E85 Electric Power Steering Control Unit Resoldering?

[rhamberg]

Hello guys, first post here so be gentle :wink:

I recently got a Z4 E85 3.0i -04, love the car so far but as several others I have issues with the EPS.
I got the EPS light on the dash as soon as I turned the key, no power steering at all. A few times the power steering started to work after a while driving. Kind of the opposite of the sticky steering..

Connected INPA but got no response from control unit. All other units including steering angle sensor read out just fine without any codes. Did verify with a top-notch diagnostics reader at a BMW dealer that the EPS control unit was not responding. During the whole time outside temperature has been a few degrees C, so any heat related issue seems unlikely.
I have been replacing the battery and verified voltage on the red cable to the motor and green/white cable from fuse 22. Measured good ground on the black cable.
However when I heated up the control unit and steering column to 50 degrees C the dash light went away and the power steering worked just as it should. The EPS has remained working during a few cold starts since then but haven't been weather for a proper test drive here in Sweden, only got summer tires.
I connected INPA to the EPS control module and got one code, 6127 Error code 27: Lenkwinkel Testbedingung nicht erfullt. My german is a bit rusty but didn't seem to be a relevant code, probably from the glitchy connection. Deleted it and haven't appeared again so far.

Since ecutesting.com seem to offer a cure for my symptoms by rebuilding the motor/control unit and due to the temperature dependent broken/fully functional characteristics I noticed, I would suspect some bad soldering joint in the control unit.
I have fixed two other cars by opening control units and resoldered bad connections, and feel confident around any size through hole or surface mount components. Would be nice to save some $$, even though ecutestings lifetime warranty is tempting.

So finally my question to you experts, does anyone have experience from cracking open said or similar control unit and resolder any joints?
Does anyone know what exactly might be failing in the control unit, or do I follow a false trail?

If I go ahead with the operation I will off course keep you posted with the result

 

[Anmarube]

O idea about fixing your problem but have used ECUtestinga few times now and every time perfect this was on Ecu,s though.
Welcome to the forum btw.

 

[ph001]

I’m not aware of anyone thats has opened up the EPS ecu in here but I don’t think you have much to lose by giving it a go. Please be sure to put some pics up in here if you do.

Even if you don’t find anything, I don’t think it will affect ecutesting’s service.

 

[rhamberg]

As suggested by ph001, I confirmed that ecutesting didn't mind if the ecu was already opened. If they assess it as faulty and repair it they will still put the lifetime warranty on it
Great guys to communicate with by the way!

So with nothing to loose I will give the soldering iron a go as soon as the ESP dash light comes back on after my hack style heat treatment.
Until then, please share any knowledge about ecu resoldering you might have

 

[rhamberg]

Hey guys, didn't take long before the EPS dash light came back
So I ripped the ESP motor out, shoutout to the awesome instructions at https://www.newtis.info/ .

Gave it a go to find the error myself, but no success. However I took some pics and might just as well share them..

Went for a hunt for bad soldering joints, or anything that could be fixed, so I started to unscrew the screws on the top



Foiund nothing interesting, so I moved on to the motor itself


All looked nice, so put it back together. Moved on to the lids on top

Forgot to take a photo on the rear lid, a few spot welded plates to the connectors. All looked good
Tried the middle lid

Everything was covered in some soft moulding material, found no bad connections
Moved on to the last lid

Solder joints looked good, screws were tight


Nothing more to do other than to wrap it up and send it to ecutesting. Really fast and nice guys, got the motor back within one week, with shipping from Sweden. Motor looked like this

Obviously they found something I didn't under the middle lid.
Put everything back in the car and started it up, ESP light went out straight away and is now after 1000km still gone
5 stars to ecutesting, they really got their s**t together

 

[malkang]

hello
I have exectly same fault.
I live in Korea. so I have a problem to send my eps module to ecutesting.
do you have anything solution?

 

[rhamberg]

I got no other solution unfortunately.
Even though I had a look inside the unit I have no clue what they corrected....

 

[malkang]

thank you….
I must search more…

 

[MKZ4000]

I believe they ship worldwide but that may be cost prohibitive for you. Worth looking into though.

They also fixed my eps module

 

[paradiso3]

[ref]MKZ4000[/ref], could i ask how did yo remove eps motor?? I am looking for the instruction but no luck yet....

 

[rhamberg]

It's pretty hard to reach, but I loosened the 8 screws securing the steering column. Then I could twist the column enough to unplug and undo the motor screws and have the motor removed

 

[MKZ4000]

I got Ross at RBM to do mine so I don't know the exact procedure but hes's a dab hand at it. It can be done without removing the column but I believe there is a special pin to lock the steering column in place.

 

[yg54sg]

For anyone removing eps motor , you can remove it without steering column removal but you need to remove drivers seat then become a bat upside down with you head up to the pedals. Remove the E11 torx bolts on the motor I used a 8mm spanner end to crack them then a socket and u joint extension bar to undo as there is not much room to rotate . Unplug the 3 wires on side of motor then jiggle it until it’s loose you then have to pull it towards the front of car then as far against the speaker footwell as possible turning it and fish it out through the hole below it. Thanks to OP great thread my plan is to remove the motor from the control unit and then mount the control unit back on a custom bracket since I did the hydraulic conversion I want sport mode but don’t want the motor engaged.

 

[enuff_zed]

For anyone removing eps motor , you can remove it without steering column removal but you need to remove drivers seat then become a bat upside down with you head up to the pedals. Remove the E11 torx bolts on the motor I used a 8mm spanner end to crack them then a socket and u joint extension bar to undo as there is not much room to rotate . Unplug the 3 wires on side of motor then jiggle it until it’s loose you then have to pull it towards the front of car then as far against the speaker footwell as possible turning it and fish it out through the hole below it. Thanks to OP great thread my plan is to remove the motor from the control unit and then mount the control unit back on a custom bracket since I did the hydraulic conversion I want sport mode but don’t want the motor engaged.

Exactly this. I use an 8mm ratchet ring.
Including disconnecting the battery and waiting, then seat and steering wheel out, it is about an hour for me now.
Same to put back.
If it's a manual car then put a pad on the clutch pedal as you have to push it down with the back of your head to get enough clearance. (RHD anyway).

 

[portculisz4]

Yes, I followed enuff-zed's suggestion about seat and steering wheel removal. A tip though on the clutch perdal, it does need to be depressed to give clearance to remove motor. I removed the cheap plastic backstop (10mm) and replaced with a short 10mm bolt with a 3mm hole drilled through the head and then placed a piece of heavy guage wire through the hole. Depress the pedal to the new backstop and tie across with the wire to hold it down, saves trying to do two jobs at once

 

[yg54sg]

Brilliant, thanks for the tip re clutch pedal

 

[r3vmatch]

Hi,

Looking at image 20180303_213041.jpg , to my eyes it looks like there are breaks in the bond wires near the left / right corners, unless that is "by design" (which would be unsual to me). Perhaps this is causing the faults in the EPAS unit?

I am am Electrical Engineer by degree and experience and this type of mounting of a circuit in a housing was more common in the 1980s for use with 'hybrid' circuits, especially for high-frequency RF designs.

In this case it looks like a cost optimization to me, normally all of those ICs would be in plastic packaging and soldered to a rigid PCB that would have some connector attachment to the outside world (vs. bond wires).

 

[yg54sg]

@r3vmatch the picture you mention is very similar to the glow plug control unit on a 120D 2004 , thin strands of wire from the PCB to terminals , these break and then the glow plugs stop working I will see if I can find a pic of the repair I did.

 

[Rix]

So this seems to be an annual event around MOT time...

Took the car for an MOT, passed with flying colours, had a service done and brake fluid changed and they had to free up a piston anyway...

Car off ramp and the PAS light is on. No power assistance...

A quick bit of googling found this thread and indeed it seems like I'm another victim of module failure!

Took a quick peek under the column and not sure I like my chances of contorting myself into that position, seat out or not! Will take a more serious look at the weekend, spanners in hand! The NewTIS link seems to be dead so wondered if there are any other guides available re removal?! Wish me luck...

 

[enuff_zed]

If your code reader can’t speak to the eps ecu and the sport button doesn’t work then yes the ecu is goosed.
Take it off, send it to ECUTesting for £295 and get it back fixed within 4 days or so with a lifetime warranty.
A few simple tips which, if you are happy to pm me your mobile number I can WhatsApp you through the process.