2003 Chev Cavalier 20K original battery dead after three weeks of non-use. AAA jump - Wal-Mart new battery – dash warning lights won’t go out, even when engine off. Wal-Mart no answer – to private Chevy-trained mechanic – diagnosis ($150) $1100 estimate to install new cluster – to Chevy Dealer fro 2nd opinion (don’t tell of first) same diagnosis for $75 – send cluster out for rebuild – total cost of repair $412. Neither first mechanic nor Chevy mechanic had any idea what caused problem (dash warning lights to stay on when car not running) Could new battery installation have had anything to do with it? And, if so, might Wal-Mart be responsible?
Installing a new battery is not likely going to damage your gauge cluster. You might be able to save some money on a new cluster by finding one in a scrap yard though.
Momentarily installing the battery backwards (negative to positive) could certainly blow the instrument cluster. But it would probably blow lots of other things too…
There may be voltage backfeeding from the alternator due to a bad diode inside it. The warning lights may be tied into the alternator circuit so they can be tested when the ignition switch is in the ON position and the engine not running. Try disconnecting the small wire connections to the alternator and see if the lights go out. If they do then replacing the alternator may fix the trouble. Be careful working around the main output lead of the alternator since that wire ties to the battery and is ‘hot’ to ground.
If that doesn’t fix the trouble then there may be some bad blocking diodes in the cluster causing the trouble.