Instrument cluster lighting

Oh boy, I just went through this with my '92 Lesabre, took a long time to trace it all down, and wound up splicing in a new wire just to my instrument cluster lights. A short kept blowing fuses somewhere in that circuit.
Down where your feet go, up under the dash at the fuse panel, there is a 15 amp fuse for park/tail lights. When you hit the light switch (for heads or park lights), power is sent to that fuse, and then to the exterior park lights. There is another wire from that fuse (green wire on mine) that also goes up under the dash, and splices to several bulbs-on the radio, on the HVAC controller, on the ashtray light, also one to the under hood lamp, and then one to the dimmer/brighter switch on the dash, the rheostat that controls brightness of interior lights. One of the green splices goes into this switch, and then another wire goes from this switch to the instrument cluster for the gauge and dash illumination. I couldn't find the short, so ran a new wire from the park light fuse to the gray wire to the instrument cluster for the cluster bulbs. I bypassed the dimmer, and left off the HVAC bulbs and ashtray light. Too much trouble to wire them all up, and think my short may have been in the dimmer rheostat.
If you have a voltmeter, pull out the dimmer switch and check for power on those wires, the green from the fuse. The park light must be switched on, or the fuse has no power. There be 8 or 9 wires on that dimmer rheostat-I never did figure out where all of them went. Asked all over a Buick forum, but nobody had an answer.

If you think there is a problem with instrument cluster, unplug the instrument cluster, see if it still blows the fuse. Could be a wiring circuit problem, somewhere? Maybe fuse box issue?
Sometimes, I use a test light in place of the fuse, to keep from blowing all my fuses. If the test light comes on, the circuit is going to ground, somewhere. If the instrument cluster is unplugged, then hopefully, that is ruled out.

Your instrument cluster and console lights are protected by fuse #2 (15 Amp) in the underhood fuse and relay box. They actually get power from the tail lamp relay. If the tail lamps are working, the relay and the fuse is not your problem. The brightness of these lights are controlled by the Multiplex Control Unit and theCPU built into the instrument gauge cluster. The dimmer circuits are actually integral with the instrument cluster. If the tail lights are working and the lighting in the instrument cluster is working, then the problem is either a CPU failure in the instrument cluster or an open circuit between the instrument cluster and the center console lights. The console lights themselves should have power all the time that the tail lights are turned on. The CPU in the instrument cluster provides ground for them to function. The wiring is a little different depending on which model you have and how it is equipped (LX, DX, EX, LX with side curtain airbags, etc.) however, the function is the same.

I highly recommend scanning your computer network for fault codes before spending a lot of time trying to perform electrical diagnosis. There may be a fault code present that will lead directly to the cause.

Try to remove the instrument panel and disconnect the harness to see if doing that gets rid of the blown fuse when starting the car. If it does, then the instrument panel should be replaced with another. If the fuse still blows when starting, then there is a wire shorted to ground somewhere.
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Instruments and Switches Instrument Cluster Removal & Installation To Remove:

1. Remove the instrument cluster trim plate.
2. Remove the instrument cluster mounting screws.
3. Rotate the instrument cluster rearward and lift up on the top of the cluster in order to disengage the locating pins.
4. Disconnect the electrical connectors from the instrument cluster.
5. Remove the instrument cluster.

To Install:

1. Connect the electrical connectors to the instrument cluster.
2. Position the locating pins to the holes in the instrument panel.
3. Install the instrument cluster by rotating the top inward.
4. Install the mounting screws.
5. Install the trim plate.

That fuse also supplies illumination to the radio, hvac controller, cup holder and cigarette tray. I think the best thing to do is start unplugging each one of these until the fuse stops blowing. Then plug the last think in that you unplugged to make sure that makes the fuse blow. If you suspect the instrument cluster start with that first.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

unplug the instrument cluster. If it now does not blow, replace the instrument cluster. If it stll blows then you need to trace the wire in the loom looking for where it touches metal or have several wires melted together.

Here you go. Under hood fuse block
Ign. Fuse E
and
ipc/dic
both fuses are 10 amp
I hope this helps. Take care.

Check Fuse box Number 30 which is a 10Amp fuse
& number 15 which is a 7.5amp fuse.
you met have a blow fuse.
If good
Did you check the dimmer on the head light switch Pull out to see if you have power on cable color orange / blue. (Pin 9)
If this is good
Pull cluster out to see if you have power on plug pin 3 in instrument cluster this there..
If you have power
than replace the llumination bulb or cluster.
Very rare to find a ground poblem here.

Checked Every fuse in the fuse box (no small task).This includes #4 - Power point Instrument Panel, #14 - Day time running lamps (auto lamps doesn't work nor does auto lock), #27 - ignition switch run feed, #35 - Instrument Cluster, #41 - Instrument Cluster, #42 - Delayed Accessory, #45 - Ignition switch run/start feed, #102 - Door locks body security module, #103 - Ignition switch, #110 - Ignition switch, & #116 - Ignition switch. But I also check all other ones as well, they all register OK. AC panel & radio work. Turn signals work. Mileage does not work, trip computer does. So, basically, everything works except auto head-lights, auto locks, and the dash cluster (no MPH, RPM, mileage display, Fuel, Temp, Tran Temp, and Oil Pressure).

i would check the grounding wires. have you tried going to higher ampage on the fuse? There is definitely a short somewhere