90 740 Dash board light problem

You need to check the connectors and wiring behind the dashboard. Fuse 5 supplies interior lights so will not be involved. The panel lights wiring involves a couple of inline soldered joints in the loom behind the dashboard (found by removing the knee panel or the instrument panel, then following the wires from behind one of the switches). I think they are Blue and Black.

All the best, Peter.

Try wiggling the shaft of the dimmer rheostat and see if the lights come on.

Are you sure? My '87 does, granted the '90 has a different dash but it would shock me if it didn't have a dimmer.

Sadly, "PK" is mistaken. The instrument panel rheostat is shown below,

That's the older style dash like my '87 has, didn't they update it in '90?

No, not till '91.

To the OP: If you remove the cluster and join the red and blue wires going from the circuit board to the dimmer together, the dimmer is out of the circuit. The dash lights then come on full bright only.

Well since he thought it doesn't have a dimmer it wouldn't surprise me at all if it just got turned down all the way while trying to set the clock or something.

You got it! Not driving this car very often, my daughter turned the dimmer down while she thought she was trying to reset the clock for daylight savings. When I looked quickly at the dash I was looking for a dimmer near the headlight switch. That little black post just blends into the dash. I've only had this car for 13 years DUH!!!! It has become easier to post the problem on this newsgroup than to give it much thought. Thanks to all.