So my wife and I are slowly fixing replacing problems with our 88. Dash lights worked then suddenly they all stopped working. After this happened, when I turn on the headlights the bright indicator lights up but dimly and no exterior lights except for the headlights. Fuses are good. Bright indicator fully illuminates when bright switch is depressed. Obviously a ground issue. Unhooked by bright switch and found 4 wires in the loom, only 3 terminals for bright switch. Also found several other wires under dash pad cut or disconnected. My first job is to clean all the grounds I can find, but where are the dash grounds?

Here is the wiring diagram for the 86 GM chassis. 88 should be very similar.

http://truckroadservice.com/ba...ts/86_P30_wiring.pdf

The light switch has several parts and sends power to headlights, running lights and dash panel. My 86 also had a panel switch to flash the running lights. That switch fried and all my outside lights went out. With all the extra bulbs on the coach harness, my light switch used to run hot. Your light switch may have failed. Try turning the knob and measure the voltage coming out of the switch, the panel dimming resistor could be shot.

These were when I was replacing the gauges. Shows some of the wiring.







I can't remember just where the grounds were.

Good luck. When in doubt, run new grounds. They all connect to the same place, extras won't hurt.

I traced the wires from the bright switch and found that the White wire must have broke because a red was crimp connected to the white and ran to the switch.

This seems familiar but there are probably many headlight and other under dash splice threads over the years.

I have some wires that start as green, spliced to yellow, spliced to red then to black. Never assume!

Tere

IF YOU NEED A LAUGH , I DID WIRING REPAIR AND CURSED ALL THE SHORT WIRES .. IT DID NOT OCCUR TO ME TO MUCH LATER TO TAKE THE DASH OUT FROM THE FRONT . IT WOULD HAVE MADE IT EASIER

Lol Jack. Live and learn! Sometimes we do it the easy way, sometimes the hard way.

A while back I was standing on my head, draped over the seat in my Cessna 172, trying to wire in some new intruments in the panel. Miserable job... I asked my AP mechanic if there was any easier way. He said, Sure! The factory installs the panel, wires it from outside, then installs the front cowl and the windshield!

This is the argument for "fixin' to do it." You spend time thinking of an easier way, or better yet, someone to talk into to doing it for you!

Have Barth, will travel

Steve I love how nice and clean your wiring is behind the cluster. I have something to work towards.

Thanks. Small zip ties are your friend! When bundled the wires move around less. Easier to trace visually. Seem to be more reliable.

Doesn't take much time but looks better and works better!