DIY: Do It Yourself
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|08-01-2013, 03:46 PM||#1|
Join Date: Aug 2012
My Ride: 330Ci
Replacing a faulty ABS module
This is the first time I have posted on the forum so will try to make it a good one. First a big thanks to all those who have taken the time to post their knowledge and experience on the site as this has helped us out here to learn how to solve technical problems that older BM’s occasionally suffer from... It is now time to give something back so I am writing up my experience in changing a faulty ABS/ASC/DSC unit on my 2001 330Ci.
Any wiser folk out there please feel free to jump in and correct any of this.
The fault first appeared as an occasional flagging of the ABS/DSC/brake amber warning lights. These would appear when the ignition was turned on and remain on for the length of the trip. On the next trip the three lights would turn off after travelling 20 yards or so and then remain off. Initially this would be once every 3 months but progressively got worse until the lights would come on every other day.
A BMW 1.4.0 scanner and software was bought of e-bay which was easy to install (on Windows XP) I am a very average PC user. The ABS fault codes were read several times over the weeks and wheel sensor (sometimes 2 at once) and pump failure codes were randomly flagged. I was able to check the wheel sensors with an oscilloscope and these were found to be working.
Reading up on this it seems that problems with the MK60 unit are known, in order to replace a faulty ABS unit several important steps need to be taken.
1) The replacement unit must have the exact matching part numbers.
2) The replacement unit will need coding so that the ECU knows which model / spec. of car it is fitted to. The ECU records the VIN number and vehicle running order (a list of modules fitted to the car) from other modules fitted to the car.
3) The unit needs to know the straight ahead position from the steering angle sensor (a fault will be flagged and the DSC/brake warning light will show if this calibration is not done)
4) The braking system needs to be bled, there is an additional procedure to bleed air from the ABS control valves and pump.
In order to code the unit and perform the ABS bleed procedure a diagnostic cable and INPA / NCS expert software (INPA version 5.0.2 NCS expert 3.0.8) was bought from here http://bmwcables.co.uk/order.html Please excuse this link – I have no affiliation with them but the cable and software worked just fine so this information was included in the hope that it helps someone.
BMW dealers want a huge sum of money for a new MK60 unit plus fitting so I was determined to find and fit a second hand one. A second hand unit was bought off e-bay for £80 that was sold as ‘in working order with no faults’ – a bit of a gamble but then it is only a little more than the price of a tank of fuel so worth taking the chance.
At this stage I would advise that you only attempt coding after you have read up on what you are about to do. It is all too easy to screw things up if you start experimenting! so take it easy.
I decided to try coding the replacement unit before fitting it to the car – if it got screwed up at least the original sort of worked and the car was mobile. There is a very helpful write up here; http://bmwcoders.com/forum/diy-guide...s-module-1063/ this was used to code the unit. Thanks to MaxVQ. There were a few minor differences in the procedure as the write up was done for an E39, these are listed below. There is some additional information on the MK60 unit here; http://bmwcoders.com/forum/3-er-8/bmw-e46-256/ scroll down to find ‘bmw-tsc.pdf’. Thanks to ac427.
1) Step 2 - I had to use ‘code control unit, allow ZCS reading’ rather than ‘expert mode’
2) Step 5 – Select E46
3) Step 6 – There was an error message selecting IKE but worked selecting EWS
4) Step 9 – Select ASC
When complete you can check the coding information if you run INPA software, select F3 (E46), select ‘chassis – DSC MK60’, select F2 (identification) your cars VIN along with other data should now be displayed.
Set the steering angle position using INPA by the doing the following;
1) Run INPA software
2) Select E46
3) Select ‘chassis' – DSC MK60,
4) Select Shift F4 ‘Abgl.Rout.’
5) Select F1 (compensation steering angle initialisation VIN Nr). Ensure that the steering is set to the straight ahead position before you hit F1. A warning written in German will be displayed, this briefly translates as an error code will be flagged if the steering angle is more than 30 degrees form straight ahead when the calibration is performed. Accept this warning and the steering angle initialisation will commence.
6) The final step was to check and clear any fault codes.
The main harness was re-connected to the original unit still fitted to the car and using INPA, the ABS bleed procedure was tested. I had not found a write up on this but selecting F6 ‘Activate’ then press F2 (E46 ASC/DSC rework bleeding brake calliper LF/LR) activates the ABS pump and cycles the valves so this seemed ok.
The faulty MK60 was removed and the replacement unit fitted, this was the easy part of the job as I have years of experience (or is that wasted life) turning the spanners.
Bleeding the system:
I worked around all 4 wheels bleeding the braking system in the normal way starting with the caliper furthest from the master cylinder, first with a vacuum bleeder then by pumping the brake pedal 3 or 4 times to check that no air remained.
With the laptop connected and a helper sitting in the drivers seat to press the brake pedal and operate the laptop;
1) Run the INPA software
2) Select F3 (E46), chassis – MK60
3) F6 (Activate)
4) F2 (E46 ASC/DSC rework bleeding brake calliper LF/LR)
The procedure that worked (though I do not claim that this is the proper / best way of doing this) The F2 button was pressed and the brake pedal pressed. The software runs the ABS pump then operates the control valves. After the pump stops and as the valves begin to operate open the bleed nipple on the left rear caliper – brake fluid can be seen pulsing out of nipple. When the valve activation routine stops and the pedal has gone down to the floor shut the bleed nipple. I did this twice and then bled the caliper in the normal way – no ABS activation and pumped the pedal until no air came out of the system.
The same procedure was followed for the left front caliper.
A similar procedure was followed after pressing F3 (E46 ASC/DSC rework bleeding brake calliper FR/RR) on the right side of the car.
The brake pedal felt firm even after running the above ABS activate routines a further couple of times.
I went for a careful test drive and found a quiet area to test the ABS this had plenty of space if things went badly, all was ok.
Finally grab yourself a beer, I had several - and think of what you can do with the cash you have just saved – only don’t tell the misses!
My searching suggests that the fault with the ABS/ASC/DSC MK60 unit lies in the circuit board, with time, vibration and thermal cycling solder joints can crack causing these intermittent faults / warning lights. When time permits I will open up the faulty unit and investigate. If I find anything helpful I will post the information.
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