After lots of frustration with the speedometer in my '94 Pathfinder, I
finally took it apart to figure out the problem.  I'm posting this in
an attempt to provide information that might help others.

My symptoms were that the speedometer would read low - about half of
the proper speed.  This problem happened most often when the vehicle
was cold.  After driving about 15 minutes, the problem would clear up.

I searched the internet and found several people that reported similar
symptoms.  I also found several suggestions to replace the speed
sensor - a $60 part.  Initially, I did this but it did not solve the
problem.  Now that I understand the problem, I can tell you that if
your speedometer needle is moving, you don't need to replace the speed
sensor.

It turns out the problem is a defective IC in the speedometer head.
The IC is an AN8363 made by Panasonic.  This is a custom IC and you
can't buy it anywhere.  I traced out the entire speedometer circuit
and I designed another circuit to replace the broken function of the
AN8363.

I'd like to post my information, including pictures, so that other
people can benefit from this.  If anyone has a suggestion where I can
place this info, please respond to this post.  Sorry, I'm not
providing my email address because doing so guarantees a lifetime
flood of spam.