and Power Supply wiring temporarily placed


So find:
PT-CAN wake up line - green with red stripe
CAN Hi and low wiring (they are wired together from factory) - blue with red stripe, and red wire

CAN wiring that I made:


Secure everything with eg. Isolation tape. Close box and be sure that every lock is properly closed - there cannot be any water residue!

Step 5: Get car to one piece

Reassemble everything - so under trays, put the wheels back on - mechanical and electrical part is done.

Step 6: Coding

Firstly open INPA and try to connect to EPS module. It should be visible because the PT-CAN and CAN will connect with EPS module. In INPA note down your part number of EPS.

If everything is visible, open WinKFP and by using P/N from INPA reflash the EPS module and write to it new VIN number (your car VIN). With that correct VIN number will be visible by car.

Last thing left is to wrote $1CB FA code to CAS and FRM by NCSExpert - without that step the EPS will not be visible in NCS, and we won’t be able to code it.

If everything is correct, you can download the TRC file from EPS, and in line „Variantencodierung_1” type the correct car type eg. „E90”, „E91”. You can also use there NCSDummy to read, change and finally create MAN file. From my point of view setting E92 steering option makes the steering heaviest from all of options - Personally I am driving on E90 setting.

Coding:


Code everything and EPS should operate properly. If there is connection error with some modules try to simply recode it. EPS connects with DME, DSC, SZL, CAS, KOMBI, JBBF.

Useful links:
http://weblog.pac1.net/_Documents/14...escription.pdf

Cheers!

Last edited by kolopn; 05-20-2023 at 05:12 AM..
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      05-29-2023, 02:11 AM   #2
dj_aivan
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Hi,great guide but i have a question. Why VO is : S1CBA CO2 package
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      05-29-2023, 04:31 AM   #3
kolopn
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Hi,

EPS was available as a part of that VO package, so if you bought CO2 package you'll have EPS installed in car, that is why it's needed to input this VO to EPS appear in NCS. Without adding this VO code, there will be no coding available.

Also EPS as a part of CO2 package allow to have better efficiency of around 0.2-0.3l per 100km. In my case my N52 2.5l engine with 218hp uses now on motorway with 120-140km/h around 6.3-6.5l/100km.

Cheers!
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      06-22-2023, 07:32 AM   #4
planeta825
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Hey, thanks for useful guide. Question regarding step 4 - where do you exactly find those 3 wires? Are they in a DME box? Are they connected to something or how do I access them?
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      06-23-2023, 01:53 PM   #5
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Quote:
Originally Posted by kolopn View Post



Step 2: Installing EPS rack

I had to remove sway bar to get this done - Rest it straight forward. There are two steering rack bolts - 56Nm + 90deg, and tie rods nuts 80Nm. (If you are installing new tie rods - tie rod to rack 110Nm).



Hi, please could i confirm something, your pic shows an anti roll with a straight middle section (original item that's fitted with hydraulic powersteering rack), were you able to re-use this with the new electric powersteering rack?

How much clearance is between this straight roll bar and the EPAS motor? Did you have to modify the connector for the wiring to clear? Any more pics showing this?

I'm looking to fit aftermarket H&R bars to my epas e92, bit unsure if the front bar will clear the motor, looks tight! (stock bmw Epas specific bar has a curved section in the middle to clear)

Thanks!
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      06-23-2023, 04:17 PM   #6
kolopn
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Quote:
Originally Posted by planeta825 View Post
Hey, thanks for useful guide. Question regarding step 4 - where do you exactly find those 3 wires? Are they in a DME box? Are they connected to something or how do I access them?

Hi,

I found all three wires in DME box (They are easy to find, because in the box harness is clearly visible) - I simply remove a little bit of isolation out of those wires and solder EPS harness directly to them.
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      06-23-2023, 04:39 PM   #7
kolopn
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Quote:
Originally Posted by n0v0s View Post
Hi, please could i confirm something, your pic shows an anti roll with a straight middle section (original item that's fitted with hydraulic powersteering rack), were you able to re-use this with the new electric powersteering rack?

How much clearance is between this straight roll bar and the EPAS motor? Did you have to modify the connector for the wiring to clear? Any more pics showing this?

I'm looking to fit aftermarket H&R bars to my epas e92, bit unsure if the front bar will clear the motor, looks tight! (stock bmw Epas specific bar has a curved section in the middle to clear)

Thanks!
Hello!

So that's totally stock ARB, from stock M suspension - 26.5mm diameter - the smaller middle section is standard for every M suspension. Only M3 don't have it. I didn't change position of any connector. Only to mount the rack, I had to remove ARB out of subframe, otherwise it's not possible to mount the rack. It's tight fit - the connector for torque sensor is nearest to the ARB, but it's a little bit higher than bar itself, so I'm sure that at least M3 bar will fit. (During installation of new sway bars be aware of changing dynamic balance of the car - best is to calculate each stiffness of the ARB and with that you'll see if car will be over/understeering or more or less neutral.) Unfortunately I do not have any photo of exact distance between EPS and ARB.

Cheers!
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      08-17-2023, 05:17 AM   #8
damir1908
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what is the part number of the power steering rack You got ? New or used ?
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      08-26-2023, 03:47 AM   #9
kolopn
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I bought used one - 6785257.01 (Sticker on steering column side) - That's why I have to put new VIN number to EPS module via WinKFP.
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      08-26-2023, 06:31 PM   #10
Brandoch
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I don't understand why you would remove the best part of the e9x series.
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      08-27-2023, 05:41 AM   #11
kolopn
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I have several problems with my hydraulic power steering:
1. Steering rack itself - I had plenty of play in it, and it started to develop metal shavings into power steering fluid,
2. Power Steering pump - I have replaced this because it started to go loud, after replacing with refurbished one it started to develop oil leaks and started to go loud again,
3. High Pressure lines - After 16 years every line was a little bit wet near banjo connectors,
4. Very poor power steering during normal parking maneuvers - With electric steering rack I can park with one finger
5. Test drive in E81 with electric power steering - I drove that in very spirited way, and I could not find much difference (only wired thing that I had to learn is how to read understeer from electric rack)

Overall I was just bored of resolving issues with hydraulic power steering, and cost of doing it properly with new parts didn't make sense to me. For electric rack I paid the same amount of money as for used hydro rack, but I don't have any additional (potential failure) parts.

So just to summarize - main reasons were: heavy power steering for low speed maneuvers and cost of rebuilding hydraulic assembly.

Last edited by kolopn; 08-27-2023 at 01:12 PM..
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      09-02-2023, 04:42 PM   #12
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Finally someone did this!

Quote:
Originally Posted by kolopn View Post
Hi,

I found all three wires in DME box (They are easy to find, because in the box harness is clearly visible) - I simply remove a little bit of isolation out of those wires and solder EPS harness directly to them.
Hi, i was driving company bmw f10 car for a long time, and i was in love with its Electrical power steering, the feel and sharpness of it, dont understand people who says you cant really feel the road with EPS, when after a couple days of driving you are getting uesd to this fast reaction time, so you drive as sharp as a blade. Now i have e61 525d, with its HPS, it works fine, but has some wear noise and the steering rack itself makes squeaky noises, i was wondering can this job be donw on E60/61 series, and i hope it can be
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      10-04-2023, 01:48 PM   #13
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hello very good information i want to do the same to my car can u maybe post pictures off where i can find the can cables ?
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      10-04-2023, 03:07 PM   #14
kolopn
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You can find them in DME box under the hood. Basically as I showed on the picture, you have only to find cables colors that match color from EPS wiring. Everything will be visible, after opening DME box.
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      11-16-2023, 03:56 PM   #15
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Woah!! What an excellent write up. This post has now inspired me for my next big project on the car! (I'm already excitedly digging on local junkyard webpages to get a rack of my own)

Any other tips/tidbits you can share? Possibly a photo of how clean the engine bay is now that the reservoir & PS pump are gone.

Any increase in throttle response since there is less mechanical drag on the engine? How did you size up the new belt (P#)?

Last edited by Ughandi; 11-16-2023 at 04:04 PM..
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      11-16-2023, 04:51 PM   #16
kolopn
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Glad to hear that I inspired somebody!
To be honest, there is no difference in throttle response, biggest differences for me are ease of parking, and a little bit reduced fuel consumption. I have driven with EPS thousands of km (mls ) and I see no disadvantage of this system. Feeling of the steering is basically very similar even when pushing through mountain roads.

New belt I took from LCI E92 325i. I have pre-LCI, and EPS was not available there, but as far as I remember it was available on E90 pre-LCI. So full OEM+ mod
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      11-17-2023, 10:22 AM   #17
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Less things to fail & one less fluid to top up is certainly a *very* good thing!

I need to educate myself on the coding side of things so I can get comfy with performing the swap (and find all that software).

Thanks for the intel on the belt! I wonder why the LCI 325i is shorter than the pre-lci 328i (as I have)

Thanks for making this writeup!
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      11-28-2023, 04:56 PM   #18
panky
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incorrect part number

Quote:
Originally Posted by kolopn View Post
I bought used one - 6785257.01 (Sticker on steering column side) - That's why I have to put new VIN number to EPS module via WinKFP.
Hi can you provide the right part number for the stering rack. the one you provided, is not correct and showing the reference to some wheels of z4. cheers
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      11-29-2023, 05:13 AM   #19
kolopn
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Quote:
Originally Posted by panky View Post
Hi can you provide the right part number for the stering rack. the one you provided, is not correct and showing the reference to some wheels of z4. cheers
Sure! I provided number from sticker. I will post photo from the sticker from my another steering rack that I have, and it fit fine:

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      11-29-2023, 07:44 AM   #20
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Quote:
Originally Posted by kolopn View Post
Sure! I provided number from sticker. I will post photo from the sticker from my another steering rack that I have, and it fit fine:


thanks for the reply. I just did part search number from the latest sticker you provided. and I am getting EPS from e91 and not from e89. so did you switch your hydraulic steering rack to EPS from e89 or e91. the part number in your latest photo giving the result from e91 instead of e89. So I am not sure that you used EPS from e89 or e91
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      11-29-2023, 05:08 PM   #21
kolopn
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I used EPS from E91. As I remember correctly and I have checked this now with parts catalogue EPS is the same for e90, e91, e92, e93 and even e81, e87, e88, e84. Specific type of car is defined during coding.
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      01-17-2024, 05:00 PM   #22
Ivan D.
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Hello
I own an e90 335d and I decided to switch to an electric rack I did everything mechanically the car works but the steering wheel is heavy I can't code anything I enter 1CB and S216A VO/FA in the CAS module but the EPS does not appear in the other modules in NCS Expert..
I will be glad it if someone could help, thanks
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