Had the same issues with the 3 amigos now for weeks(2007 FR2), doesn't show a fault most of the time, occasionally the abs module comes up.and the rear right sensor (changed)
lights actually go off by themselves ??? and don't return for a day or 2.
To put you in the picture I have changed the rear hydraulic flexi hoses as one was leaking a bit and done a fluid change, also the right rear shocker as was scrubbing front nearside tyre badly.Serviced the car while I was at it, all levels looked good on the first inspection.
Now as it happens my steering started squealing and the 3 amigos immediately came on !!!!!, read all the forum posts on this issue so obtained new oil and decided on changing aux drive belt while I was at it, dropped the false floor and it was full of oil (not helped by the sound proofing) ,
close inspection showed a small leak around the lower steering column power steering pipes, on checking my reservoir it looked just above min,????
Closer inspection of this showed me it was a tide mark! of where my fluid once was! and has duped me into thinking it was at the correct level.
power steering pipe repaired, fluid topped up and bled, the problem of squealing has now gone.
Hopefully, the 3 amigos may have gone away also.
Hope this helps others who have the same problems, has had me tearing my hair out.