Hi guys,

I need help PDQ!

I have had to replace the abs pump on my daughters E46 compact. Got a second hand unit from FAB.

I swapped it over easy enough, but as soon as I reconnected the battery the pump began to run uncontrolably, depsite the keys out, engine off.

My problem is I don't know why this should be, and am returning home on Saturday and need to get this sorted asap.

I am wondering if, seeing that the new pump is empty of brake fluid, could it be trying to prime itsfelf, as did not get as far as bleeding the brakes up, not wanting to have to do this twice if the pump if faulty.

All help very much appreciated.

John.

Update, been trawling the web and there seems to be a lot of posts pointing towards the ABS relay failing in an energised state, thus causing the ABS motor to run till it fails. This sounds logical, but were the heck is the ABS relay?

Message me your VIN ;)

Sent you a pm, cheers, John.

You have the N42 engine if that helps...

Right, did you disconnect the battery before changing the unit? If not, Naughty boy !!

Your next job (and most important one) is to fill and bleed the system, the noise you heard was the unit in "Self-Test" mode, I imagine... If the system was empty then it'll continue to be confused !!

If you left the battery connected then the ECU/DMA will have posted a sh1t load of fault codes.

The relay is on the left side of engine bay near the power distribution if that helps... But get the system filled n bled before you condemn anything at this stage HTH ;)

Yes, the first thing I did was disconnect the battery before comencing the job.

I will bleed the brakes up in the morning and try it again.

cheers.

Ok, bled the brakes, pedal solid, but abs pump still running continuously. Took the pannel off were the relays are on nsf in the engine bay, removed each relay in turn, to no avail. The pump still runs constantly.

So where the heck is the ABS pump relay?

Was told by my local main dealer up home that the pump does not need coding, now been told by FAB and other BMW specialist that it needs to be "aligned" to allow a specific bleeding proceedure.

I am now at a loss as I need to go home tomorrow. The only thing positive is that I know this abs pump works as you can hear it!!!!!

Hope someone can help, the car is in St Austell, Cornwall if anyone reading this is local and could help.

John. :(

Have now managed to speak to a BMW mechanic at my local maindealer. As the car is a 51 plate, there is no ABS relay, all the controls are apparentley built into the control unit on the back of the abs pump. So the plot thickens still further :(

Has to be a fault elsewhere... The thing that worries me is that it has power even with keys out !!!

Swapped over the ecu's and with the old ecu mated to the "new" pump, it stops running, new ecu mated to old pump and it runs, so I am hoping, (famous last words) that once the codes are cleared again, that will sort it as the original fault was faulty pressure sensor in the hydraulic unit.

Either way it's outa my hands now as I have to go home tomorrow. So everything crossed please everyone.

So you swapped both at first?

Yes, just swapped the entire unit.