Replacing the ABS/ACS Unit

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Replacing the ABS/ACS Unit

Post by g8jka » Fri 17 Oct, 2014 21:51

Just thought I would share my experience on my recent ABS / ACS problems.

I was having trouble for a few months with the lights being intermittent and occasionally when I was bringing the car to a stop the ABS kicked in and it sounded like the unit was buzzing and the pedal was vibrating. When going to Gaydon for the BMW festival the lights came on again and stayed on constantly ever since. With my MOT due at the start of November I needed to get the problem sorted quickly.

So firstly we started off by reading the codes with a C130 scanner hoping that it was just a sensor that needed replacing and not the unit which would turn out to be expensive. It came up with code 71 - the pump motor :(

This meant it wouldn't read any other codes as there was no communication from the pump itself, so this needed replacing. After reading past threads from members with the same problems it looked like I had 3 options, a new unit, repair of my current unit or a second hand unit with the same part number. The third option looked the cheapest although once replaced it would need coding to my car, but this was the one I went with as it was worth a try.

I purchased a second hand unit from a E46 produced around a similar time to mine with the same part number for £59. The unit came and was in great condition and the part numbers matched so we set about changing them over. Firstly we disconnected the old unit and plugged in the new unit, just to see if the new unit worked before disconnecting everything else. After plugging it in and hooking the car up to INPA ready to read and scan the codes we turned the ignition on and BINGO, the lights went straight out. We could see the unit now and read the codes to see if there was any more faults and fortunately there was none. We then changed the units over and bled the system with new fluid.

I don't know if I was lucky or not, but I never had to recode the new unit to match the car and we could see the history of the new unit through INPA showing it was made just a couple of months previous to my original unit. Its been on a couple of weeks now and the ABS / ACS is working as normal and I have not had any error codes since.

So if anyone has trouble with their unit I would suggest sourcing a second hand one first to see if it cures the problem. The old unit doesn't need to be removed to test the replacement, just plug it in to see if the codes go out and if they do you can go ahead with swapping the old one out and hopefully if your lucky it won't need coding to your car :thumb:
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Re: Replacing the ABS/ACS Unit

Post by Gazza » Sat 18 Oct, 2014 10:45

Great info, thanks :D

Moved to the Knowledge Base.

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