The illumination lights on my instrument cluster/panel are not working at all?

Joe,

Thanks for the help and the wiring diagram. The wiring diagram was most helpful, problem solved! Some feedback about the issue follows.

Originally, the first thing I did was check the fuses in the manual and came across Fuse #4, which was good, for the Instrument cluster, DRL Relay (I had disconnected the DRL to kill the Daytime Running Lights, fuse 15 is also for the DRL relay), Lamp Switch, Keyless Entry, Low Coolant Module, Illuminated Entry Mode, and DRAC (Diesel Engine). I also checked Fuse #9 for various lights but not the instrument cluster lights just in case. It was also good. Fuse #9 also supplies power directly to the Headlight Headlamp & Panel Dimmer Switch (HPDS) itself [presumably this is the "Lamp Switch" label in the manual on page 6-62, copy attached], which in turn provides power to the various lights via the headlamp/parking light switch on the HPDS and to the Dimmer Rheostat and Parade Mode Switch but without having the wiring diagram in hand, one would not know for sure that "Lamp Switch" is actually "the HPDS" itself and is powered through this fuse, which is the key to the whole problem. Since Fuse #4 included the "Instrument Cluster" and Fuse #9 powered the HPDS, I stopped there and missed Fuse #14 on the next page, which I found out later after having the wiring diagram in hand, includes simply "Cluster" and "Radio Illumination" among other items, which in the end were the culprits I was trying to track down. There is an additional wrinkle to all of this as well.

In checking the diagram you sent in addition to the yellow highlighted line tracings and red markups you had put on it, I studied the diagram and noticed on the upper left side just below the rectangle of the HPDS, of which I had sent you an actual picture, the Display Dim Sig(nal) [Radio] and Display Dim Sig(nal) [Instrument Cluster] boxes. These are fed via the combined thumbwheel for the Rheostat and Parade Mode Switch on the HPDS with the rheostat controlling the Radio Illumination and Instrument Cluster Dim Signals and the Parade Mode Switch directly feeding both to full brightness and overriding, if you will, the Dim signals, which is exactly how everything actually works and I am presuming then that the Dim signals are controlled possibly via the Body Control Module (BCM) or there is a current line missing from the drawing, which I have drawn in by hand in blue in the photo of the marked up wiring diagram attached (if you can shed any light on this [no pun intended], I would appreciate it). The reason I say this is that once I had the wiring diagram you sent in hand, I checked Fuse #14 and found it was blown and then went back and looked at page 6-63 in the manual (copy attached) to discover what it fed and discovered the "Cluster" and "Radio Illumination" labels. I replaced the fuse, and the lights were still out so I then replaced the HPDS altogether and everything worked as it should. Puzzled, I did some more trouble shooting and found that both Fuses # 9 and #14 must be good for the Radio Display and Instrument Cluster lights to be working either in dim mode or on full bright. So, I am thinking I had a dual failure in that the Rheostat shorted and failed and blew Fuse #14 in the process. Go figure.

I look forward to your reply on the BCM vs. Missing current line question above.

Thanks much again,
M.