Speed odometer problem 98 SHO

[stoner930]

Guys.. I have a problem when i'm over 120mph in my car. The speed-odometer shuts down. It falls the whole way to zero until i let off the gas. What is causing this problem? I asked Ford and they don't have a clue, so they say. Do i need a new cluster? Is it a wiring issue. Is it fixable? Thanks, Don

 

[Xmann01]

Unfortunately its because of the way ford decided to get the signal for the speedometer in the 98's that it causes the weird operation. I believe they decided to get the signal from the wheel speed sensors which causes the problem. So I guess you shouldnt freak out about it as its not something "abnormal" for that year. I don't think you can fix it.

 

[Mr Anonymous]

Yup, it's a '98 thing. Glen Murdock had been working on trying '96, '97, and '99 ABS computers in his '98 to see if he could eliminate the quirk, but I'm not sure if he had any success. If I remember (and can find his email address), I'll inquire. In case you didn't guess, the consensus is that it's an ABS computer issue since the ABS system provides speed data to the PCM and speedo. Changing PCM's doesn't fix it, nor does changing GEM's.

 

[V6&V8SHO]

Just out of curiosity if the car has no idea how fast it is going after 120, does that mean that 98 SHO's have no speed limiter?

 

[Porkchop]

I'd almost be willing to try that idea out

 

[Mr Anonymous]

Just out of curiosity if the car has no idea how fast it is going after 120, does that mean that 98 SHO's have no speed limiter?

The PCM still gets the correct speed data from the ABS computer, it's just the speedo that drops out.

 

[Mac98SHO]

The PCM still gets the correct speed data from the ABS computer, it's just the speedo that drops out.

Not according to the several times (test on several occasion) I have run Real time data on my laptop at speed over 120 mph..... Though did I find this odd that the PCM had no clue, but did understand why the PCM could not see it do to the glitch that is inharent in the 98 SHO.

Now I have heard that the 98's are not limited do to this fact (have not tested myself.... do not have a straight enough road around here)......... just my 2 cents.

 

[SHO Dude]

When the speedo drops out, the odometer continues to work.

 

[afouras]

I owned a '97 and the same problem happened at about 110mph.

What would I need to plug my laptop into my car to run the same kind of diagnostic?

 

[Mac98SHO]

When the speedo drops out, the odometer continues to work.

This I have to take your word for, since I am not looking at the ODO at those speeds.... unsafe... I guess the only safe way to be sure is run it on a Dyno at 120... and see.

Honestly..... I know the car is fast... so thats good enough for me, just trying to make it quicker.

I just got new RIMS....

I will post link to OBD 2 web site later tonite. So you can get the cable.

 

[Mac98SHO]

http://www.obd-2.com/

Goto the above site. It works like a charm.

 

[Mr Anonymous]

This I have to take your word for, since I am not looking at the ODO at those speeds.... unsafe... I guess the only safe way to be sure is run it on a Dyno at 120... and see.

Honestly..... I know the car is fast... so thats good enough for me, just trying to make it quicker.

I just got new RIMS....

I will post link to OBD 2 web site later tonite. So you can get the cable.

FWIW, Ford has never to the best of my knowledge acknowledged the issue either. Any people I'm aware of that have taken their car to Ford for this issue were told there was no way for them to test the car at that speed legally, and even if there was they wouldn't allow their personnel to do so.