NO speedo, NO overdrive

[tobaccogrower]

noticed the otherday somthing hanging from under my truck. it was what i think is my speedo sending unit. it's right where the driveshaft starts on the transfer case.



i screwed it back in tight but now i have no speedo and truck wont shift into overdrive. it looks liike a mini gear drive. also checked the connector.



whats the next step to getting everything working again? luckly i dont have to drive more then half mile to work!

 

[JDancoe]

The "mini gear drive" is a ratio adapter. Take it off and remove the speedo sensor, the part with the electric plug, and spin the drive key on the trans end and see if the top end spins. the one on mine failed-the gears inside ate themselves up. You also can take it apart with a screwdriver and inspect it. Also check the square drive on the sensor. Mine quit (wore out the tip of the square drive) when I was on a trip. I took the rubber seal out to let it set deeper into the ratio adapter, and it worked until I got home and could replace it. Hope this helps, Jack Dancoe

 

[tobaccogrower]

i think the square drive snapped off and a piece is still stuck in the transfer case. it looks like where the speedo sender mates with the transfer case will unbolt. it has a 24mm nut built into it. can i unscrew it and take out the broken piece?

 

[JDancoe]

Yes, it just unscrews. You should be able to remove the broken part without too much difficulty. If the drive key for the adapter is broken you may need to buy a replacement ratio adapter. If your dealer doesn't have one, find a shop that repairs & calibrates speedometers. The adapters are pretty generic, and most good speedo shops will have them, and/or will have the parts to build you one. They will even be able to change the ratio if you need the speedo re-calibrated because of tire changes, rear axle ratio changes, etc.
Good luck Jack Dancoe