Prob a fuse. Does the interior light work? When i was trying to sort my fuel gauge i blew the fuse maybe 5 times and the indicators and interior light stopped working too.
If it is that change it, if it blows again then there is a problem somewhere in the circuit.
The interior light should be on a different fuse to the indicators / fuel gauge. If the wipers and brake lights have also failed then it will be the ignition circuit fuse. Check the fuse wire and if that is ok try moving the fuse slightly to get a better contact. Fuses do sometimes fail but if the replacement fails then you have a short circuit in whichever component is switched on. Switch everything off when you replace the fuse and switch each item listed above on one at a time to check
I just had the same problem. It turned out that the fuse and fuse holder surfaces were dirty. Polished em up a bit with very fine abrasive seems to have sorted the problem
Definitely a fuse - unless the 'new' harness has some faulty connections. Clean - and spray with WD40. Replace fuse if it has blown - maybe it wasn't high enough rating?