GM-GMC: STEREO, haynes repair manual, gmc suburban

Question
A WHILE BACK MY STEREO STARTED CUTTING IN AND OUT, SO I TOOK IT IN FOR REPAIR. THEY COULDN'T FIND A PROBLEM. I BOUGHT A NEW ONE, IT WORKED FOR A WHILE, THEN SAME PROBLEM. THEY SENT IT TO DELCO WHO SAID THEY FIXED IT, DOESN'T WORK. THIS IS A 1999 GMC SUBURBAN, THAT HAS FRONT MIDDLE AND REAR SPEAKERS. IN THE MEANTIME I HAD AN OLD 1979 JEEP CHEROKEE RADIO/CB LAYING AROUND, I BOUGHT A PLUG AND  HOOKED IT UP, PLAYS OUT OF THE LEFT FRONT AND REAR SPKRS BUT NOT THE OTHER FOUR. TRIED PUTTING THE OTHER TWO RADIOS BACK IN NOT A SOUND. CHECKED CONTINUITY ON THE DASH HARNESS FOR EACH SPKR PAIR LFT FRT RGT FRT LFT REAR RGT REAR, GOT CONTINUITY BY TOUCHING EACH PAIR OF PRONGS. COULDN'T IDENTIFY WIRE PAIRS FOR THE MIDDLE SKRS, SO I DONT KNOW IF THEY ARE HOOKED UP IN PARRALLELL TO THE REAR . HAYNES REPAIR MANUAL ONLY SHOWS FOUR SPKS SO NO HELP. CHECKED GROUND WIRE ON HARNESS BECAUSE I NOTICED MY OLD RADIO DID"T HAVE ONE, BUT ITS OK. ITS GOT TO BE A WIRE SOMEWHERE BUT HOW DO I ISOLATE IT I CANT TEAR THE WHOLE TRUCK APART.

Answer
You made a DISASTEROUR ERROR when you installed the 1979 Jeep Radio and the 79 radio operates on a totally DIFFERENT speaker control system than your 1999 Suburban.

Today's radios do NOT have GROUNDED speakers as does the old JEEP system DOES operate via GROUNDED speakers.

By installing the jeep radio, You have most likely destroyed the RADIO AMPLIFIER, (If applicable to your specific radio model) and or destroyed the radio speakers.

Today's radio systems use the GROUND wire to increase the voltage to the speakers and the 1979 Jeep radio uses the POSITIVE lead to control the speaker voltage and the ground wire on the jeep system has the speaker GROUND wires GROUNDED to the vehicles body.

Your original fault was most likely a faulty speaker(s) and or a faulty radio amplifier, If applicable to your vehicle specific radio model.

You are going to need professional diagnostics and an electrical radio schematic to test the amplifier and each radio speaker for proper OHMS readings from the speakers and extensive testing of the amplifier.

NEVER EVER install ANY component unless you are POSITIVE that it is COMPATABLE with your system.

This very well may be a VERY COSTLY lesson of which you hopefully will NEVER do this again.

Let me know.


Thomas