Diagnosing Trifecta
 

Just a few days ago my "trifecta" came on. All yellow lights, so know it isn't a brake system issue. It did go off a couple of times, but is back on now steady. I did the steering wheel turn from lock to lock to make sure it wasn't the angle sensor. I pulled out my Creator 310 and monitored all 4 wheel speed sensors and I am getting readings at all wheels. I did get the module repaired 1.5 years ago and the system has been perfect. I know there is a tutorial on using a DVM on the wheel speed sensors, but since I am getting out put and it is showing up on my scanner, pretty sure I don't need to do that. May take all wheels off and check connectors as a preventative. And of course I am due for my yearly state inspection-this happens to all of my BMW's. Every freaking time for inspection, something pops up right before they are due!! Any help would be appreciated. Truck is an 01 with 4.4.

Turning the wheels lock to lock won't clear the trifecta if the steering angle sensor is bad. When mine went bad it did just like yours, came on and off a few times then stayed on. I have a Creator and it has a check for the steering angle sensor. Did you check that with yours?

Battery and alternator in good shape I assume.

My 2 cents: My abs module got repaired few months ago, the problem was solved for a couple of weeks, then she started acting up again. My only error in inpa was front left sensor plausibility, but it was brand new (aftermarket) so I thought it wasn't related. Long story short, the module was bad beyond repair, bought another from a donor X5 that was ok and compatible, also I removed the new aftermarket sensor, and put my old oe sensor with a connector broken, I fixed it, and voila! no more issues. Conclusion, abs module repairs are not that reliable and stay away from aftermarket sensors.

Thanks all. Appreciate your input. I did go back with the scanner and found the Steering angle section. There were a couple faults, cleared those and will check if it returned today. A funny thing was discovered yesterday. Happened twice. If I backed up first, the lights would go out within 50ft of driving forward. I think I will take all wheels off, remove sensors and check wiring and also check connection at module. We have had a lot of rain lately and am wondering if my deteriorating WSS connectors are allowing water in and causing problems. Will keep this updated.

Just because you got the ABS module repaired 1.5 years ago does not mean that it hasn't failed again. I would start at the module since it exhibits all of the classic signs.

Module
 

I sent in my module to Module Masters in Idaho.
They have a 5 year warranty. I was getting trifecta lights without
moving the car. I sent mine in without doing any other diagnosis.
The repair came back that it was indeed at fault.
I haven't finished my cooling system refresh to see if it's fixed.
I'm guessing the module was the culprit.

ABS module, don't waste your money and time replacing other parts. you can have the abs rebuilt (this didn't work for me, wasted $100), or go to a junk yard, pull another abs module and have it program to your car. if you have DIS, you can program is yourself and save yourself $700+ in programming cost.

also wanna add, i drove mine with the trifecta lights for a few months.

I have a 2005 X5 with 4.4, my trifecta lights was caused by a broken transfer case actuator gear (plastic). Not sure if your 2001 is the same, but worth checking. You'll usually hear a clicking sound when you turn the car off (worm gear skipping over broken teeth on plastic gear). Not hard to check, actuator held on side of transfer case with 3 screws and unplug wire, looks like a power window motor. I had 2 Odometer Gears brand gears go bad, but replaced with this $10 Amazon gear and has been working for 3 years https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
The Odometer people were great, gave me a free replacement when the first one went bad, but this Amazon one is working.

No actuator on the transfer case on X5s before about 09/03. The actuator is part of the XDrive system, introduced on the facelift cars.