GMC Repair: 99 GMC Sierra Electrical Problem, brake light switch, gmc sierra

Question
I have a 99 Gmc Sierra with a 6.0 and automatic transmission.  My problem is When I apply the brakes the instrument cluster works fine.  When i let off the brakes I lose both temp gauges, fuel gauge, the square around the gear indicator and all the lights on the left side(like the hi beam indicator) The cluster has been replaced twice and brake light switch was replaced.

Answer
Hi
I looked at the schematics and it appears that alot of these circuits have a common grounding circuit, and they all terminate at G203. G203 (ground 203) is located on the left side (Drivers side) of the dash area, close to where the A Pillar meets the cab.This would be above the cluster on the inside firewall area. It is under the Dash pad, so some disassembly would be required to properly check the ground. I would check this ground. It is a splice pack ground, so there will be multiple grounding circuits meeting into a splice pack, and that pack is then bolted to the body.
Make sure all circuits doing into the splice pack check out, and then make sure the ground is clean and properly torqued.
I hope this helps