Auto Trans won't always shift into Overdrive? 1992 D250 360

[Fred Average]

Anyone else have this issue?

Happened once before,then it kicked in/shifted and speedometer also started working which was not working.

Now this AM when I came out to leave for work,weeks later after the above incident,it happened again.

Tried turning the engine on and off/restarting and also turning the overdrive button on and off,didn't help.
Also the speedometer stopped working at the same time,are they related?

Thanks all for any help

[Fred Average]

Looks like it's the VSS (Vehicle Speed Sensor) is the culprit
as per other posts here.

The part # is 4638763 for a 1992 D250,2WD,360V8,Auto OD trans.

And no longer available.


Anyone else have to replace this unit and have found a quality source or stash?


Thank You....

[Fred Average]

Well,at this point it seems it I$ the VSS unit on the trans.

MOPAR doesn't sell it any longer...

So the best one available is from NAPA.

Part # : VSS100 made by Echlin.

NAPA offers 2 ,Don't buy the cheaper one,get the abovementioned unit!

[dazedandconfused]

Did this solve your issues?

[Fred Average]

Hi,the original unit started "working" again,it seems to be affected by lack of use(vehicle isn't used for a few days or temperature-cold mornings below 45 degrees).When it again fails,I will install the new unit & keep all advised.

[Fred Average]

Hi all,yes the new VSS unit has corrected the issue.

It would appear the next thing to do to eliminate some sporadic workings of electrical components is to add heavier gauge and more of them grounds thurout the truck.

Anyone eles had similar issues?

Thanks