Car Stereos: no sound to speakers, alpine cda 9851, speaker grilles

Question
QUESTION: Hi, i recently replaced my stock stereo in my 2000 Chevy silverado, however the cd player shows power and lists the songs but produces no sound to speakers. I used a harness and double and triple checked all connection but still nothing. I noticed another harness that went to my stock deck but not 100% what to do with it since theres no spot for it on my Alpine cda-9851 deck. Any help would be greatly appreciated.
PS. i bought the truck used and i dont know the previous guys LOC code to unlock factory radio, so this is kinda my last way to get my radio working.

ANSWER: Hi Eric,

Was the truck originally equipped with a Bose audio system?  You can tell by looking for the Bose logo on the speaker grilles or front face of the factory radio.  If you have a Bose-equipped truck, you'll either need to use a special adapter to integrate the factory amplifier, or do some extra wiring to bypass it.

If the factory radio was in locked mode when you purchased the truck, it's possible that it had been removed and was replaced again before the sale.  If the previous owner had an after-market head unit, then it's possible that he had after-market speakers as well; and may have taken them along with him.  You might want to check and make sure there are still speakers in your doors.

If it's not a Bose system, and the speakers are still in place, then the most likely explanation is a shorted speaker wire.  If one speaker wire is shorted to chassis ground, then it will cause the head unit's internal amplifier to shut down so that none of the speakers work.  Again, if the previous owner altered the factory speaker wiring, then it may need to be repaired.  If you have a digital multimeter handy with a continuity function, you can test each of the factory speaker wires for continuity with chassis ground (the outer ring of the cigarette lighter makes a decent reference ground point for this function).  If you find a speaker wire that shows continuity with ground, you'll need to repair it before connecting it to the head unit.  If there's no obvious problem with the wire behind the deck, then the likely trouble spot is at the speaker location.

The second harness in a GM vehicle is normally used for an external source.  For example, if your Silverado is equipped with a separate CD player or cassette player below the factory radio, it's probably linked through the second harness.  Onstar systems often work through the radio as well.

Hope this helps!

Brian

---------- FOLLOW-UP ----------

QUESTION: Hi again,
1.the truck has a delco system, not a bose.
2.the truck wasnt in locked mode until i removed stock radio
3.there is no shorted wire because i wired up a VERY OLD tape deck to test and there was sound on all 4's. I also wired up my brand new speakers directly from the deck and there is still no sound.

Therefore, im starting to think that my deck is the cause, but i never had a problem with it in my old truck so im a little confused. Also if the deck is the problem can the stereo shop repair it or is it now trash, because it did cost quite enough.

Any help would be greatly appreciated

Answer
Hi Eric,

Try connecting a known-good speaker directly to one of the deck's speaker outputs (rather than through the vehicle wiring) and see if you get any sound. If you don't, then that's pretty conclusive that the head unit is defective.  (You'll also want to make sure that the pink/black wire at the back of the deck isn't connected to anything, and is taped off).

The fact that your old tape deck was able to play through the speakers doesn't necessarily prove that you don't have a shorted speaker wire; many older decks were designed for common-ground speaker wiring, so a grounded wire won't affect them like it would a newer high-powered head unit.  However, if all the speakers and wiring are still original equipment, then a shorted wire isn't very likely after all.

If it turns out that the head unit is defective, then in this case I think I'd at least check into the cost of having it repaired.  It's not an entry-level model, and there really aren't any newer features available in the current models.  Personally, I think if the cost of repair turned out to be less than $100, I'd elect to have it serviced rather than replace it.  Alternately, you might think about purchasing a separate amplifier to go with it; even if the deck's built-in amplifier has a problem, the RCA pre-outs aren't likely to be affected.

Good luck!

Brian