My speedometer doesn't work and shows maximum speed all the time.

The torque convertor clutch (TCC) locks in after 55mph on my car (as it should) and this is activated (as I understand) by the speed sensor sending a signal to the ECM and the ECM sends a signal to the TCC to lock in the auto box.

So my speed sensor must be working to lock the TCC, right?

So question is - can it be my guage that is faulty?

Anyone know whether there is a common fault that is easily identified by the fact that my speedo is reading maximum speed all of the time?

Does your odometer work? If it does then your speedometer circuit is partially faulty. You will most likley need either the circuit board or the actual speedometer assembly. Could be something as simple as one of the conductive nuts on the back of the studs has come loose.

quote Originally posted by Fierobsessed: Does your odometer work? If it does then your speedometer circuit is partially faulty. You will most likley need either the circuit board or the actual speedometer assembly. Could be something as simple as one of the conductive nuts on the back of the studs has come loose.

Hi and thanks.

No, the oddometer doesn't work either, good point and I guess it could be a connection problem to the speedo unit?

Have you recently taken the speedo assembly out? Did you happen to lay it upside down? It happened to me. After having the unit out and upside down the speedometer needle pegs out and when you put the assembly back in it is stuck on 120 or 85 or what ever. But if you say that the odometer isnt working either well that sounds like a connection. First check the plug at the tranny.

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quote Originally posted by ohio86se: Have you recently taken the speedo assembly out? Did you happen to lay it upside down? It happened to me. After having the unit out and upside down the speedometer needle pegs out and when you put the assembly back in it is stuck on 120 or 85 or what ever. But if you say that the odometer isnt working either well that sounds like a connection. First check the plug at the tranny.

Wiring from sensor must be Ok since I get TCC lock out at 55mph - I guess that it's is either a wiring or connection fault to the speedo.

I'll check connections at the speedo and work back.

Thanks guys, it helps to discuss

burn a fuse?

If you pegged it from some power anomaly, then it won't come back until you get back to your max speed.

Try flipping the needle back to 0 and see if it comes back.

Because of the way the speedometer works, it's possible for it to get "stuck" at the high end of the scale. The motor is trying to move the needle back to zero via the closest route - which doesn't work because there's pins in the way.

There's a couple of ways to get it out of this situation - one is to remove the instrument cluster and manually move the speedo pointer to the zero position. The other is to get out on a open road and go fast enough that the pointer is within 90 degrees of the actual speed; that's about 85 for a 120 MPH speedo. When you get it up to that speed, the needle will jump to the correct reading and stay synchronized afterwards.