93 Ford Escort Wagon Speedometer doesn't work?

[Irb]

Hey there, I just got a 93 Ford Escort a couple months ago for my first car. So I'm finally driving it now, and I noticed that it doesn't drive as fast as when I'm driving my mom's car. I'm supposedly driving at the same speed, but it just doesn't feel right. How would I go about testing or fixing this? Any help is much appreciated.

[Escort_Phan]

I had several issues at once (including yours). Here were my symptoms:

1. Poor idle (hi-low-hi again)
2. Cooling fan wouldn't auto turn on (had to hook up a switch inside)
3. Cruise wouldn't work
4. Speedometer was all over the place, then quit working

Prior to fixing my speedometer, I was using a GPS to tell how fast I was going (got sick of the batteries). I also emoved the "dark stuff" from my cooling system. Turns out that was Ford stop leak (there was even a service bulletin about its color). Well the stop leak was doing its job (till I flushed the system). Wound up doing the transmission/clutch and some other things a bit more relevant to your question.

1. Idle Motor
2. VSS aka speed sender (see below)
3. Coolant Temp. Sensor (tells computer how hot)
4. O2 sensor (replace it, it helps performance and mileage)

I also replaced a Freeze plug (had small pit hole in it probably).
Fortunately I also had a slipping clutch so the work removing the trans. wasn't just for a $2 piece of metal

Enough back story and on to your question..

The whole point behind me replacing the transmission (for your answer) was I discovered the piece that the speedo cable plugged into. I've seen others call it a VSS but I'm not 100% on it's name. It has 2 purposes in one. The cable (mechanical) tells the dashboard gauge how fast you're going. Then there's a 2 (or three) wire connector. That tells the computer how fast you are going. In my case both were broken internally in the VSS. I replaced it and had both cruise and a dashboard indication of how fast I was going. (also discovered that if dash says I'm doing 35, GPS said 32~33). When you replace that part pay attention to the color of the plastic gear that the tranny spins. There's at least two color possibilities, maybe three or more. I think it has to do with how many teeth are on the gear and thus how fast the car (and dash gauge) think you are traveling.

The next thing I discovered was that there are two water temp sensors. (unlike the speed thing with two in one, there are two different temp sensors). My dash one was working, so I replaced the one that told the computer how hot the coolant was. (My radiator fan worked at that point! It now comes on somewhere between M and A in "NORMAL" however it runs much cooler normally)

The last thing I did was to replace the "idle motor". That did wonders for the hi-low-hi idle I had (between 500 and 1200 rpms). Nice and smooth.

So I had cruise, cooling fan back. And 4 more MPGs!

So you probably want to focus on the VSS (again not 100% on the name). It's at the top of the transmission (if your looking under the hood from the front bumper). It's to the left of of the battery, just to the back of it. (just look down near your master cylinder).
The speedo cable is held in by a paper clip thick clip. (pain to remove without bending it out of shape).
The VSS is held to the transmission with a U sort of metal clip and the clip is bolted to the trans.
And do yourself a favor and get a L-O-N-G socket extension to take out the bolt holding the U clip on. (chain several together if you have to).
Don't pry to much on that piece (VSS) it can break. I had to rotate it (Slightly) a few degrees back and forth using the U clip (unbolted) to free it up some and it finally came out.
That piece is probably the culprit, but you can try to verify by spinning the cable (once undone from the VSS) and seeing if the gauge indicates speed. (Spin it both directions to make sure you aren't "in reverse") But don't go too nuts as you don't want to wear out the cable. This step might require a second person to stare at the instrument cluster and say that it's indicating something above zero.
My cable (to the gauge) was worn also, so I replaced that too.
It's a little tricky undoing it from the back of the instrument cluster.
But that should take care of your speed indication problem (also check the wires going to that, to make sure they aren't broken or the computer won't know how fast your going).


But also replace you're oxygen (O2) sensor if you've never done it. It will perform nicer.