Audio System Upgrades

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The Audi Quattro 20V Home
Upgrades & Enhancements OR
Problems & Fixes

Audio System Upgrades
Stock System
Decode/Reset
Head Unit Replacement
Speaker Replacement
Coupe Antenna Problems
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Stock System
Wiesbaden head unit, 6 speakers -- 2 on dash, 2 in rear side panels (amplified), 2 tweeters above rear seats. Audi head units are notorious for having problems, and they don't have stellar performance either. It's not a bad system when everything works, but these cars can be made to sound much better.
Radio Reset (anti-theft code)
If the head unit is disconnected from power for too long, it will go into "safe" mode. Hopefully, you know the code that will unlock it. Usually, the code is printed on a sticker in the trunk near the VIN tag. With the earlier units you can reset the code to something you'll remember, if you've got one of the later models you have to live with the fixed code. Bentley says that the newer models have a P/N 893 035 180A attached to the unit.

To unlock the radio with the proper code:

Press and hold (at the same time) the AM/FM and the SCAN buttons until the display reads "1000".
Use the station preset buttons 1,2,3,4 to change each of the digits to the proper code. Button 1 changes the first digit (on the left), button 2 changes the second digit, etc.
Note: supposedly the programmable units were originally coded with either "1111" or "1234" by the dealer. It is quite possible that the code was never changed by previous owners, so if you don't know the code, you can try these.
Press and hold the AM/FM and SCAN buttons again until the radio comes on.

If you fail to give the correct code after two tries, the unit will be locked in "safe" mode and won't change. To try again, leave it switched on for approximately one hour.

Head Unit Replacement
Sorry, but the guy who was purchasing used OEM head units says that he has way too many Wiesbaden units. If you're looking for a replacement OEM head unit, he might be able to help. Contact me if you want to ask him. A dealer will usually sell you an OEM replacement for your broken one for under $100 plus core trade, but for a little more money, you'll get much better performance from an aftermarket unit.

To remove the original head unit you will need either the special tools (2) that fit into the holes at each corner of the faceplate, or you'll have to make a substitute. The tools can be either borrowed or purchased from most car audio places. I've found that two pieces of wire coat hanger work just as well. Bend each of the two pieces into a "U" shape such that the legs of the "U" are spaced approximately as far apart as the holes on one side of the head unit. Insert a "U" in each side far enough to trip the locking tabs (you'll feel it), then pull the unit straight out by inserting your fingers into the cassette door. Instead of coat hanger wire, I've heard people use 4 appropriately sized nails or small screwdrivers.

Places like Crutchfield probably have the correct adapter to match an aftermarket head unit with the stock wiring harness. Some people like to have a switched power lead to the head unit rather than constant power. To achieve this, you can tap the ignition lead that will provide power when the key is turned on and will continue to supply power until the key is completely removed from the ignition lock cylinder. The easiest place to connect to this power is at the seatbelt warning control unit on the auxiliary relay panel in the driver's footwell. There should be a red wire going into terminal 85 on that control unit (relay position #2, second from left on middle row). Just tap the wire for your head unit's power into this line.

There is an amp piggybacked to the frame of each rear main speaker. You can either feed pre-amp (line level) outputs from the new head unit to them, or you can bypass the built-in amp. If you intend to retain the use of the built-in amps on the rear speakers, not only will you have to feed them pre-amp output, but you'll also have to feed power to them. The black connector on the stock head unit has two white wires coming out of the same pin. These wires feed power to the rear amps and the antenna booster. Connect these wires to the "+12V remote send" output from the new head unit, and your rear amps will function, as will the stock antenna, and even the door-open chime.

(Edward Pants) If your want to bypass the amps on the rear speakers, you'll have to modify them slightly. On each rear speaker, there is a jumper wire on its little input connection panel. (There are three connectors: biggest is power, ground & signal; middle is the amp enable jumper; and third is two white wires feeding the tweeter direct -- use this connection also to feed the speaker with an external amp after removing the middle jumper). Removing this wire will disable the amps, and allow the speakers to be run by an external amp. However, the Audi Speaker amps are equalised, and you'll find out how crappy these speakers actually are when driven by a clean, straight amp.

If after installing an aftermarket head unit, you are having problems with rear speaker distortion, heavy rear-bias requiring extreme forward fader, or your rear speakers cut out after a short period of time, make sure that the rears are either connected to a low-level output, or that the amp has been bypassed if they are using amplified output from the head.

Keep in mind that many aftermarket head units do not offer red or orange illumination. If that's a concern for you, you'll be able to narrow your choices quickly by only considering the ones that do.

Driver Replacement
You may want to replace the wiring with some quality 14 or 18 ga wires. If you are installing an amp in the back, run power down the passenger side, ground and patch cables on driver's side, as short as possible. If necessary, cross at right angles. This will keep alternator whine at a minimum.

(Peter Schulz) The following information is for the Coupe. The system in the sedan is similar, but you may have to be creative to figure out how to mount new speakers. If you have similar instructions for the sedan, please send them to me!

Front Speakers:

The front speakers in the dash can be removed from above. Simply (and carefully!) pry the grille off with a small flat-blade screwdriver. Just about any 4" speaker will fit with some minor modifications. A major problem with the front speakers is the stock grille. To improve sound quality, some owners have meticulously widened the airholes in the grilles with a needle. Others have cut the grilles off and stretched speaker cloth over the frame. Another option is to replace them with grilles from earlier Audis, which were made of actual metal mesh with cloth inside them. Or you could just use aftermarket grilles. Whatever you do, it will be a noticeable improvement.

Rear Main Speakers:

To get to the speakers, you must first remove the bottom cushion of the rear seat (2 screws), then fold down the rear seat backs and remove the side bolsters by unscrewing the striker pins with an allen wrench, then pull down on the bolster. Try to take note of the approximate position and length of the striker pin, because they are kind of tough to line up when you reinstall them. With these pieces off, you should be able to now remove the screws (4, I think) that hold the side panel on. With the screws removed, you should be able to remove the panel by lifting up.
The factory plastic grille is curved to fit the panel, so it must be retained to avoid fabbing up a new grille and looking for matching material, etc. Plus, it is integral to the assembly of the factory components, so it is easiest to keep the grille and rework the bracket to accept your new speaker. The factory speaker mounts in a twist-on clamp approximately the size of an aftermarket 5 1/4" driver. You may have to cut the mounting edges of the drivers and/or rework the factory clamp, but this setup is possible.
The speaker/amplifier can be twisted out of the bracket (it's held by four flanges on the bracket). You can flatten the flanges, then position the new driver against the bracket to determine the best alignment for mounting. Now drill holes in the bracket that correspond to the holes in the driver, and use small nuts and bolts to mount the speaker to the bracket. You can now mount your new speaker on the panel using the OEM bracket and retain the curved grille.
The only difficult part of putting everything back together is getting the striker pins alligned for the rear seat back. Don't tighten them down all the way until you're sure they are positioned correctly.

Rear Tweeters:

Many people don't like the effect of tweeters in the rear of the car, so they just disconnect them. This can be done by snipping the wires that come out of the rear speakers and feed the tweeters. However, if you want to replace them with something else, here are instructions for removal:
The tweeter assembly on the rear of the CQ consists of a speaker grille, a threaded housing, a threaded collar, and the tweeter. To access the assembly, you should remove the parcel shelf, pull out the spare tire, remove the rear supports for the shelf (one screw for the passenger side, by the rear wiper washer reservoir, and two screws for the left support which also supports the top of the spare tire). Next, remove the straps/collars for the rear setbelt retractors (on top of the tweeter panel). These come out by pushing them towards the outside of the car, then lifting up the front edge. In order to remove the tweeter panel, you should use a stubby philips screwdriver to remove a small philips screw that is hidden inside the opening for the seatbelt (leading to the retractor). There is also a screw where the tweeter panel meets the side panel at the base of the window. Now the fun begins...
Like for the rear main speakers in the side panel, you'll need to remove the rear lower seat cushion and side bolsters (see above). Once that is done, you should be able to gently pull out the panel that contains the tweeter. Pull out some slack in the seatbelts and use something like a clothesline pin to keep them from retracting. Looking at the tweeter from the bottom, you should be able to see a threaded plastic collar with little tabs. You want to loosen this collar to remove the tweeter (a little WD-40 may help here).
Now, to remove the factory grille from the tweeter, place the assembly into a pan of hot water to make the plastic housing pliable. Carefully work around the edges of the grille with a pin driver or other pointed strong tool (wear eye protection, folks!). The metal grille should pop off the plastic housing/tweeter. Remove the three small philips screws, and the tweeter will drop out of the housing. Now do what you must to get your new tweeters to fit...

Car Stereo Review lists an install in a 1989 Coupe Quattro as having appeared in their Sept/Oct 91 issue.

Coupe Antenna Problems
The CQ uses a Fuba Beta-flex D amplified roof antenna similar to the style used on some VWs of the same era (most notably the 16V cars). The 90Q20V uses antennas that are embedded in the front and rear glass. I believe at least one of them is amplified, so much of the troubleshooting info here would be applicable on that system, too. One obvious difference you'll notice is that the 90Q20V has two antenna cables going into the head unit. The following Fuba troubleshooting tips were shamelessly swiped from Jay's Aktiv Audiophile Page.

If you have problems with radio reception don't be quick to blame the head unit; the problem my lie with the radio antenna. The OEM factory antenna employs separate amplifier circuits for the AM and FM bands. These circuits are designed to boost the most radio signals possible while filtering out unwanted stations and noise. These microelectronic circuits are housed in the antenna's base while the receiving element consists of a spring loaded, wire-wound, fiberglass mast designed to withstand most automatic carwash machinery.

Symptoms of problems with radio reception include poor FM reception (only strong stations tune in), and virtually no AM reception. Other indications of faulty antenna operation include audible "pops" heard on the AM band originating from turn signal or windshield wiper relays. The culprit to these problems may be that the antenna is not getting 12 volt power, the antenna is poorly grounded, or the antenna amplifier may be bad. The worst case scenario is that none of these problems is the cause and the radio itself is bad. If you have an aftermarket radio, the antenna may not be receiving power or you may have an ill-fitting antenna RF cable adaptor. Regardless, to troubleshoot for the source of the cause will require gaining access to the antenna and power connections at the back of the head unit and at the base of the antenna.

To gain access to the connections at the back of the stock head unit, follow the instructions for removal in the Head Unit Replacement section above. If you have an aftermarket unit, refer to the owner's manual for proper removal procedures. The antenna RF cable is a thick black cable. The antenna remote power-on lead that supplies 12 volt power is a white wire that comes out of the black connector. There will be two white wires going into the same slot on the black connector--one is power for the antenna, and the other is power for the rear speaker amps. To access the base of the antenna, you only need to remove the interior dome light above the rear seats. The power and RF leads extend from the antenna amplifier unit through the mounting nut and connect with the power and RF cable that extends from the head unit in front of the car.

Check for obvious corrosion or loose connections at the head unit and at the antenna amplifier. If you have an aftermarket head unit, check to make sure the antenna power lead is connected to remote power-on. Additionally, Audi uses a DIN-3 RF cable connector which may require an adaptor to connect with an aftermarket unit. If an adaptor is used, make sure it fits properly and that the connection is secure.

With the power off, use an ohmmeter to make sure the contact nut is grounded to the chassis. Continuity check (i.e., test for a short circuit) the contact nut against a known chassis ground. You should read minimal resistance (ohms) or if your meter has a continuity setting, you should hear an audible tone. Otherwise, loosen the nut, clean any corrosion, retighten and recheck continuity.

Use a voltmeter or test light to make sure the antenna is receiving 12 volts. Disconnect the power lead at the antenna. With the head unit on, test for 12 volts between the power lead and the contact nut under the antenna. You should read 12 volts on the meter or the test light should light up. If not, check the power connections at the head unit. In addition, use the voltmeter to verify that the remote power-on is putting out 12 volts at the head unit.

If 12 volt power is verified, check RF cable continuity. Continuity check both the center lead and the ground (the outer metal portion, i.e., the shield) of the RF cable separately. That is, check the center lead of one end of the cable to the center lead of the other end of the cable. Test the ground in a similar manner by checking the shields at both ends of the cable. To test for a short circuit between the RF cable center lead and ground, check the center lead against the shield at either end of the cable. If the center lead or ground lack continuity, or if there is a short between the center lead and the shield, then the RF cable is damaged and may be crushed or crimped cable along the route to the radio. Verify continuity with the shield and chassis ground. If there is no continuity, then the RF cable is not connected to ground.

Lastly, test the head unit itself for proper operation with a standard rod antenna on a short cable. Ground the antenna if possible. Another quick and dirty test is to pull the radio and plug it into another Audi with either an amplified antenna or standard antenna. The power and speaker wiring harnesses are similar across Audis and VWs.

If the radio lacks a power antenna lead, connect the power lead from the antenna to the accessory side of the fuse block, or tap into the power line going to the radio if it is switched by the ignition/accessory position. The amplifiers in the antenna draw approximately 30 mA which can drain a battery if left on for extended periods while the car is parked. To minimize RF noise, avoid running the RF cable along or next to high-current-draw cable such as power leads for speaker amps, etc.

If the radio checks out and all ground and power connections are good, then the antenna amplifier unit needs to be replaced. The FUBA unit retails for around $120-$130 at the dealer (P/N 445 051 503). The OEM FUBA is available through several aftermarket sources such as Antenna World, Rapid Parts, Euro Sport, etc. for around $55-$90, and some places will also sell replacement parts such as the mast or the rubber gasket between the antenna base and the car's roof. Note that the OEM FUBA has a different mounting post than the factory unit. The OEM unit has a round flange where as the factory unit has a square flange that prevents rotation. Also note that both amplified and non-amplified OEM units are available so make sure you order the amplified one that is usually denoted as model #17237. Mounting instructions are included with the unit and are fairly straightforward and easy to follow.

Precautionary Tips:
To minimize potential damage to the antenna amplifier, turn off the radio and thus the power to the antenna when working with electrical connections to the car. This includes the instances when the car is taken in for service. When removing the antenna mast, again turn off the power first. I am unable to comment if the antenna amplifiers are designed to operate without the resistive load that the mast provides, so as a preventive measure, do not operate the stereo without the mast in place.