ABS Pump Rewire



This is how I rewired my ABS pump in my 1996 BMW 328i


Remove the pump by taking off the 5 or 6 fluid lines, disconnecting the electrical connector, and removing that one nut at the front end of the pump assembly.  Takes about 10 minutes to remove.  It might be easier if you remove any little bits that are hovering above the pump assembly.  I took off the MAF and air tube and moved some other stuff around to make it easier.


Once it is off, take it to your bench and CAREFULLY clamp it in a vise or otherwise position it in a stable manner so that you can remove the plate on the bottom.  There are 6 torx headed bolts that you remove to get to this area of the pump.

This is what it looks like at first:

Note all the corroded flexi-cable.


Here is what it looks like after you carefully desolder and remove all the flexicable and rewire it:

Here is a wiring diagram I drew up.

All the solenoids share a common contact, and these are all tied back to pins 2 and 7 on the connector.  Notice that pins 2 and 7 on the connector are also common.  I numbered these myself and these numbers mean nothing and do not relate to any numbers you may find on the connector.

I started at the right side of the connector from the perspective that my pictures were taken and numbered it from right to left.  I did this also because the wires come into that connector from the right. 

I have no idea what gauge of wire to use.  I am obsessive, so I went bigger than I am sure you really need to.  To do it over again, I would buy a good grade silicone insulated wire so that you wouldn't have so much trouble melting the insulation during the soldering job.  We used 16 gauge, but I bet 18 gauge would be easier to work with and still meet operating expectations as well.

I bled the brakes normally starting at the farthest wheel and working my way in.  The normal way, having someone pump then hold the brakes while I cracked the nipples.  I went ahead and bled them until the fluid was clear so effectively changing the fluid, but I don't think you HAVE to do it that way.  Lots of people talk about shorting the relay to activate the pump during bleeding, but I didn't do it, and I have used the ABS several times after this repair and it is working fine and I still have normal brake pedal feel and pressure.

My ABS light went right off after we were done bleeding the brakes and started the engine. 

Hope this helps you and good luck in your repair!



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