1985 radio question

[Ralph A.]

Radio comes on, detects stereo or mono stations, antenna raises but no sound from any of the speakers. Swapped with another same model radio and same results. Only see 1 fuse for radio. Can there be some other connection to check that drives the speakers. I do not hear anything from any of the speakers.

Stumpted...

Thanks
Ralph Adams

[Joe C.]

Re: 1985 radio question

Ralph:

Remove and clean all of the speaker connections at the radio. They are aluminum/copper connections and therefore subject to galvanic action.

Joe

[Ralph A.]

Re: 1985 radio question

Tried that and no noise.
Is there separate power for the speakers.
Thanks
Ralph

[Michael H.]

Re: 1985 radio question

Ralph,

The speakers have their own power supply but that is only for the amplifiers at each speaker. If the amp or amp relay isn't functioning, you will still get sound but at a much reduced level. It's highly unlikely that you have two bad radios and also unlikely that all of the speakers have failed. When you turn the unit on, does the antenna raise? Is there actually power going to the unit?

I have a scan of the page from the GM service manual that shows the wiring diagram and can send if needed.

I've learned a LITTLE about this system but far from being knowledgeable. Someone that actually has some real experience with these units will probably add info.

Michael

[Joe C.]

Re: 1985 radio question

Try this:

[Jim T.]

Re: 1985 radio question

Ralph I don't know if this could be your problem or not, but having a 85 I know about a relay that is between the radio and the amps/speakers. It is located behind the radio and is accessable from removing the lower portion of the drivers dash, the plastic piece above the floorboard.

[Michael H.]

Re: 1985 radio question

Jim,

Would that be the same location for the relay on an 89? My amp seems to be dead but I haven't had time to find it yet. (still pretty busy recovering from the last hurricane here) Thanks,

Michael

[Ralph A.]

Re: 1985 radio question

When turned on radio panel lights up, antenna rises, stations are tuned in. This tells me the antenna is working as it can distinguish stereo from mono stations. Just no sound.
Ralph

[Ralph A.]

Re: 1985 radio question

What does it look like and what wire from the radio goes to it. I have removed the frone bezel. Do you mean under the shift console?
Thanks
Ralph

[Jim T.]

Re: 1985 radio question

Ralph in my 85 it was behind the radio area and not under the shift conlsole. I still have my 85, but it was so many years ago that I removed and replaced it I can not give you an accurate description. I have the 85 shop manual, will look in it. I am away from home for couple days will also look for the removed part to give a description. I do remember laying on my back under the dash of my 85 on the drivers side to remove and replace the relay.

[Jim T.]

Re: 1985 radio question

Michael,

I really don't know for sure if the location would be the same. I would guess that is likely since the 85-89 dash layout is the same.

[Michael H.]

Re: Thanks Jim

I finally found my 89 shop manual so I'll be able to zero in on the amp. I'm still trying to find things here that were boxed and stashed while preparing for the latest hurricane.

I scanned the Delco/Bose wiring diagram from the GM manual and can send if any one needs it.

Michael

[John H.]

Re: 1985 radio question

Ralph, if you are the same Ralph from Louisiana, give me a call before you
send it to get it repaired. Stay away from WonderBarMan from Tennesse. I can tell you my experiences with that vendor when he repaired my radio and speaker.
Big John

[Jim T.]

Re: 1985 radio question

Ralph this is from my 85 Corvette Service Manual.
"Y" CAR -211

Delco Bose
6. If radio appears to work (display lights select different stations) but no sound comes out of any of the speakers, check voltages at the Amplifier Relay and measure the voltage to ground at the following terminals. Put the ignition key switch in Accy position.
Pink wire battery voltage with radio on and 0 (zero) voltage with radio off.
Orange wire battery voltage with the radio on and off.

If the voltage at any terminal is not correct, check the circuit and wire to that terminal.

Test the continuity to ground of the BLK wire at terminal B. If it is not grounded, repair the open in that circuit.

If the voltages and ground at the relay are correct, and the relay does not apply voltage to the Amplifier Speaker unit, replace the Amplifier Relay.

Power for the Radio is available through the RDO fuse when the Ignition Switch is in ACCY or RUN. When the Radio is turned ON, voltage is applied to the Radio ON-OFF switch and through the Amplifier Relay. When the Amplifier Relay closes, voltage is applied to the Amplifier/Speaker Units from the CTSY/CLK Fuse and Amplifier Relay. This provides power for each Amplifier/Speaker Unit.

The amplifier relay part number on my 1993 invoice is #14078902 and another number. This is how it was written 140778902/15-8218. I have the part box somewhere in the garage. Good luck.

[Ralph A.]

Re: 1985 radio question

I will check the voltages when I get home this evening but the fuse at CTSY/CLK is good. That also controls the timer for the courtesy lights. Seams like we are pointing to the amplifier/relay not closing after the radio comes on.Will need to find that part location and number for the 85.
Thanks
Ralph