Abs light stays on and a yellow triangle warnng light

The yellow exclamation point close to the center of the odometer looks like an exclamation point surrounded by parentheses. This light means you should check your tire pressure. Once you have checked the air in the tires and remedied any issues, push the "Set" button on the dashboard. The light should disappear.

traction control is norml the warning triangle.
Traction Control Systems use wheel speed sensors to detect whether there is any slippage occuring between the tire and the road. When these wheel speed sensors get dirty or damaged they can stop working; this prohibits the traction control module from knowing when to enable the system.
clean the sensors and the cogs on all wheels. sometimes can be this.
if dont work check the wiring on the connection it could be loose or corroded ie giving a bad signal.
uselly if the signal is out of range the abs light will also be on as its out of its safe range.
while driving if the speedo jumps there is a bad connection this can be in a number off items that rely on a speed signal. it can also take around 10 to 20 starts and stops of the engine to remove code when the system is fixed. only code reader can check if the code is active or not. and be reset but if its fixed abs will not light up. as abs relies on the signal at all times even when one signal is down it tries to compensate. eather the front or rear wheels.

I think you mean the yellow circle with the triangle and the exclaimstion point? ... That would be a service light. If it says ABS in the center (orange warning light ln the right, not left) then your brake system needs inspected or serviced.

Just a systems check. If it stays on after the truck starts, take it to the dealer or a repair shop.

You know, you could always read the owner\'s manual.

items come to mind Low oil in the m/ resevoir and abs not working . Check for fault codes and have the abs checked out. You may have a blown stop light as well.

Whenever this warning light or any other stays on in the dash it is indicating that the systems control module (or the system sensor in the case of lights like low oil pressure, door open indicators etc.) has detected a fault, it then disables the system (this applies to ABS,TCS, TCM, SRS and BCM faults and others) as long as the light is on. You must now have the dealer hook up a special electronic diagnostic tool and "scan" the system for the fault code that is stored for the problem(s)

Legend of Abbreviations. ABS Antilock brake system.TCS Traction control system, TCM Transmission control module, SRS Supplemental restraint system, BCM Body control module

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.

Thank you for using Fixya, and have a nice day.

dealer only ,ABS -- encrypted software so you cannot read the fault

chek power steering reservoir

Ok, check the brake fluid level for a start. This could mean a few things. Your brake pads might be worn down, which would bring a yellow warning light on(triangle), at the same time with the pads being low it will have displaced the fluid, making the level low, this would be a red light on. Now because of this the body control module has detected these faults, will have turned the abs off, hence the abs light.
If brake fluid is low, this could confirm my theory.
If its low, top up with dot 5 brake fluid and take to garage to have new pads fitted.

TL