I own a 2001 chevy silverado and my gas guage doesnt work ac wont blow cold air cargo light does not work my emergengy brake light is always on the alert center flashes between saying low battery and cargo lamp lit and I have taken my truck to get a smog test and it fails every time because the OBD system wont turn on.....i have checked the fuses and the wire running to the firewall from my engine and they are all good.....any sigestions

SOURCE: 2000 Saturn SL2 fails smog due to failure of OBD Self test

Some vehicles require very specific drive cycles (called "drive traces" if you perform them on a road simulator or dyno) to activate certain self-checks like the catalyst and EVAP monitors. As a general rule, doing some stop-and-go driving around town at speeds up to about 30 mph followed by five to seven minutes of steady 55 mph highway speed driving will usually set most or all of the monitors. Consequently, if you're checking an OBD II system and discover that one or more of the monitors have not run, it may be necessary to test drive the vehicle to set the remaining monitors.

You should talk to a good emission tec, if this is not throwing a code, it is hard to say if that one of the components could be bad. O2,pump,convert, HeO2, every part of the emission system.

With a 1000 miles, and doing what is says above just before the test, and ending driving at the test
should be plenty. If it is not, you will have to have each emission part checked, or when the computer
is plugged in it might show a code that did not trip dash light.

SOURCE: Brake lights on a 2003 chevy silverado 2500HD wont work.

same bulb but 2 seperate elements. wiring diagram u should be able to obtain from your local auto parts store like autozone(preferred)

SOURCE: 99 Chevy Tahoe... Rear turn signals, brake lights, and hazards

I had this problem, and to be honest, it happened to the left side about a week later...it's the board that the bulbs plug into...it's a very common problem with this model. So popular that you can normally get the socket board off the shelf at a parts store! it's extremely simple to replace, and I replaced all the bulbs at the same time!