Speedo issues - help!

Mack · Oct 19, 2013

Hi guys,

Today I took the Mustang out for a spin, for the first time since the big trip to France (where I had no issues).

I noticed my speedometer was doing weird stuff: it would point to the right speed, then drop dead to zero, then again to the speed, then again to zero. Especially when I let go of the gas, it drops to zero and stays dead. When I powered up, the needle went up and pointed to the right speed, until a few seconds later it drops again.

I also noticed that my mileage counter (both of them) are not counting. The rev counter and other gauges work fine.

The car stalled 3 times on me, but not sure if that's related. I did have the batery inplugged while parked, only plugging it in just before starting the car. Not sure if that did anything.

I'm not a technical guy, but I don't want to run to a garage for every little thing. I want to learn. The problem sounds like a loose connection somewhere, but where do I check?

I really hope it's nothing that needs the dashboard to be taken out...

If you can point me to some simple checks I can do myself, to see if there's a loose connection somewhere, please! Please describe so a noob like me understands.

rz5.0 · Oct 19, 2013

There are small gears inside the cluster that need to be changed. They get old and strip.
http://www.latemodelrestoration.com/item/LRS-17255OG/94-98-Mustang-Odometer-Repair-Gear-Kit

CC'S95GT · Oct 19, 2013

IMO. The problem is the plastic gear on the vehical speed sensor (VSS).
They will wear out over time especially if you've changed the rear end gears to anything 3:55 or higher because 23 tooth conversion gear isn't a perfect match to the steel gear in the trans.

If you cruise control works then the problem is the gears behind the cluster.
If the cruise control doesn't work then it's the VSS gear.

Mack · Oct 19, 2013

CC'S95GT said:
IMO. The problem is the plastic gear on the vehical speed sensor (VSS).
They will wear out over time especially if you've changed the rear end gears to anything 3:55 or higher because 23 tooth conversion gear isn't a perfect match to the steel gear in the trans.

If you cruise control works then the problem is the gears behind the cluster.
If the cruise control doesn't work then it's the VSS gear.

I have 4.10 gears so your story can make sense. I'll try the cruise control next time I take it out. With "doesn't work" do you mean the cruise control does not maintain the speed?

CC'S95GT · Oct 19, 2013

Mack said:
I have 4.10 gears so your story can make sense. I'll try the cruise control next time I take it out. With "doesn't work" do you mean the cruise control does not maintain the speed?

correct. when you "set " the cruise to the desired speed and it doesn't hold at all.
Once you get the gear it's an easy fix. you'll probally have to get it from one of the Mustang sources because it's not a Ford part.

Orange 94 · Oct 19, 2013

You need a new flux capacitor.....

Its likely either what rz said, the plastic gear in the cluster.
Or its what CC said the speedo gear.

The speedo gear is easier to change I believe. I'd try what CC said, or simply crawl under the car and pull the gear out and check the condition.
If its the cluster gear its not the end of the world either. Both parts are really cheap and it will just involved a little labor on your part.

Good luck!

Mack · Oct 19, 2013

Thanks for the answers!

I'll try the cruise control thing. I think the most difficult thing will be locating the right parts and finding a company that ships to Europe.

mavisky · Dec 26, 2013

Bringing this back up.

I've had similar issues with mine lately. Gears look good in the cluster, cruise control works correctly, but here's where mine differs.I

I've done the gear swap on the trans output shaft to correctly match my 3.73's, but my speedo will either read correctly, or it will spin all the way around and max out on the peg below 0 (indicating 200+ mph). I'm also getting the non-functioning odometer even though my speedo shows i'm doing 200+mph

Currently I'm running a GPS speedo app on my phone on a dash mount when I drive the car as I can't figure out what's causing this issue. Anyone ever run into anything like this before?

Mack · Dec 26, 2013

I can't help you yet, unfortunately. I order the speedo gear thingy, but the car is still in the museum so I haven't been able to fix it (or to check if this fixes it)

CC'S95GT · Dec 26, 2013

mavisky said:
Bringing this back up.

I've had similar issues with mine lately. Gears look good in the cluster, cruise control works correctly, but here's where mine differs.I

I've done the gear swap on the trans output shaft to correctly match my 3.73's, but my speedo will either read correctly, or it will spin all the way around and max out on the peg below 0 (indicating 200+ mph). I'm also getting the non-functioning odometer even though my speedo shows i'm doing 200+mph

Currently I'm running a GPS speedo app on my phone on a dash mount when I drive the car as I can't figure out what's causing this issue. Anyone ever run into anything like this before?

I've had the same issues with mine too. I believe it's an issue with the cluster itself.
Mine works better now but sometimes still indicates incorrectly at both the tach and speedo but not usually both at the same time. It does work better after the cluster has warmed up. Usually a tap or 2 on the face will set all the needles properly.
I pulled the cluster out and slid a couple pieces of paper behind the area where the circuit board folds over where the harnesses clip in. This tightens to connection the harness is making to the PCB and that seems to make it much better although didn't fix it perminately.

mavisky · Dec 27, 2013

Yea it seems like an issue with either wiring or the connection to the cluster as it works perfectly other times. The last time it did this I removed the cluster and tore it down, then put it back in having really fixed nothing since all was in perfect working order.

Mack · Jan 11, 2014

Due to my car being in the museum I could only fix it today. A friend of mine ordered the stuff and sent it to me, as LMR does not ship to Europe.

I'm not a mechanic, I've never worked on cars, but this fix seemed so easy I gave it a try. And it worked! I'm very proud of myself now

I replaced the speedometer gear-thingy and now my speedo and my mileage counter works again. Very pleased!

Old and new:

So thanks everybody for the help, and I can now say: I MENDED SOMETHING!

[video=youtube;s2a1z4iFc9o]http://www.youtube.com/watch?v=s2a1z4iFc9o[/video]

CC'S95GT · Jan 11, 2014

good job.
Plan on replacing that gear about every 20,000- 30,000 miles because it's not a perfect match to the gear inside the trans.

Vettn71 · Jan 27, 2014

This is the closest thread I could find. I have a 95 GT. Speedometer and odometer doesn't work, tach, cruise does. It did work when I first bought the car (in December) but died almost immediately. Does the odometer drive the speedometer also, or is it independent? I replaced the dash, and the cluster and connections looked good. Didn't have any effect. I know it's probably simple, but I'm missing it

jim

Mack · Jan 28, 2014

When my speedometer didn't work, my odometer also didn't work. But with me, the cruise control didn't work also. It was fix with the gear-thingy.

I would look for your issues in the cluster itself. But I'm no expert.

mavisky · Feb 22, 2014

Vettn71 said:
This is the closest thread I could find. I have a 95 GT. Speedometer and odometer doesn't work, tach, cruise does. It did work when I first bought the car (in December) but died almost immediately. Does the odometer drive the speedometer also, or is it independent? I replaced the dash, and the cluster and connections looked good. Didn't have any effect. I know it's probably simple, but I'm missing it

jim

That's about the same issue I'm still dealing with. I'm going to have to start checking voltages as I'm afraid that there may be a damaged wire somewhere.