Dash lights and interior light went out. on 1991 GMC Sonoma

I've checked the fuses on this and all is well on these. Any suggestions for testing purposes?

Asked by for the 1991 GMC Sonoma
I would check the headlight switch and dimmer switch. It's best to have a wiring diagram to test these so you know which wires to check. You can get a good wiring diagram here:
You can use a test light but a voltmeter is preferable.
Check the power wires that go from the headlight switch to the interior lights.
Good Luck!
still no luck on this situation, Bret! All was checked, including the fuses....
1 more answer , 1 more comment
As far as interior lights,my '91 Sonoma has rubber grommets around the door switches that have deteriated,letting sand,dust,etc. get into switch.Just spray some lubricant in there & push in/out & see if dome light works.
That's one thing I haven't checked....I'll try that...right now, I'm using a 'punch domelight' to light up the maddening...