On my 2003 Chevrolet avalanche Z66 all my dash gauges stopped working my battery gauge is way past the 19 amp Mark and all the dash lights flicker even when truck is not running with the key out

Bad ground connection possibly . G - 203 ! Both radio an instrument cluster share ground 203 .
G203 In the I/P harness below the left side of the I/P near the A-pillar . Check to see if clean an tight connection .

Usually when these Gauges go out it is because of a faulty BCM( Body Control Module) The BCM controls all dash instruments . If it is the BCM you will have to get a dealership to flash the new one. Before doing that though check all fuses under hood and inside. It should say gauges or BCM

On most GM trucks the gauges fuse is in the fuse box in the side of the dash. You would see the panel to remove as you open the driver's door.
The info should be in your owners manual.

ok so for idle on new cars you cant adjust it but for the idle problem take out your idle air control valve and clean it with carb spray or replace it for sixty dollars and if you need more help lemme know

is it the lights of the gauges dont light up or the gauges dont work period? if they dont light up then check the bulbs that are behind the gauge cluster and they could be burnt out i have the flickering prob with my ac hvac controls and half the lights on my gauges dont light up due to bulbs being burnt out i just havent spent the money to get some blue leds to put in there

You have either lost ground to the gauge or your float is stuck in the tank. It is more than likey a grounding issue though.

Common problem on the 03-06 Avalanche instrument clusters, it's caused by failing stepper motors on the cluster's circuit board and it can be repaired. Check this page for more on how to get it fixed - Avalanche oil gauge fix

Sounds like the oil pressure sensor. Thatt is the easiest thing to change. If not its the gauge. Put voltage to the wires from the switch and see if the gauge stops jumping and stays pegged, if it does its the switch Good luck

I had the same problem some time ago, lights would go on and off, odometer appeared to stop counting at times rpm gauge would work and then not... power steering would off and on work and head lights would blink on and off when in driving light mode (off position).. The fix for me was I had to have the dash computer replaced (about $500). After doing this around 50k miles ago all the gremlins seem to have remained gone.. Hope this helps

my 2003 s-10 did the same thing. my problem was a low battery.i put a new battery and have not had a problem since.