Rapid flashing indicators

Hi

Defender 300tdi nearside indicators intermittent rapid flashing. Checked bulbs all okay could this be an earth problem and if so where should I look for an earth connection. Some have said rear offside behind wheel arch. Looking underneath wires seem to be located running along top of rear crossmember. Wires terminate in this corner and are concealed by a cover with strange fixing studs How do I get to remove to access the fixings.
Your thoughts would be appreciated

The indicators use a relay to flash which is governed by the resistance of the bulbs. Typically if 1 bulb isn't working the relay will speed up.
Usually the wires that run to the rear of the car terminate in the 'triangle' cover which is inside the rear tub on the offside, just insoide the rear door. The wires run from here across the rear X-member to the other side and up into another 'triangle'.
The rear lamp earths are inside these covers.
Sometimes you need 2 people to get the offside cover off as they have to hold the bolt whilst you undo the nut on the inside..