2002 isuzu r0deo sport 4 cyl. manual trans, 2WD; no cruise control, no alarm; wprers have 1 intermittent speed; problem is headlights were on when I went out to vehicle; the headlight switch was not on; there was a buzzing sound coming from the headlight relay in engine compartment; removed relay and buzzing stopped; installed new relay and same problem; I replaced headlight switch, but still have same problem/symptoms. Can you offer any help, please; vehicle is in very good condition otherwise