Instrument cluster issue

[281GrnSnake]

Hi all. I just bought a 99 Cobra and I have a minor issue with my speedometer. When I'm driving it seems to display the speed consistently, but when I come to a complete stop it jumps before coming to a rest at 0mph. All other gauges appear to be fine and don't do anything strange. Is this a bad speed sensor? Just want some opinions before I spend a bunch of money trying to figure it out myself. Any input would be greatly appreciated!

 

[shurur]

Probably not related..but...there are some cold solder points where the ribbon cable comes in. They are on the cluster pcb. They need to be touched up.
Usually the odometer goes out on that problem. It is a common problem.

My tach used to jump and I had a speedcal..after resoldering those two points...it appeared to go away.

Also check all your cluster grounds...blk or blk/wht wires with a meter.

 

[281GrnSnake]

Hmmm. That makes me wonder. I guess I'm not sure if the car ever had a speedcal. The previous owner put 3.55's in it and while driving it home, my buddy who was following me said I was doing around 5-6 mph under the speed limit while the speedo said I was right on. Wonder if that might fix it then....Do you have to get a tuner to do a speedcal on these cars, or can I just get a chip?

 

[shurur]

Speedcal is a module that is between your transmission vss/oss and the cluster/ecm....
It should be under your shifter bezel/boot inside the car. It has dip switches; so you can set it to new values yourself.

Aside: usually the speedcal is powered through the constant cig. Lighter power
It should be reconnected to the switched traction control power; so it will refresh each key turn.

I had to do this...think I tied to traction control ground and added a chassis ground as well..but don't remember..

It's sunday..others should chime in soon..

 

[scottydsntknow]

The OSS sensor is like $17, you could try to replace that and see if the problem goes away, that's the first thing I would do. If not then its probably a short somewhere or the cluster might be failing. It happens...

As far as the speedo... well these cars really wake the hell up with a good tune so you might as well get a tuner/tune and the speedometer can be re-calibrated there without needing to wire stuff in. Just don't buy Bama or any other "tunes for life"... go with something that is actually tuned locally on a dyno or a real remote street tune.

You can go ahead and see how far you are off with a GPS speedo app on your smartphone too. And you can ALSO pull up the speedometer on the digital odometer too, google how to do it so you can see if the digital readout jumps when the actual speedometer needle does.

 

[281GrnSnake]

Hey guys. Thanks for all the input. I think I might just replace the speed sensor and see if that takes care of it. Thanks again!