Maybe the VSS is dead internally?

 

Well I would think that if the sensor was dead that the speedometer wouldn't work at all. I don't know I might pull my cluster out satuday which is my next day off delivering hot pizzas lol.

 

Okay lets try again here is my 92 F350

 

If you look closely at the hood, Rear fenders and around the drivers rear door handle you will see where the clearcoat is peeling and paint flaking. 3/4 of the roof now has primer since the paint deteriorated and rust was becoming apparent other than that not a spec of rust on or under the truck.

 

That ain't no ext cab, tis a fullsize crew-cab beast, and a darn good looking one at that! By the way, is that a recessed step that I see in the bed side slightly forward of the rear fender and a bit towards the bottom?

 

Yeah thats a recessed step alright. Don't know if the PO owner or the owner before him did it. Its only got the one though. Any other thoughts on my speedo problem.

 

Tell ya truth, no idea on the speedo - I'd pull the diff cover off and look at the tone ring to make sure it ain't missing teeth or is bent or something (yeah, it's a very long shot, but itisa shot), I'd also change the oil in the axle, I'm having thoughts on clutch wear material from the limited-slip differential (if you have one) may be getting caught on the tone ring and messing up the VSS reading. Then if problem is still there I'd probably put a new VSS in the axle and see if that helps. Next on the list would be a gauge cluster from a junkyard truck...

 

Is there any way for a dealer to test the cluster computer? I know this truck is still all mechanical, but I think it should still be OBD1 compliant. There may be a code port on it that might be able to help.

This is also a long shot, but if there is still a PCM to manage the speedometer and related sensors, maybe there are some codes stored.

 

without pulling the cover is there anything on the I.D tag on the differential to tell me if its limited slip? Im pretty sure it isn't because this was the F350 Custom so from factory it had no a/c, no cruise, no pwr door locks or windows, so an extra like a LS differential im pretty sure it wouldn't have. As far as the computer the dealer said they couldn't its was probably my cluster (which is what i have suspected from the start). I think the garage I used to work for still has a cluster that is good out of I think late 93 early 94. I'm pretty sure it should work. I'll see If I can borrow it to see if the problem dissapears. Until then if you have any other suggestions feel free to let me know.

 

You might try removing the cluster plug and then reinstalling it.

I have seen that cure dash gauge problems before.

 

Yeps, give the "unplug -> plug back in" thing with the cluster harness, may just fix it. As for the differential ID, there should be a tag attached to the diff cover with one of the bolts, and also if you still have the build label on the driver's door jamb (near the striker bolt) there is a box on it that will tell you the axle code.

 

What on the tag should I look for. The only thing I have been taught to interpret was the gear ratio. which is 4.10 on this truck.