I installed some temp,oil,and volt gauges in my 1987 GL wagon.For the illumination I spliced into the dimmer switch so they dim.Note I said splice not cut the wire completly.I just stripped a bit of the coating off and soldered the wire for the gauge lights in.Now I have no dash lights.The lights for 4wd and the doors and the little headlights on the front of the car light up but the backlights are non existant.while the aftermaket gauges are nice and bright.So what happened?Would it help if I ran a fused wire from the battery to the dimmer?

I'm not sure, but maybe the wires off the light switch is a ground and you wired in positives to it? I really don't remember how they are, so don't take my word on it. Just something to look into.. You checked the fuses obviously, nothing wrong there?

The wire I tapped into had to be a power wire.I have a large ground that the gauges connect to.I know I have taillights when I turn the marker lights on( with no fuse)

If I remember correctly the dimmer control is tied to the hot side of the circuit. I don't have my info right now to check that.

 

The new gauge lights may be drawing less current than the dash lights. Does the dimmer control still work with the new gauge lights? If not, it would seem you are not correct wire for the dash lights. If the dimmer does work then remove the bulbs from the new gauges or disconnect them if you can, and see if the dash lights work ok then. If they do then you may need to change the bulbs to match the dash lights.

 

One thing to note is the dimmer control can handle only so much power. Adding more lights will increase the load on it and possibly damage the control if too much current is drawn. If you are only adding a couple of lights it will probably will be ok.