PDA

View Full Version : Speedometer not working



RioCobra
10-30-2018, 04:17 PM
1997 Cobra
T45
Had the car out last week and noticed the speedometer wasn’t working.
Odometer worked
Tachometer worked
Trip odometer worked

Did some research and from what I could see, the problem is either in the cluster, or the VSS on the transmission, but would need to see if the cruise control works to go the VSS route.

Took the car back out today, and sure enough, the cruise control would not turn on.
The cruise control did work in August (Woodward....what a trip!)

So, is this in fact a VSS issue?
Some other reading mentioned that the VSS controls both the speedo and odo.

Any help would be appreciated

RedSN
10-31-2018, 05:50 PM
Sound like the VSS.
...or the wiring going to it.
...or striped speedo gear?

Snaketamer
10-31-2018, 06:13 PM
I think you're on the right track with the VSS. Had this problem with my '98 Cobra...sort of... Same symtoms as yours but after replacing the VSS, I still had the same issue. I tracked it down to the Speedcal in my car as it connected in line with the VSS. Ordered a new Speedcal and all was good again. Not sure if you have a Speedcal in your Cobra but, if so, check that also.

RioCobra
10-31-2018, 08:17 PM
I think you're on the right track with the VSS. Had this problem with my '98 Cobra...sort of... Same symtoms as yours but after replacing the VSS, I still had the same issue. I tracked it down to the Speedcal in my car as it connected in line with the VSS. Ordered a new Speedcal and all was good again. Not sure if you have a Speedcal in your Cobra but, if so, check that also.

Yes, it does have a speed cal for the 4.56 gears.
Any idea how to test if this is the faulty part?

Snaketamer
10-31-2018, 11:13 PM
I didn't test my Speedcal because when I opened it up, the curcuit board was coated in oil. I figured something let go(resistor?). I had got it used off of SVTperformance.com years ago and figured maybe it was time to go new. lol
Guess you could bypass the Speedcal. Your speedo would be incorrect but, may work.

RioCobra
11-02-2018, 06:04 PM
First checked the fuse for the dash, Fuse was good.
With the roads being crap, we put some jack stands under the rear axel to be able to test speed.

Hooked up a scanner, and was getting intermittent speed reading. Took out the VSS, it appeared to be ok.
Bench tested it with a drill and multi meter and was getting good voltage.
Installed the VSS, then bypassed the speed cal, and bango, the speedometer was working!

Need to road test it with the speed cal bypassed and test the cruise control.
The speed cal had a bit of a burnt smell to it.
It also had constant power run to it, instead of having power from an ignition source.
Cut out all the old wiring, and will hook it up proper.

May need a new speed cal.

Also, priced out a new VSS from Ford (not Ed), $167 + tax! Holy crap.

RioCobra
11-02-2018, 06:05 PM
So glad it wasn’t the cluster.

ZR
11-02-2018, 06:12 PM
Nice find.

RioCobra
11-04-2018, 07:17 PM
Took the car out for a rip today, cruise control woks!
Really weird to be on the highway and the speedometer showing 170kmh when I was only going 100kmh.

Now looking for a speed cal if anyone has one.

RioCobra
01-08-2019, 08:38 AM
Santa brought me a new Ford Performance speed cal for Christmas.
Will clean up the wiring, and hook up to a proper electrical source in the spring.
Now the long wait.

Snaketamer
01-08-2019, 12:47 PM
Glad to hear you got it figured out. Pretty easy fix once you know. Musta been on Santa's 'Good' list... :stickpoke: