'90 Cummins speedo

[The Other Ross]

Yep,the speedometer on the one ton does not work,odometer as well.Took the bulkhead connector apart cleaned and dielectric greased it ,no help.It really didn't look like it needed it anyway.Anyone know how to trouble shoot these?

[KRB64]

Not sure if I can be much help or not. I think the '90 is different from the '92 but in my odo there is some little plastic gears that break, like the size of a pencil eraser. You can buy new ones and replace if yours is the same. The speedo is a seperate issue and again I think a '90 is different. Go to Diesel Truck Resource, 1st Gen page and there will be a sticky or two on it.

[MoparFreak69]

Since they both arent working I would think it is more than likely a cable/drive gear problem as opposed to a internal speedo issue. Usually on those things they get sticky and the odo likes to add miles like you are driving warp speed but the speedo is still such a tried and true design that there really isnt anything to go wrong with it except have it gum up on you. When my dad bought a 90 3/4ton back in '94 it had the odo problem I described above. You drove a mile and it said you went almost 100. The speedo didnt seem to be affected though. The dealer we bought it from replaced the speedo and never another problem with it from then on, its got 325K+ miles on it now and still going. Oh yeah, the truck too!

[rrfarm4ever]

Not sure if I can be much help or not. I think the '90 is different from the '92 but in my odo there is some little plastic gears that break, like the size of a pencil eraser. You can buy new ones and replace if yours is the same. The speedo is a seperate issue and again I think a '90 is different. Go to Diesel Truck Resource, 1st Gen page and there will be a sticky or two on it.

Hey, I'm not sure if I'm doing this right but I have a 92 dodge and the plastic gears are broke in mine.. I got on the Diesel Truck Resource but I couldn't find the sticky on it.. was wondering if you could direct me a little more.. thanks so much R.F.

[KRB64]

Wish I could but Hughsnet (my server) won't let me access that site anymore for some reason.

By memory. If you go to the 1st gen forum, then there are several stickys. Seems like one says "technical" or something like that. Then you have to scroll down through the various categories. Its there somewhere.

Thats as good as I can do until I get on another server at work or something.

[DODGEBOYS]

it gonna be the speed sensor on the tail shaft of the tranny[2wd] or the t-case [4x4]

[The Other Ross]

it gonna be the speed sensor on the tail shaft of the tranny[2wd] or the t-case [4x4]

Where's the best source and how much?