Speedometer Reading WAY TOO HIGH!!! Just installed new sensor

[FSecosky]

Okay, so I just got this truck and... the speedo/odo/cruise was not working, so I went up under there to check the VSS on the back of the transmission. I saw a 2 wire harness dangling down, and a hole with threads, and nothing attached. So I figured for some reason the VSS was not present anymore. I went down to AutoZone and they had one in stock. I installed it, and hooked up the harness, and the speedo reads now, and the odo, but it is WAY TOO HIGH. It almost reads about 2X as high as I am really going. Now, maybe AutoZone gave me the wrong sensor? But, the real question is, why was the VSS missing off the transmission in the beginning? Carfax shows the last mileage recording was 3-4 years ago at the same mileage it is now... So, was there another problem that preceded the removal of the VSS and that is why it was missing? What could be the problem here?



One note: The sensor I got from autozone came with a small harness, male to the sensor, and female to attach to the truck harness. But, the truck just had a male connector dangling from its harness by the transmission. So, I did not even use the autozone harness and just connected the original truck harness to the VSS directly. Then, the clip on the truck harness broke, so I spliced the new autozone connector onto the truck wires and installed it with the new harness that way.



You think maybe the truck has a 4. 10 (or shorter) in it now, and maybe it had something much much taller in it years ago??? I do know it is an open diff, as I was spinning in some rocks today.



1993 d250 5sp reg cab

 

[FSecosky]

Well, I think I have figured out something from the old posts already. I did not put any kind of 'gear reducer' on before just screwing on the VSS. I guess I need this. Is this a part that is the same across all the trucks, or do I need to know my gearing of the rear end?



Also, when the VSS is off the transmission, fluid can leak out? and dirt can get in? Wow, there is NO telling how long that has been off, I gotta drain that fluid ASAP and overfill it quick so that no more damage is done, I hope this transmission is okay!

 

[EZeis]

Your correct, you're missing your ratio adapter. They should be different from truck to truck. The VSS is the same for all. The ratio adapter was used to allow for different tires and rear axle ratios. Most likely you'll have to see the dealer to get the correct one.



The port on the trans is sealed, so you wouldn't of lost fluid or got dirt in the trans unless the seal on the drive is bad. You'll probably want to clean it real good with brake clean or such and keep an eye on it for leaks.



While greasing my truck a few months back, I happen to look up at the ratio adapter/VSS and seen that the ratio adapter had a grease zerk. I was like cool. When I tried to grease it, the whole works was loose and about to fall of the trans! So I wouldn't be surprised if yours fell off the trans and hung there till the wire connector let go.



Rear axle ratio would be listed on the underside of the hood on the option sticker. If you think someone changed the gears, better count them. The dealer is going to want to know gear ratio and tire size for the correct ratio adapter. Note, OE tire size was LT235/85R16.





Earl

 

[FSecosky]

Thanks for that insight. The truck is not within reach of me right now, so I am going to try to go to the dealer today and pick up an adapter, just guess that the rear end might be 3. 54, that sounds like a common ratio, and it does have the OE tires. I am trying to get the truck ready for a long trip this saturday, so I just want to try and get this taken care of asap. Thanks a million!



~Forrest Secosky

'93 d250