Fixed a brand new ABS Assy 2005 but experience grinding noise and can't stop but things begin to work ok once the ABS light comes on. What might be the problem and possible solution.

 

did you fill the diff with gear oil?
2005 4Runner or Taco?

 

If you've done stuff to the ABS system, like opening up the lines to the module, you might have air in the lines. Should be a way to bleed it from the module, but my guess only. If the assembly contains a fluid reservoir, it likely is low on brake fluid and needs to be refilled as well. The grinding noise is likely just the ABS motor running. It's more like a low-pitched buzzing noise. ABS light comes on, it probably put itself on standby until you pull the codes from the diagnostic. Your main braking system works, but you will not have ABS to help you if the wheels spin out (dangerous during rainy/snowy weather).