Hello, and welcome to JA!!! I know you said you check the fuses, how about this two fuses?? radio. 15amp battery guard fuse , and the clamp 58 10 amp fuse??
When servicing the vehicle with the VIN you entered, the following diagnosis might be helpful if the vehicle exhibits the described symptoms.
Condition/Concern:
Radio inoperative with key on, auto door lock feature disabled, a/c compressor does not engage and DTC U1255 stored in the radio. Radio may work in rap or accessory until the door is opened.
Recommendation/Instructions:
Cause: Clamp 15A, fuse #10, 10 amp fuse blown to the BCM/PZM, terminal A11. This fuse is normally powered in run and not during cranking. When this fuse is blown, the BCM acts as though it is in the crank mode with the key on. The BCM turns the radio off via CLASS 2 and inhibits auto door lock operation. The HVAC control head inhibits a/c compressor operation.
CORRECTION:
Models:
(97, 98, 99, 00, 01 Cadillac Catera)
ASE Certified Technician
GM Master Certified, ASE Master Certified, 32 years exp, GM Hybrid Certified, GM Mark of Excellence
I did check these fuses, and replacing also, no change
shall I try checking under hood as recommended?
Can I log back in with findings or do I stay online until finished?
no need to check under hood. if the fuses are good. The radio in this vehicle is a class two device, that is controlled by the body control module. since the fuses are good, this will need to be scanned with a high end scan tool, like a GM tech 2 scan tool, for any codes in the body control module. there is a good chance there is either a problem with the radio itself or the body control module. unfortually the only way to check is with a scan tool.
Diagnostic Starting Point - Entertainment
Begin the system diagnosis with the Radio/Audio System Diagnostic System Check. The Diagnostic System Check will provide the following information:
The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.