Ceck all of the ground wires and connections first! An increase in current draw ( a brake light or a turn signal ect.) can cause a poor ground to fail and the indicator to light. Any green or rust around the connectors replace them. Poor grounds and intermittant tail light sockets on our 85 245 dl recently cost us $339 in fines and $125 for a tow. The !@#$#@! county police here in Indiana do not have a sense of humor. I finally replaced the stock sockets with aftermarket sockets, complete with new ground wires.