2005 GMC Sierra check engine light

Hello everyone. I just finished my friends 05 sierra w/5.3 and viper 791xv/555L/456G. He has a light on the dash that is an outline of an engine block. I assume its the check engine light because of that.  The light comes on with the A.S. and when you just use the key. Took it for a ride and the transmission shifts fine. The truck just turned 3018 miles today . He does not have the factory radio in the dash so the info center is gone. Also the main overhead domelight is not working. The lights in the doors are fine and the bulb overhead is fine just no voltage. Is there a possibility of a main fuse blown somewhere that these two things draw from ,,or the engine turning 3000 miles saying it needs oil change? I have done other 05 tahoes and silverados and haven't had this happen. Any advice or insight is greatly appreciated. Thanks.

Did he pull the radio at the same time? From what I'm hearing there integrated into the BCM/ECM. I cannot remember which make/model but it actually USES the radio to enter the courtsy info. Sounds like you probably caught all the IGN/ACC wires but might check again if the alarm is outputing to them. Thanks for including the radio info, big help.. :) Good Luck

No  he actually pulled the radio out when the truck had 90 miles on it. But without it I am not sure that it just might need an oil change,,,lol. He is going to come by the shop after work weds. so I can triple check the acc/ign wiring again.

Yes, triple check the second ignition wire from the alarm/ =remote unit and make sure it's coming on! I heard it's a pretty expensive repair bill when it doesn't come on.Be careful whose advice you buy, but be patient with those who supply it.

Well I got her all buttoned up today. The second ignition was still in 2nd acc mode from the previous car he had it in so it cut out as the truck cranked a little change with the bitwriter and that was done. I started checking fuses and found a blown one and low and behold when I changed it the domelight came on. He failed to mention to me until tonight that the light stopped working while he was doing his sound system.