Daf lf45 warning lights on! ?

Hi there! I am having a problem with my 61 plate daf lf 45, code1: red abs warning, code2: yellow Abs warning, code3: yellow engine warning! When plugged into diagnostics no abs fault was found then it immobilised itself! 10 mins later, no problem at all, on route back to depot faults appeared again then lost speedo and rev counter, PTO will not engage, main earth from engine to chassis looked a bit iffy so has been replaced! Problem still accuring! Checked main fuse behind batteries and is fine! This problem seems to come and go when it wants now, as it is a 24hr recovery vehicle this needs sorted quick!