2004 Olds Alero

I installed a stereo in a alero and now I am getting a check engine light and the dash lights no longer work. I am getting two dif stories as far as what harness I should of used. The one I purchased plugs into the harness and has a big black box with a speaker in it for the chime. However when going to a dif location to purchase a kit (other place was closed) he tried to sell me a radio relocation kit saying that if the radio had rds I have to put the radio in the trunk. I am leaning toward the reloation but I just want to be sure. Thanks for the info Eddie

Put the stock radio back in in the factory opening. Does the check engine light go off and the dash lights start to work? If so then my bet lies with the relocation kit which is what my book shows me as well.Top Secret, I can tell you but then my wife will kill me.