UK Explorer warning light

Hi, Ford UK dont want to know Explorers. So I'll ask the people who are sure to know. 97 Explorer 4liter. 125,000 miles. Just ordered a prelube kit from
California. Stop it from self destruct. Usually over here about 80-100,000 timing chain destroys hydraulic adjuster, metal bits kill the oil pump and the engine. Engines are difficult to find and pricey in UK.
Overdrive warning light has started flashing today. Wont hold 5th gear? No noises. No overheating . No shortage of any fluids or oils. Any ideas out there where to look first.
thanks Ian Lowrie

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.