Hey guys, the speedometer on my 88 b150 is not working. I'm not exactly a car expert so I just do some processes of elimination with my limited knowledge. I removed the instrument panel and disconnected the speedo. I can turn it by hand. I discconnected the cable that connects to the speedo from the from the other end (it screws into some kind of housing with a second cable attached to it and an electronic 2 wire harness plugged into the same housing) and was able to turn the cable with my fingers which then moved the speedo. So I figure the problem is from this little housing on back. That second cable comes out of the housing into a coupling and then disappears under the firewall (assuming its going back to the tranny). I also disconnected that second cable and that one i could NOT turn by hand. Sorry for the novel, but I could definitely use your help. Thank you.

 

That plastic coupler with the 2 wires is the vehicle speed sensor. The over drive will not engage without this being fed info from the spinning speedo cable.

The cable that does disappear under the firewall does go into the transmission on the drivers side. Either the cable has snapped within the sheathing, or the cog/ gear/sprocket which it is attached to is stripped. A heavily frayed cable will cause the cog to strip, so replace both if that is what you find. The cable should pull easily out the speed sensor end if it is not frayed.

I believe to remove the cog, you might lose some tranny fluid. I have never had to do it(1989 b250), although I have removed and lubed the cables from the sheathes.

Good luck, let us know what you find.

 

Thank you so much. I removed the cable from the tranny and it was badly frayed. So I took off the cable entirely but the cables going in and out of that coupler wont come out. I can loosen their connections entirely but the cables wont pull out. Is tha coupler a part of the new speedo cable?

 

AFAIK, the speed sensor/ coupler is not sold with a new speedo cable. It is sold separately for around 43$.

The square drives on my speedo cable always separate from their square sockets on my VSS very easily, and sometimes it is hard to get the bottom cable aligned with the VSS.

 

I guess maybe we're talking about 2 different things here. from what you've said, it sounds to me like the VSS is the housing attached to the frame at the front of the hood right above the grille and radiator. The one that has the 2 cables going into it. Those come loose and detach very easily. I am talking aboout the "coupler" that the bottom cable plugs into BEFORE it disappears under the engine and continues to the tranny. So it looks like this: cable coming from speedometer into top of vss, cable coming out of bottom of vss into "mystery coupler", cable coming out of "mystery coupler going to tranny. This "coupler" has an electronic 2 wire harness plugged into it also. The vss also has a 2 wire harness pllugged into it. It is this "coupler" that the front(from vss) and back(to tranny) cables will not detach from. That is why I wondered what this coupler is, and is it sold separately from the long tranny cable.

 

This is the VSS. On mine it is inline with the speedo cable.

http://contentinfo.autozone.com/znet...SU334/image/8/

That other thing you mention I think is for the cruise control. The cables to that led to and from the gas pedal, throttle linkage

 

Yes! That is the "mystery coupler"! lol. Thank you. That is the thing that the cables won't detach from. Maybe I'm not pulling hard enough or something.

 

Here is a picture of the inside of my VSS. This was the first time I opened mine, and I saw that it had been opened once before, by an Aamco in Florida, who charged me for a New one. Maybe this will help you decide how much force to use to separate the cables.