Is this the only gauge not working? If so it could be a defective guage. Have you checked your fuse's? If the truck has been put through rough service( Off- Road) perhap's there has been some wiring damage.
I believe on the 92's there's a small fielding relay attached to the printed circuit at the back of the cluster, this may need replacing.
Don't know if this has been of any help, but it may point you in the right direction.
When in doubt :DON'T
Valley Station, Kentucky
Dream EXPression Racing