1983 c10 Silverado Temp Gauge Problem

I have a problem with the temp gauge.
When the truck starts, the gauge goes right to the middle, then after warmed up, gauge drops.
Could it be a wiring problem?
Thermostat is working.
Please advise - any help is appreciated.
Also, where is a good repair book for this truck?
Thanks!
Bodabing

One year online sub.
http://www.alldata.com/products/diy/index.html
Your local auto parts places have haynes and chilton books.
Ebay has a lot of books.
Check your tempt gauge sending unit to start with.
MT

I think you have one of two things going on here.

1. You could have a bum gauge.

2. You may have the sending unit for a dummy light
instead of a gauge

move the temp gauge wire and sensor around under the hood. It may be loose or corroded.