Hi all - I am a new dodge owner and have a few rookie questions:
- 1990 D250 HD 4x4, automatic w/OD. Only 65k original miles, driven in town only. No highway miles or towing.

1) The OD button does not light up, nor does it appear to engage/disengage while driving. Is this common? I think it may be stuck "in" OD, because it stays in higher (3rd?) gear while at highway speeds. Computer issue? Or tranny?
2) Perhaps this is related: it responds well when accelerating from a stop. But once rolling, it does not want to downshift or add power to climb. Even a little hill in town, and the truck seems to lose guts. Any common known problems with these trucks? Any suggestions?
3) I know I can search for this, but which type of AT fluid do these take?

The truck was impeccably maintained, but it does need new plugs. Beyond that, I have no major fixes unless someone here has suggestions. Thanks for reading and helping!

 

Check all your fuses, The switch should have power. When the OD is off the led should be lit. Seem the switch doesn't have power. The OD engages around 45 mph.
ATF+3 originally but it was superseded buy ATF+4

 

Thanks! I will look into it this weekend

 

nice truck!

 

sounds like it could be lock/unlock selenoid on the transmission. Those trucks in that year range had that on transmissions with overdrive. Sounds like the same issue. Run a diagnostics check to see what codes you're getting. Code 37 is for that selenoid. You can do this by turning the key on off on off on. (don't try to start it). Then count how many times the check engine light flashes.

 

.best to kick down linkage from TBI to trans . very possibly out of adjustment .