Instrument Cluster Home-repair
I wanted to write a thread about this here so others could find it, I researched a lot and found this method in one or two random places on the internet, but not too many details, so here it is:
I was having a problem in my 2005 focus ZX4. The lights and gages on the instrument cluster/speedometer were acting up: some lights going on when they should not have been, sometimes even when the car was turned off. I read that this is a common problem in the focuses, corrosion forming on the board and shorting out the circuits. This is what I did after reading this on a blog, it was pretty simple.
I removed the dash panel under the steering wheel in order to access the bolts for the dash panel that covers the instrument cluster, then removed that dash panel too. I removed the bolts that held the cluster in place, unplugged the harness in the back of the cluster and removed the unit. I then took the back panel off of the cluster to expose the circuit board. There was noticeable white corrosion/sediment stuff on the board. I sprayed the board with electrical contact spray from any auto store, lightly rubbed it clean with a paper towel and let it dry overnight. Put it all back together and havent had a problem since.
saves the $600 ford would charge to replace the cluster.
hope this helps someone. good luck.