The first thing you need to do is get into a shop or auto parts store and get the codes read from the trans. This will give you a starting point. If your lucky it is something simple like the speed sensor otherwise you may be looking at a trans rebuild or replacement. You definitely want to look into this before your stranded far from home. Having said that i will say that on my 99 Windstar the OD light has been blinking for over a year and i can see a difference in rpm's when it does. One day i may go buy a speed sensor to see if that solves the issue.
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1998 EB Expedition 4X4 200,000+, 1999 Windstar 200,000+ (Needs Head Gasket), 2008 Chev Colorado (Company Truck, Really sucks but it's free)
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