If it starts to dim on either side fix it asap 
No joke! it’s a serious problem please get it fixed
2009 Hummer H2 owners and New style 2007 and up Chevy Tahoe, Avalanche, Pick up Truck owners if your Digital Display is starting to dim or you can no longer see the mileage displayed or PRND321 is missing etc. You need to get this fixed asap or you will cause serious damage to the speedometer cluster or worse your Vehicles entire electrical system. This can cost you thousands of dollars in electrical repair if you wish to ignore this Warning! This is a ten minute fix once removed from vehicle by you and we charge $100 to fix it. Please do not ignore this warning. You Heard it Here First.
If you can no longer see any digital display on either side of your speedometer cluster it might already be to late to save the damage already done. If you wish to ignore this warning and keep driving the vehicle with no display it will 100% cost you hundreds if not thousands in repair work.