I have a 1993 w250 cummins with a 518 trans. My speedo stopped working yesterday, So of course i lost overdrive. I checked the speed sensor at the tail shaft of the transfere case. Put a drill on speed sensor and check the two contacts with a ohm meter, looks to have singal but ohms are not constant at a constant speed of drill. Also checked gear reduction unit attacked between speed sensor and transfere case, that seems to be in good shape. The funny thing is my 4x4 light is also always on now since the speedo stopped working. Does any one have my next step???? I can buy the speed sensor at parts store for $30.00 but not sure thats the problem, becave the speedo in cab does not move at all , but have a singal from speed sensor. HELP. Does any one know if the 4x4 light and the speedo problem are related the 4x4 switch is only 4 months old, dont think there is a problem with that switch.

 

I'm not sayin it is related but I have a 4x4 Nissan hardbody that When it's speedo went out the 4x4 light came on on the dash and won't go off either so it's a possibility.


MAHLE_12V

 

i just had the trans out of mine and had an intermitant problem with the four wheel light , while the trans was out i noticed the harness that has the od, speed sensor, and transfer case wires in it , which is just taped from the factory , was rubbed thru at the harness clamp ontop of the transmission. could this be your problem?

 

Well I got a 91 350 4x4 and my speedo doesnt work either its got a new sensor, and wires are good and gauge is getting power but gauge doesnt move nor does the miles, but my 4x4 light doesnt stay on? and it's a 91 1/2 so its eletrical speed sensor btw

Any help on that????

 

yea i will agree with flying c rodeo cause i have the same year and i have power to the dash but i have no miles working and no speedometer working so i go off mt rpms

 

I believe that the computer is the problem... onlything left that i can not check. Checked everything else. wiring related. Swaped out the speedo unit , that was not the problem,All the wires that start at fuse block seems to make there way to the driver side fender. Called parts store and distrubutor is out of stock on the ECMs. The problem with 4x4 light is the switch at the transfere case, Any other input would be great. Thanks todd

 

what year is your truck mine is a 91 and my buddy has a 93 and beleive it or not there is a lot of difference int the two it amazez me how mush they change in just a few years

 

My truck is a 1993 w250 4x4 automatic

 

well my buddy has a 93 as well and he ahad the same issue but some how fixed it ill ask him what he did to fixe the onl difference is he and i have 5 speed manuels instead of the autos but my speedometer dont work either and his didnt but he did fix it so i will find out for you

 

well there is a diff between a 91 and a 93.... but if im wrong correct me please, the 89-91 are the same then they changed alot of stuff in the 91.5-93 with intercooled cummins and alot more electronical stuff. I prefer the 91.5-93 myself. but the earlier ones are easier to work on i think for all the lil stuff