How do i get the abs/ yellow triangle of I've

I quote some details from BMW's owners...
Symptoms: Dreaded yellow triangle, ABS light, and CEL on. All other functions (speedo, tach, cruise control, trip computer, etc) working.

Procedure: Pull the ABS controller out and disconnect it from the wiring harness. Mine is under a panel to the left of the glove compartment. Remove the wiring backshell so you can get at the wiring connections on the back side of the connecting plug (you need to be able to see the colors of the wires and get a Ohm meter probe on them).

Using a Bentleys Electrical Manual find the connection diagram for the wheel sensors to the ABS Controller. The pin designators will most likely be wrong (they were for mine) BUT the color designators for each of the wires is correct.

Example: Right Rear sensor is connected by two wires, one blue and one blue green.

Connect Ohm meter across these two pins. NOTE: I wound paper clips around the probes to make a very small probe tip which helps. Write down the resistance reading. Mine was 3.08k ohms.

Work through the other 3 wheels and write down the resistance readings. If any of the pairs is open (i.e. infinite resistance) you have a bad connection between the ABS Controller and the wheel sensor. You can then remove the affected wheel, unplug the sensor, short out the pins on the plug (not the wheel sensor part but the chassis wiring part) and if the ohm meter is still reading open you have a broken cable between the wheel sensor and the ABS controller. If the cable is good connect the ohm meter across the wheel sensor itself and if the cable still reads open you have a bad wheel sensor, replace and retest.

Here is what I found. All wheels read 3.08k ohms except the right rear which read 4.4M ohms. This sensor was replaced during my rebuild exercise and it looks like they provided the wrong part. I replaced the part with a dealer item and retested. 3.08k ohms was read with the new part. Reconnected everything and the ABS light went out, the yellow triangle light went out. I used my OBDII computer interface to clear the CEL light and all is well again.

Total testing/repair time: 2hrs and 35 minutes!

Here is my theory. The "older" ABS Controllers (like mine) use sensors with the lower reisitance (3.08k ohm) while the newer Controllers use the higher resistance sensors (4.4M ohm). The part I bought was from a 02 E39! I can return it but I think I will use it to test my 00 528 problems first.

Additionally, I suggest check charging system (alternator/power module/battery) has a defect that a professional BMW technician should look at, Most probably the alternator is toast.

Hope this helps; also keep in mind that your feedback is important and I'll appreciate your time and consideration if you leave some testimonial comment about this answer.

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