I’m going to venture and say that this subject has been covered before. If it has I can’t find it. Here’s my issue: 2005 Silverado 1500, instrument cluster, HVAC and 4X4 selector buttons have no illumination. They function properly, well except for the oil gauge (its pegged) and PRND12 is very dim, but those are other issues. I have checked every fuse and got a new dimmer switch. Does anybody have any ideas or suggestions? Anybody with the same issues?

 

some of the gm trucks had a separate fuse under the steering column for back lighting on the cluster, think it was a 2 amp fusible link. its not listed in most service manuals. they hid it well, and tapped it off to the main ignition harness

 

I have the same problem for my 2005 Avalanche. I haven't located that fuse the speedOhead mentioned. My instruments work fine. I have no back lights and no PRNDL. Also, my 2wd/4wd indicator lights do not indicate. However, when I turn the ignition to On position, the Neutral light between the 2wd & 4wd lights. My message display (Below the PRNDL Display) works fine, dims when I apply the dimmer, gets brighter when i turn the dimmer up. I feel confident that the dimmer is functioning properly. When i engage the 4wd or go back to 2wd, I can hear it / feel it shift. If I drive it , I can feel it in the proper drive selection (2wd or 4wd). I have pulled the IPC, examined front and back side of board with 10x lens. I find no burns, cracks, bad solder joints, burned or broken chips or transistors. the board looks to be in excellent shape. Any suggestions would be awesome. From reading the posts, I joined a great group. Thanks!!

 

i'm sorry, i gave out wrong info on back lighting fuse. that fuse i mentioned is only for the steering wheel control lights. though these clusters are know to lose some back lighting, not common for all bulbs to go out at one time. Gator6, while looking at the back of the board did you notice any black spots? these clusters are know for corrosion on that back side that can create issues

 

speedOhead, I went through in finite detail on both sides. I will get it apart and post pictures of what it looks like. However, it looks pristine. I used a 10x lighted magnifying glass to inspect the board and could not find any issue with it. I just bought the truck (in bright daylight). Are the door buttons supposed to be back lit as well? They aren't. It would be nice to see what I should be looking at as far as what is lit and what isn't. Thanks

 

alright, i pulled the wiring diagram thru work and this should help a little. the dimmer switch looks to go directly in to the BCM (body control module) and from there it looks to break out into two separate wires to the cluster. poin A 11 should be the dimmer wire only for back lighting of the cluster. the voltage on the wire should change when playing with dimmer switch. the other wire which confuses me a little shows to be brown/white is used to dim only the LCD's of the cluster. what confuses me is that this wire also shows to be the CEL turn on wire. and btw according to the diagrams, all door buttons should light up

 

I was just able to download the same diagram and I agree with what you say. I hadn't resolved for the door buttons, so I have a common issue (no back lighting at all). I still feel very confident the Dimmer is working and working properly since it dims the computer display module (I don't know the right words). The display that tells you mileage, Odometer, other feedback from the computer. It dims properly when I adjust the dimmer. If I could figure out where to find A11 and A12 then i could put a test lead on it. I wonder if I have a bad ground at G200? I don't know where to find that. Hey thanks for your help.

 

pin a11 you can find on the plug for the instrument cluster

 

Thanks speedOhead for you r help. I have it resolved (I think). I connected 12vdc to the A11/12 leads. One light came on. I decided to check resistance on the other bulbs. They all showed they were good (about 4 ohms each). I decided to apply 12vdc to one of the bulbs to see what would happen. They should have all lit but one. Instead, only a couple lit. I applied voltage to another bulb of th ones that didn't light up. It lit up along with a couple of others. I then proceeded to check the rest of the bulbs using the same procedure. I got the same results. I concluded that the board is damaged in several places even though visual inspection fails to show it. That being said, I decided to this was beyond my capabilities. I sent the unit and the 2wd/4wd cluster to Circuit Board Medics. This will insure the job is complete. They will test the board, calibrate it, change out all the bulbs to LEDs, install the Tranny Temp gauge and warranty their work plus get it back 24-48 hours after receiving it. That is a big relief. The board is already on its way to them. I will try to remember to post here when it gets back. Thanks to all who scratched their heads on this.

 

sounds good, if you have any problem with the repair. check out my company. southernelectronics.com. glad we could help