Guys, I think I am going to the funny farm now. I have been trying to figure out why my 91 Bose CD/Cassette unit is not working. I have replaced the caps in all four amps and still have no sound. I removed the head unit and placed it on the passenger seat to ship it off to Dr. Don when I heard a faint noise coming from the speakers! It was a local radio staion! WTF? Please help before the big truck comes to take me away in the funny white suit to the padded room

 

Sorry, your question went over my head?
:confused:
What did you need from us?
thanks
tony

 

I need to know what to do to fix my Bose stereo and has anyone ever heard of this before.

 

I suppose your referring to your 91.

I'm no stereo expert, but something is wrong.

Did you check the connection of the antenna wire? At the head and the part that tucks under the trim of the hatch window? There is a power harness and the antenna wire coming from the antenna and they make their connections in the location I described.
You can get access by removing the screws for the center plastic part, and the two sides (sides don't have to be removed just the screws). You'll probably have to remove some of the sound insulation to locate the wires.

Your problem may not have been with the caps, but now that you replaced them at least you know they are good to go for a while. So, there is no sound output to the speakers but when you removed the unit you heard some faint signal? I suppose you had turned up the volume to max, was that when you heard it?

I suppose also that you checked to ensure the auto volume control in its three positions to ensure it wasn't cutting the volume output. I suppose also that you tried both radio bands and the CD/Cassette. And that neither of them work.

If all these assumptions are true, your best bet seems to let it go to the repair shop. They have the equipment to properly test and R&R the unit.

Perhaps someone with a more specialized knowledge of the system can offer other advise and troubleshooting tips. If you send it off, and when it comes back you hook it up and everything works fine, they you know it was definitely the problem. If it still does the same thing sadly your doing parts of the fault isolation. You dealt with the speaker caps, you would have then had the head overhauled, at that point you know what has been repair and what hasn't so your narrowing down the field. Look at it this way, when all is said and done and its working again. You'll know you have some years of life left in it now.

I looked at the section in the GM service manual. There is not much help there. Although if you weren't aware this is rather interesting. "The audio system uses a serial data line to coordinate the operation of several independent units into an audio system. The serial data line allows each of the units to communicate with the others by digitally encoded voltage pulse streams or serial data. Access to the data is available at the Data Link Connector (DLC) under the instrument panel. The data can be read by a bi-directional scan tool (Tech 1)."

I guess that's short for saying you can read codes from the audio system.

Let us know more info and I'm sure some of the experts will attempt to help. Of course this may be a mute point since you may have already sent the unit off.

Good luck... :seeya

 

sounds like a bad ground...

 

JetJockey, thanks for the input. I did check the operation of the CD and cassette unit and neither worked. In fact, I got an "err" on the display when I inserted a CD. The power antennae does travel up and down when the radio is powered up and off. What has really got me baffled is the fact that I heard faint music coming from the speakers when the head unit was in the seat completely disconnected from the car. I think I will send the head unit off to Dr. Don tomorrow and see what happens when I get it back. Thanks again. Scott

 

Probably will end up being the best course of action.

Yep its time for the looney bin. Your system was playing music with the head removed? Completely disconnected. Ok, besides gremlins running loose in the Vette.

This maybe something to check...

Did you check the amplifier relay located next to the receiver unit? I'm not 100% sure how to check it but considering what you said and this, when you turn the unit on, the speaker relay coil (amplifier) is energized through the receiver. Once the relays close current from the CTSY fuse link is routed to each speaker. This is why there is a slight delay between the time you turn it on and you hear sound.

FYI, the relay is located inside the rear compartment remove tray, there is a front body harness cable assy coming out of the top of the unit. Along that harness about at the opposite end of the receiver is an inline relay plugged in there. There is also a much smaller interconnect with two wires, that's not it but your close. There were no specific instructions on removing, they just say remove relay, so it must just plug in there.

If there was a malfunction in this relay, seems like it tells the receiver when to apply power to the speakers. Some how maybe removing the head caused a signal to be sent?

Really need an expert on this. But that's my best guess.


[Modified by 93JetJocky, 10:09 PM 9/8/2003]


[Modified by 93JetJocky, 10:10 PM 9/8/2003]

 

:iagree:

:lol: :lol: :lol: :lol:

 

JetJockey, You may have stumbled across something that I need to check out. That relay you spoke of in the rear compartment may just be it. I just replaced all of the ABS components due to the fact that someone had either left the vert top down when it rained or failed to replace the top when it got holes in it. There was so much corrosion that it was useless doing anything else but replacing everything. I will check the relays out for corrosion. Thanks again. Scott

 

Bose Speaker Relay.....Just changed mine Bosch 5A. Same as fan relays.

 

Have you given any thought to an entire new system? Corvette Magazine had an article in their September 2003 issue: "Corvette Market Report: 1984-'96" that discussed many things, among them was about buying a used Corvette (C4) and what to look out for. This one caught my interest (it's on page 74) and influenced what I did when my Bose system went on the fritz.....

"5. Factory installed stereos are somewhat unreliable and often prohibitive to fix. A good aftermarket sound system is not always a bad thing here."

I do not regret getting rid of the Bose system.... the new system I put in sounds great.

:thumbs:

Good luck

 

well since the tuner (receiver) is seperate from the head unit i can see it possibly playing the radio with the head unit unhooked.
most common thing ive heard around here is the bose speaker relay mentioned earlier.
its not the same one thats in the rear compartment (thats new to me but i would definately look into that one too).
do a search,i think this ones up under the right side of the dash and a bear to completely replace but not to bad to get the old one unplugged and just jam a new one up in there alongside it.
good luck to you.

 

Guys, thanks for all the input :) I will see what I can do about finding that relay in the dash and replacing it. As far as replacing the whole system, well I hate to replace a stock radio in a very low mileage car with a aftermarket unit if I can help it. Scott

 

could be the cdm box. It is under the dash on the passenger side. I must take my seat out to get my fat butt in there. I can remove the box in about 25 minutes. Then send it to Don for a rebuild. Put it back in and away you go. That is the actual tuner. The head unit is just the "slave unit" for the cdm.

Dan