I have a 2002 pointiac sunfire; I cannot read my odometter, the gauges do not move, and the brake light stays on. Do I need to replace my Insturment cluster or could it be the result of something else? The car has been sitting for several years. If I change the cluster do I need to have the dealership code it with the car?

Having a factory or professional type scan tool hooked up checking DTC'S - diagnostic trouble codes in all the modules on the vehicle . Insturment cluster , PCM , BCM ,ABS , SRS etc.... Should be the first step in the diagnostic procedure.. Could have a serial data network problem . Do you know what a serial data buss is ? In the case of your vehicle it is GM class 2 data buss . Anytime a bunch of thing's electrical wierd out , suspect the buss.Buick , chevy , cadillac , olds , pontiac all used this .
Buick Class 2 Operation Diagnosis 1998

Dear Sir>
Please see the schematic attached, proceed with logic system for troubleshooting and fix it. Look for loose connection, corrosion, dirty, dust, vibration, burn or break wires, defective relais or pump.
God bless you

ABS light on did they check codes ? The light staying on an no codes is usually a insturment cluster problem not the EBCM - electronic brake control module . No relay in side the module , a transistor or diver as they call them . This transistor will supply a ground on a electrical circuit from the brake lamp driver module ,when it does this the brake lamp driver module ground a electrical circuit for the ABS light . If anything is bad causing the ABS light to stay on it would be the brake lamp driver module . Your best bet ,take it to a GM service dept.

check your fuses, bulbs, and relays for the taillights and insturment cluster, normally when lights go out randomly its due to a bad fuse or relay or bulbs

i check brake switch by the brake pedal

I just reset my maintenance light and started the car to find a flashing airbag light. Reading the manual, the SRS checks a lot of things so I pulled each seat belt out to full and retracted about 3 times each, then moved front seats full forward and looked from the rear for connectors -- saw them all connected, but jut pressed them together to make sure, moved seats back. Finally, closed all doors, buckled belt, and crossed fingers starting car. Light lit for 6 seconds solid and went off. Hoping it stays that way. Had squib replaced under warranty in year 1. Now fearful of any repair since so $$$$ and you gotta have working airbags and not unforseen inflation. Hopefully light stays off ... hope it works for you.

Ey sounds like you have a bad alternator so you should test to see if the alternator is still good or bad by let the engine running then pop the hood opened and disconnected the ground cable off from the battery terminal so when you do that and if the engine dies then you have bad alternator but if the engine still running after disconnect then your alternator is still good

Check coolant level, and possibly replace thermostat. When a thermostat gets stuck in the closed position, coolant does not circulate thru motor. Gauge stays midrange when driving, because motor is being cooled by air and or the fan. If car seems to operate completely normal, then the gauge is faulty.

it is not the BCM, go to any Kragen or Autozone parts store, have them test the alt, the test is free

Bonnie, this is the traction control light, there is many reasons why this could be on. The easiest way to turn it off is to pull the emergency brake, this would usually disengage the traction control. This is not, however, a fix to your problem as to why it is on.