I have had the break and ABS dash lights on a few years,I can never find the issue,no codes and I don't have a code reader that speaks to the abs module. I seen someone say the hydrobooster could be the issue if it has a leak. I have never seen the break fluid leaking. But I thought to check the power steering,it is very low and after I put the cap back on my break peddle was pretty stiff and not as soft as it was. I will top it up and see if that was the issue or if the power steering is getting low again then I assume the problem may be the hydrobooster.
Do these take ATF + 4 in the power steering. A 2004 Dodge Ram 3500 diesel 6cyl 4x4 quad cab.

 

Yes, atf4 fluid in the ps system. There is an oring on the bottom of the ps pump that can leak & cause fluid loss, you can see it from underneath.