So... just driving along my instrument cluster and all the gauges will bounce or spin like crazy. Then it stops. I recently look at the battery terminals in the positive was corroded. Fixed that, or so I thought because it happened again. Now the oil pressure gauge does not work. All other gauges work except, of course, the nasty fuel gauge on the Blazers which never work correctly. I'll get new battery screws which should stop it but did I fry my oil pressure sending unit...or what?
All gauges go through the same fuse.
On a side note I have read that other than loose battery terminals the other causes could be faulty speed sensors for the ABS and believe it or not distributor needs to be replaced.

 

You might check your ground connection. Sounds like it's loose.

 

Everything works now that I clean the battery terminals. I just wondered if I fried the oil pressure sending unit. Would a faulty sending unit show up as an OBD code?

 

How old is the battery? Have it tested, because a bad battery can cause problems like this.