1995 Explorer 4.0 2wd 240k on it. I have only had the truck for a couple months. When I first bought it, it had a really bad miss which turned out to be a bad coil, however I didn't notice ant tranny problems. After I got the miss fixed I started having some tranny trouble, It will only slip in overdrive and only when it is warm. It does throw code 648 4th gear incorrect ratio. I have changed the trans fluid and filter (nothing in the pan and fluid was a little dark but not awful), adjusted the bands, tried lucas and seafoam to no avail. If I clear the code it will shift fine until it is warm and I have to step on it, if I am just cruising no hills, no slow people, then it is fine. If I disengage overdrive before it starts flashing it will run fine other than it too high of rpm's. So my question does this sound like I am due for an overdrive band(if so full rebuild) or does it sound like maybe a servo or valve body?

Any help would be greatly appreciated.

Thanks Jason

 

Check your tires for size and wear, if they are mismatched or if one or more is worn more than 1/4" it could cause a code of that type. Gear Ratio.
Trans slippage is a whole 'nother problem.

 

Just in case anyone else has this problem, it was the servos both were bad!

 

Thanks for the information, I'll store it in my memory bank.
Glad you found the problem and fixed it. Both servos going bad at the same time seems unusual. do you think it was wear or an error in the reassembly when you rebuilt it? In any case "Good Job" and I'm glad you're up and running now.

 

I dont think it has ever been rebuilt which means there is 240k on the original servos and I dont think they just went bad I think they have been going bad. I was just lucky enough to be the one to replace them.