Abs light on what is code U1900

SOURCE: 2003 Ranger FX-II ABS light on

This isn't hard to do at all really and should be easy to procure the part from the local parts store. There is only one little screw holding it in

1. Raise and support vehicle.
2. 
   NOTE: Clean off dirt and foreign material that may have collected around the rear anti-lock brake sensor before removal. Remove the rear anti-lock brake sensor.

1. NOTE: Thoroughly clean the mounting surface. NOTE: Inspect the anti-lock brake sensor O-ring for damage; lightly lubricate the O-ring with axle lubricant. To install, reverse the removal procedure

SOURCE: abs light wont go out

When u power up the vehicle ABS does a self test(light stays on a few seconds then cuts off) and if it see's a problem will shut off and illuminate the ABS lamp. It will also do a second test on iself when you reach a speed of around 12-15 mph,it will run the pump for a few seconds to check pressure and look at the speed sensors,if it see a problem here it will again shut down and illuminate the ABS light.
Now if the red brake lamp is on then it will shut down because it thinks you have a hydraulic concern and will not try and run ABS if this is the case.
If red brake lamp is on most likely if you have good brakes it is a problem with the float sensor in the master cylinder reservior,maybe its bad or just stuck,or just low on fluid.

SOURCE: 1997 ford f-150 flashing abs light (flashes 15

Does your speedometer work ok? There is a sensor on top of your rear differential that provides a signal to both the abs and the computer(speedometer uses the signal from the computer) This sensor goes out pretty common.

SOURCE: abs rear light stays on

The sensor is located I believe on the differential housing,could be faulty or corroded

SOURCE: abs light stays on!

unhook the battery, the light should go off...if the light comes back on then you may need to get your abs checked