Speedometer, odometer do not work?

Hello,

It sounds like the PCM went bad but to be sure lets do a wiring check between the VSS and the PCM. Here is a guide to help us and the engine and transmission wiring diagrams so you can see how ti works and which wires to test. Check all fuses as well.

https://www.2carpros.com/articles/how-to-check-wiring

If the fuses and wiring checks out I would try a used/rebuilt PCM. Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.

Cheers, Ken

Will do, I will let you know the results this weekend.

Please do.

Did a recheck on wires and found the wires to the ABS sensor on the rear differential broke. I fixed them and the ABS light overdrive light both went off but the speedometer works fine until you reach 50 mph then starts bouncing around like crazy. Gas gauge still does not work. Thinking sending unit, needle moves from full to well overfull when I turn the key on transmission still has a pretty firm shift and shutter from time to time on the highway.

Maybe filter fluid change on transmission?

Is the VSS sensor OEM? I would install the old one if not. Cheap sensors can make the needle bounce. It does sound like the fuel level sensor for the fuel gauge issue. To confirm the issue remove the fuel gauge wires and ground it, (yellow and white wire).

I cannot find a yellow and white I have a brown and white and yellow and green. Then an redish orange and thick black. I assume those are fuel pump, the other two wires give no signal on my meter, and gauge does not react when they are grounded.

Oh, put the original VSS back in and all other problems fixed. Speedometer and odometer work fine. ABS light is off and she shifts normal. Thank you for the help. All that is left is gas gauge.

Gas gauge repaired, I bypassed the yellow and green wire and the gauge started working. Every issue I had was faulty wiring.

Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help

Cheers, Ken

My 95 ford was running along fine on a sunday night. It snowed, i did'nt drive it again till Tuesday. Suddenly my Tranny was shifting extremely hard from 1 to 2 and moderately hard from 2to3, My power door locks stopped working, my speedometer stopped working, and my dome light stopped working. Mechanic told me to try speed sensor, bought one, that part may be on my truck but it sure aint on my tranny! Tried replacing ABS sensor. Took my rear diff cover off looking for some sensor that my dads bronco has in there and had been replaced for same probs. dont have one! so my questions are this, Could it be a fuse or rheostat? something in the main power distrubution box? And where in the Heck is my speed sensor located?? Somebody that had the truck before me installed electric fans, poorly, we had to rig a switch for them so maybe he messed up something else? he went through Power ditrb box. also dont know if this makes a difference but the truck is a 95 built 10-94.
any ideas?? please help, layed off mom with 3 kids!!! Really tryin to fix this myself!

the truck ran all right until it snowed, could soem wires have gotten wet and shorted. Check the battery connections and clean if needed. also check the ground wires. some look all right but are not getting a good ground. with everything stopped working after the snow , that what I would think happened, I don't see why the transmission, the door locks, dome light, and speedometer would stop all the same time unless something happened to the electric. Make sure the fuses are good after checking the connections. There should also be a fuse box by the front fender under the hood.

thanks so much! i will check those things. I had already decided it had to be electrical as i noticed more n more things not working... had suspicions of the power distribution box... Now i will also check on wiring! thanx again!

while driving the other day, was going downhill and noticed my speedometer and electronic odometer quit working then tranny down shifted with a jolt, when sped up transmission now shift at 2500 rpm but with a hard jolt , any ideas

The vehicle speed sensor is located on the differential housing in the middle of the third member. Here is a guide to help you see what I am talking about.

Check out the diagrams (Below)

Please let us know what happens.

Cheers

Yep that did the trick I got a new sensor for 34.99 and it fixed the problem thanks for the tip this site is great.

1994 F-150 5.0L 4x4. Speedometer and odometer went out and transmission is knocking when it changes gears (auto). I changed VSS but same problem. I also changed fuse under dash with no luck. Any suggestions? Could it be one of the large fuses under the hood in the connector box?

Check the fuses to make sure, but your first guess is mine too. If the check engine light came on, have the computer scanned to determine if there is a code relating to the trans. If there isn't a light, check to see if there is power to the speedo / odometer. If there is no power, start tracing wires back to the pcm to see if anything is disconnected, corroded, or damaged. You may actually want to start at the VSS to see if there is power there and trace that back. It will save time. There is one other thing you need to check. Under the dash (behind the fuse block) is a module known as the GEM. On many of these model year vehicles, the windshield would leak (not enough for you to see) and get the GEM wet and eventually cause it to short. Check the module for any evidence of water getting to it. One last thing, if you haven't, you may want to try a different VSS. With all the importing of products from other countries, there is a chance you got a bad one. It happens more than one thinks.

When I press on the gas between 1-5 mph the speedometer rises all the way to 80. It goes back down when I brake. Also, where it shows how many miles I have, it blinks 230,000 and error right after the display of miles. How do I fix the speedometer reading?

Good afternoon,

Do you have a scan tool to be able to read what the ECM sees from the speed sensor?

That would be the way to tell if you have a vehicle speed sensor issue or a dash cluster issue.

The sensor sends a signal to the ECM and then the ECM sends that signal to the dash cluster.

Roy

PURPOSE
The Programmable Speedometer/Odometer Module (PSOM) provides a vehicle speed signal input to:
- Powertrain Control Module (PCM)
- Speed Control Servo Amplifier
- Instrument Cluster

The speed signal is used by the PCM to determine transmission shift points and torque converter clutch operation.

OPERATION
The PSOM receives a vehicle speed signal from the Differential Speed Sensor (DSS) on pin 4 DSS input, and pin 5 DSS return. It converts this signal to a standard 8000 pulses-per-mile speed signal output. This output signal is sent to the PCM on pin 3 PSOM (+) and pin 6 PSOM (-).

The PSOM receives two power supply inputs. Pin 1 receives a continuous 12.0 volt input while pin 2 receives a 12.0 volt input only when the ignition switch is in run.

RELATED DIAGNOSTIC TROUBLE CODES

DTC 29/452 PCM detected an error in the PSOM output signal.

The Vehicle Speed Sensor (VSS) is located on the rear axle housing.

i just replaced speed sensor not more than ten minutes ago and the cable is fine too i checked but the speedometer isn't working cause it affects the way the truck shifts (stupid design) is there anything else what can cause it not too work. also my gauge is fine cause while cable was mounted too sensor i spun the little wheel and i saw the needle jump on gauge

I have a 93 Ford and had the same problem. Believe it or not all it is is a burned out fuse. I think it was #8 in the fuse box but can't remember that for sure, it was about a year ago it happened. It makes the shift from 1st to 2nd very rough and the speedometer doesn't work at all. Replace the fuse and it runs like new and the speedometer works again. Hope this helps.

i just replaced speed sensor not more than ten minutes ago and the cable is fine too i checked but the speedometer isn't working cause it affects the way the truck shifts (stupid design) is there anything else what can cause it not too work. also my gauge is fine cause while cable was mounted too sensor i spun the little wheel and i saw the needle jump on gauge[/quote]

I am trying to fix up my F150 and would like to know if a the instument cluster can have have a speedometer cable and an electronics plug connected to it at one time; if so how? Thanks for your help in advance.

Gerald

Yes it can. Were you the one with the inoperable speedometer? I've found the best way to check the speedometer is to undo the bolt that holds it to the tranny, pull it out and give it a whirl with your fingers while having someone watch the instrument speedometer gauge. If it doesn't move than you know either the cable is bad/broken, it's not connected very well to the instrument cluster or the (rare) speedo gauge isn't functioning like it should.

If this isn't your problem, just reply and let me know. I thought there was someone here who posted a problem like this, but i didn't get a chance to reply and i forgot who it was.

I have a Ford F-150 and my speedometer is not working. I know it's not electrical, but I don't know how to pull out the speedometer to figure out what is wrong with it. Please help me. I don't really have the money to pay someone to fix it. Thank you.

The speedometer head is the last thing to suspect. The exception would be if the odometer still works.

First suspect the cable. They can snap or the square end at the transmission can round off inside the gear. You may be able to reach behind the instrument cluster to disconnect the cable, then watch or feel if it turns when you move the truck. It's often easier to disconnect the cable at the transmission, then spin it with your fingers while a helper watches the speedometer. That's also the time to inspect the end to see if it's rounded off.

The gear inside the transmission could be stripped too but that's not as common as a snapped cable. If the odometer does work, that would prove the cable and gears are okay. Usually when the speedometer head fails it gives a lot of warning first. The needle will typically bounce around a lot and the assembly will make noise. On rare occasions the head can lock up and cause the cable to snap, so if you find the cable is badly twisted, check the replacement for free movement with your fingers. A locked-up factory cruise control servo can do that too. They were run by the speedometer cable.

I understand this part. But how do I get to the speedometer cable to fix it. My problem is I am not sure how to get to the cable to check it. If you could please send me that information I would appreciate it.

Thank you,

If you're not familiar with what a speedometer cable looks like your best bet is to get a copy of the manufacturer's service manual. There will be line drawings and a description of how to remove the end from the transmission. You might find it on one of the online service manual companies too. My computer won't let me access them. I've never figured out why and I gave up trying a long time ago.

All of the speedometer cables in the '70s and '80s were pretty basic. Most had a metal cap that screwed onto the transmission. Typically you will need a pair of pliers to loosen it, then you just unscrew it and pull the cable off. You'll see the spiral-wound cable inside the casing. Spin that cable with your fingers while a helper watches the speedometer. If the needle flickers, the cable is okay.