Hey ive got a 91 loyale. When i first got it the tach temp light did not work but the speedo light did work on the instrument cluster most/all of the other lights work...

 

a while back the spedo light stoped working

i figured it was bulbs blowing but not so

 

just swaped the bulbs and even swaped out the whole cluster no change

 

im stumped

is it some secret fuse

or perhaps the light whitch is broken....

but it was so strange one light then the other ????

any ideas would be great

It's entirely possible the cluster you swapped in was bad too, if you got it from a junkyard.

If the dimmer control is set to the maximum setting then you need to see if the control is getting any voltage. I assume you have already checked for any bad fuses in the dash fuse panel.