C4 BOSE WOES: Repairing & Replacing 84-96 Bose Speakers & Amps

lead shot

If you own a C-4 equipped with Bose sound system, you will eventually need Bose amplifier repair or replacement. Every Bose sound system equipped C-4 uses one amplifier per speaker. This is the weak link. Amplifier capacitors are filled with electrolytic fluid which ultimately leaks out onto the circuit board causing failure. If the leak is slow, the amplifier’s circuit board can be damaged beyond repair. Electrolytic fluid is acidic and will corrode anything it touches.

It is common to have multiple amplifier failures at one time. In most situations, you suddenly lose sound from a particular speaker. There have also been situations where all amplifiers fail. If one or two speakers stop working, check the amplifiers. When the radio receiver fails all sound output will be lost.

There are some differences in the early and late C-4 receivers. Early models (1984-1989) have integrated radio control head and receivers, while later models (1990-1996) have a separate receiver. The radio receiver is located under the passenger side dash in 1990-1993 cars; it’s located behind the passenger seat in the rear compartment of 1994-1996 Corvettes. Some failed 1990-1996 receivers will result in a cessation of sound output. The 1990-1996 radio head is only for controlling the receiver and to play CD or cassettes. The sound bites go to the receiver for output to speakers.

There are simple tests that can be performed to check the integrity of the amplifiers. If all speakers go out at once, the Bose relay should be checked first. (The relay has also been known to cause a dead battery from time to time.) The amplifiers should be inspected for dark staining of the circuit board, any burnt wires, or an odor of burnt plastic.

A common problem with 1984-1989 cars is water in the speaker/amplifier enclosure located in the door. If the door drain is not working, the enclosure can be submerged, allowing water to seep inside. The enclosure is sealed, but if it has been opened and the gasket was damaged, even rain water may seep inside through a bad outside seal strip. Severe radio receiver water damage may also occur from a leaking rear hatch window in 1994-1996 Corvettes. In some cases, the receiver is submerged in the compartment.

Speakers can be tested with an AA 1.5 volt battery. The receiver output can be checked with a voltmeter for varying current output to make sure the amplifier is receiving a signal. If adjusting the radio control knobs on 1984-1989 cars produces static or noise, the radio has a problem, not the speakers or amps. In some cases, just touching the control knobs causes static.

Removing the speaker/amplifier enclosure is not too difficult, except on 1990-1996 models. The front speaker enclosure is under the sill cover and requires sill removal to access. The cover sticks to the sill so care must be taken during removal. Slowly lift one side of the cover so the bond can loosen from the sound deadener. Try to avoid getting the sound deadener material on your clothes or skin because it is difficult to remove. Once the speaker/amplifier enclosures are removed, the speakers and amplifiers can be tested for proper signals.

You can repair or replace the amplifiers one at a time. If you are repairing the original amplifiers, you may want to do them all to avoid further circuit board damage. There are options: repair, replace the amplifiers, or get rid of the system altogether. Changing the system is costly because all the components must be replaced and the wiring must be modified. Although the original Bose system may not be capable of extreme bass, once repaired it is a high quality system that can be very reliable.

Beware of NOS (New Old Stock) amplifiers that are being sold as correct replacements; they may have different part numbers. The amplifiers are matched units to the receiver and, in some instances, sold as correct matching units from another application, which can degrade sound output. The part numbers must be the same as what was removed for proper operation. Don’t forget that NOS amplifiers may be working now, but how long will it be before they have capacitor issues?

001

The Bose amplifier relay (CC # 244409) is located under the passenger side dash on 1984-1989 cars. Unfortunately, you can only feel the relay, but the wiring is visible from under the dash. Follow the wiring to the relay and then pull it downward to release it from its retainer. The relay has a four wire connector with an orange wire (12 volt battery power from the courtesy fuse), pink with black tracer (power out to amplifier when radio is on), pink wire (power only when radio on), and black wire (ground to chassis under right side kick panel). The black wire should have a low ohm reading (indicating a good ground at all times). The relay is working properly as long as the pink wire has 12 volts when the radio is turned on. If pink wire has 12 volts when the radio is off, the relay is sticking, which will cause a dead battery.

002

The Bose amplifier relay on 1990-1996 cars (CC # 594343) is located under the dash on the driver’s side, to the right of the steering column. The carpeted knee bolster and aluminum reinforcement plate below the steering column were removed for this photo. The 1990 cars have the same wire colors and test procedure as the 1984-1989 cars. The 1991-1996 cars have a wire color change at the amplifier relay. The amplifier power wire from the relay is an orange wire in position 4 on the relay connector. The orange wire should have 12 volts when the radio is on.

003

Removing the speaker enclosure is necessary to gain access to the amplifier. Disassemble the speaker enclosure with a ¼ inch socket. During reassembly, be sure to put the cotton sound deadening material back in place. Be careful to correctly reinstall the wire bundle right back where it came from to avoid piercing the wiring with a screw during assembly. In some cases, the enclosure has a channel that the wiring goes in to prevent wire damage.

004

Here is a typical Bose amplifier with circuit board damage. The circuit board has a soldered wire harness on early cars. Later cars have harness connectors so the harness can be removed from the circuit board.

005

This is an easy way to check for proper speaker operation. If the speaker cone moves and a pop is heard when the battery is touched, the speaker is working.

006

This is the setup required to check the amplifier for proper signal from the radio. Connect a voltmeter set on low AC voltage to terminals C and D. With the radio on high, the voltage should vary between 0 and 1 volt. Check the pink or orange wire at the amplifier (depending on the year of the car) and test for 12 volts when the radio is on. The black ground wire should be checked for low ohms also.

007

If you remove your amplifier and the metal covers to find this mess, replacement is most likely required. Door speaker amplifier item number 524024 is for 1984-1985 Corvettes, 524062 for 1990-1996 convertibles, 524065 for 1990-1996 coupes. The 1990-1996 rear speaker (left side) part number for convertibles is 524046 for and 524043 for 1990-1996 coupes. Use the same part numbers for 1984-1989 convertibles and coupes.

Story and photos courtesy Chris Petris

56 thoughts on “C4 BOSE WOES: Repairing & Replacing 84-96 Bose Speakers & Amps

  1. I have a 1988 35th Anniversary Edition and I notice that you don’t sell amps or speakers for the front of a 1988? Is there a reason?

  2. I have a 1988 Corvette C4 with a Bose system that was replaced by an after-market. I’m having electrical problems since then. All the way from my door window not working to Motor problems in my fuel running. What do you recommend I should do?

  3. 84 with right front speaker out. Opened up the Bose box to find 10 times as much cotton as in any of the pictures, plus it was tightly wound around the wires. Amp looks okay, though it’s hard to tell since it was “gunked” at the factory. There’s some thick, clear, gummy residue on the wires that makes me think maybe it did leak though… I tested directly on the car’s wiring harness, found power supply was 12VDC, ground resistance was 4 Ohms, but there is no AC Voltage at all across the other two wires, however it does pull a small amount of dc Voltage, seemingly proportional to volume level. Busted head unit?

  4. trying to troubleshoot these systems is very hard unless you are very good with Audio Electronics, I strongly suggest going to an aftermarket product that installs in the same space with very little work and is a lot simpler to use and also the wiring can be re used it just takes an Ohm Meter, there are lots of replacement products out there, this type of a system is great and sounds great (the original) but not required it is not OEM but some of them actually sound better depending on amount spent on replacement system.

  5. I have a 1991 Corvette with Bose system. My radio has worked great since I owned it. It has 111,000 miles on it. The radio, all of a sudden, won’t turn on, antenna won’t go up, but the clock works when you push the volume knob in. Every once and a while, the radio comes on and works perfectly fine. What could this be?

  6. I am trying to rewire the original connectors (the plugs were cut off) in my 84 C4, there are more yellow wires than the connectors have, I have a beautiful original Bose unit I want to install, should I just connect all the yellows to the same lead on the new plugs? Anyplace I can get a wiring diagram?

  7. I have a 96 Bose gold, speakers are fine amps are fine cd sounds great and is very strong. Radio not so good. Rear speakers with radio only seem to have too much base almost distorted, even with volume turned down. This problem only affects the radio. Also stations that should be strong are not.

      1. I have a’96 c-4. When my radio is playing it will work fine for a few seconds then the volume will max out. I’m afraid I’ll blow my speakers. Any suggestions?

  8. Is there a website where you can buy replacement BOSE drivers and amps to get these awesome sound systems working again? There was talk of new amps for $80 and speakers for $60 🙂

  9. I just purchased a 1985 c4 with Bose. The old man I got it from said the radio quit working shortly before we made the deal. When you turn the power knob on, the antenna goes up but there is no radio power (lights or sound). What now?

  10. Hello great info. I have a 1992 C-4 with sound system problem and could use some help. I have a hum/buzz coming from the front passage speaker. The speaker does have music coming from it but much lower in volume than the hum/buzz. Thank you for the info you give I can and will check the speaker amp, but do you think I may have another problem going on with the system?

  11. I am in the process of replacing my 94’s stereo with an aftermarket stereo. I already have the oem pac 1 adapter needed to bypass the the receiver. If I wanted to replace the old amp/speakers can I just replace them with aftermarket speakers or do I need to get new amplified speakers?

    1. Most modern aftermarket head units have small amps built into them to power speakers without an amp. In that case you shouldn’t need amplified speakers with an aftermarket head unit.

  12. I have a 91 corvette. I changed out factory radio with new touch screen. My front 2 speakers are blown which I know need repair. In the back, my right speaker is working fine but my left speaker doesn’t, so I took out and plugged in my right speaker harness. It works so I traced wires back to interface and wires are all in tac and not broken. Asked my radio guy, he keeps saying it could be common ground that missing. Do 91 vets have a common ground wiring and why would only 1 not be working?

  13. I have a 1991 Convertible, all 4 amps have been replaced, everything was working fine for a couple months, today I turned the stereo on, all I here is very faint music, at full volume. Also, I was told the tuner could be at two locations, under the passenger side dash, or behind the passenger seat under the storage compartment. Could you please advise me on both questions.

  14. 95 vette radio works sporadically. When I turn on the radio sometimes the antenna doesn’t go up and the radio doesn’t go on and of course the clock doesn’t work either. Other times the radio works just fine. Any ideas?

  15. I have a 1990 ZR1 with only 1000 miles. I just noticed I have no sound, a slight hum at best, when I turn the volume up all the way and the head unit will not take a CD in. All the lights come on, the antenna goes up. Going to do the checks, but not taking the CD in throws me off. Hard to believe the system can fail. The car has been stored in a climate controlled building since brand new and help would be appreciated.

  16. I have a 1989 Vette convertible – trying to keep it as stock as possible, and of course i have bad amps and speakers – but looking through all the catalogs and sites – no one has listings for the amps and/or housing for my front door speakers. The housing were damaged by a previous owner and there is sign of water damage to the amps. My question is though the part numbers are different for the 1984-1985 front door speaker/enclosures compared to the 1989 – the harness and plug look the same – will they work in my vette?

  17. I hear a buzzing sound JUST from left front speaker, would disconnecting this speaker make the other speakers (supposing they are not damaged) work again?

    1. In most cases, when a speaker dies off it does not affect the others. Check the wiring to confirm good connections. If that’s not it, follow the steps listed above to track down the issue.

      1. I have this same problem on a 1992 Corvette Convertible that I just bought. The squeal seems to come from all of the speakers. While it’s possible, I’d be surprised if all of the amps were bad. Any suggestions would be appreciated.

    1. A high pitched squeal from the radio comes and goes, but doesn’t do it all the time on my 1990 Corvette. Any ideas?

  18. Just got my first Vette. I’ts in pretty good condition. It’s a 1991 C4. With it I got a file of paperwork 3″ thick of everything the 1st owner did to it along with an extra set of racing slicks. Aside from a new alternator I had to put in, the car runs great. When it’s idling, it’s one tough sounding Vette. I don’t know if the roll bar and orange seat belts are original but I’m pretty sure everything else is. (It has the original black belts also, the orange ones are behind the seats.) Here’s my question: would changing out the audio to something more up-to-date ruin the resale value even if I kept the old equipment?

  19. I only get a buzzing sound from left front speaker. Could this keep sound from working properly in other speakers? I appreciate any advice on this from you guys that know what you’re doing.

    1. In most cases, when a speaker dies off it does not affect the others. Check the wiring to confirm good connections. If that’s not it, follow the steps listed above to track down the issue.

  20. My 1990 Bette has the Bose gold radio. I can hear a little buzzing in left front speaker but nothing from the other speakers. Could this be a relay problem or cdm issue? Any advise would be greatly appreciated.

    1. It is possible the speaker is going out or has a bad wire connection. Check wiring to the speaker first. If that’s not it, follow the steps listed above to track down the issue.

      1. I read that tapping the relay usually solves this problem temporarily, is it true?

        “If the relay is bad, is it possible it would have a buzzing sound from just the left front speaker?”

  21. If my amps have failed, will I still have sound from the speakers or not? My speakers work and I have sound but the sound quality is bad and the volume level is very low.

  22. 1995 delco bose gold series right rear speaker started making aloud puttering sound and after a short time would stopped and hummed. I disconnected that speaker and the rest of the system works well. Is this a bad speaker amp?

Leave a Reply

Your email address will not be published. Required fields are marked *