Hello. Im trying to help my friend which has a 2003 Monte Carlo SS. He just recently got it and me being the nice friend I am, I decide to help him install his bypass for the old radio and install his after market deck. Everything was great but then all of a sudden his dashboard lights went black, his AC/Heat lights went black, and his turn signals stopped working. The gages and everything still work, its just the lights to show how fast you are going stopped working. This was all at night so no clue if they will all turn on in the morning.. Please help!!

 

First check the fuses to see if any of the fuses blew. Make sure you reconnnected the 4 ways to the button on the dash piece too.

 

what is the 4way piece? and this morning like I thought all the lights and turn signals were working. We checked the fuses inside the driver and passenger side fuse boxes and all the fuses seemed to be fine. Could it be a relay or the BCM?

 

It is the triangle button, but if they were working today then it wasn't that then.

 

yes and now that night has fallen the turn signals are now working but dash lights still aren't. we hooked up his subs with a capacitor and then the tailrunning lights stopped working... but we thankfully found a fried fuse that caused that one. but the big issue is still the dash lights not working only at night

 

It could be the Headlight/Dimmer switch.

 

wait the dash lights come on during the day, but are off at night?

Sounds like some wiring got switched around for the ambient light sensor (terminology?) and now when the sensor thinks its night, its actually the day and vis versa.