ok guys i have installed a lunar electric tranny temp gauge into my ac vent... heres the problem...all wiring is correct...on startup the needle pegs over to the right and stays..so i took the wire off the sender and grounded it and then when i start her up the needle stays at 0 (left) but doesnt move...whats bad? my gauge or sender or niether

 

sounds like you fried your gauge

 

Sounds like the sender wire on the back of the gauge is touching one of the other posts, either the + or - . I've done the same thing before.

 

I had the same problem with mine, after buying 2 add. guages (dumb move) I realized my sending unit was bad. With that being said I have 2 trans guages for sale for 50 shipped picture below

 

Check the wire to make sure there isnt any cuts in the cover. Prolly around the firewall or wherever you routed the wire out. My gauge pegged after i installed it and it ended up being a bad spot in the wire and was touching the firewall.