I just bought my first 740 a few months ago. It's a beauty. It had several flaws (cracked windshield, headliner sag, temp. sending unit, cracked dashboard) but runs great and only has 110,000 miles. I have 2 240s, a 1988 and a 1992. Anyway, I've been working on the 740 little by little and one problem has been the overdrive light comes on. Sometimes when I push the button on the shifter it goes off and sometimes it doesn't. I've removed the switch on the shifter and cleaned the contacts. It will work fine and than not work. I'd like to know how I can determine if the problem is with the switch, the relay, or the solenoit. Thanks in advance.