I have a '93 CTD with the A518 tranny and have seemed to have lost overdrive. It was working fine when I first pushed it but when i needed it on it never shifted up. I checked all the connections on the tranny and all wires were connected, I looked behind the dash to see if the switch had come unplugged, but it was fine. I also checked the transmission fluid and that was fine also. And there were no blown fuses. Im stumped.

 

Sounds like a bad throttle position sensor. By the way, which dump body kit are you running and how do you like it?

 

Ok, ill look into it....Its a Rugby, im not sure what model b/c it was on there before i bought it. works good for me...