Check all ground wires first! If there is any green or rust around the connections replace them. The increased current draw on the system ( brake lights or a turn signal ect.) can cause a poor ground to fail and the indicator to light. Poor groundsand defective 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 finaly cut the old stock sockets out and rewired aftermarket sockets in, complete with new grounds.