Speedometer hangs at 50mph once warm

[JCat]

1998 Mercury Mountaineer 5.0

Once the vehicle has been driven for about an hour, the speedometer needle hangs at 50 mph.

Odometer works fine
Cruse works fine
Overdrive works fine

Whats broken or loose ?

Also,
I might have that cam position sensor squeak . . . are there any side effects that are caused by this problem ?

 

[gatzdon]

When the speedometer gauge is stuck, use an OBDII reader to see what speed the PCM is reporting. If the PCM reports a normal speed, then the issue is with your console, and you have eliminated all of the sensor inputs as a cause.

 

[intelisevil]

Is your ABS light ON? On '98 and later 2nd gens (and maybe some 3rd gens?) the rear ABS sensor (in the top of the 'pumpkin') is also the speed sensor for the speedometer.

I read a thread a while back where someone was having intermittent readings on their speedometer. They had some teeth missing on the tone ring (bolted to the ring gear).

Hopefully it's something as simple as the rear ABS sensor. $15-20 part, one bolt, one electrical connection.

Good Luck,