Antenna amplifier problem?

Factory radio on my 1999 Passat acts like it has no antenna, gets only strongest local stations. Bentley manual says that there is an amplifier built into the base of the roof mounted antenna. Could the failure of this unit make the radio almost deaf?

Yes, it is sometimes just a bad ground connection at the antenna. It can be quite difficult to track back the problem as it's tight. Sometimes the units just die.

There are 3 "antenna" (called arial by vw in the parts program) on the passat. They all eventually internally short out and cause no or extreemly poor am reception. One is from the radio to the shifter. second is from the shifter and is routed under the ds seat and left rear cpillar to roof antenna. 3rd and most commonly bad is the roof antenna/base combo. Usually you can start by replacing the roof antenna (120$ from vw). and if that doesnt fix the problem its usually the long middle wire. I have never seen the front wire go bad. The radio CAN go bad but its almost 75%time the roof antenna/base combo that goes bad. Hope that helps some.

Very helpful replies. Much thanks.

The failure of the antenna unit would probably be more expensive than the failure of the whole radio, would it not, because of the need to take down the headliner to remove the antenna base?

The Bentley manual even says that you have to take the rear window out to remove the headliner.

SO how cool IS that roof antenna?

It can get worse, I've heard that a short in the antenna cable can ruin the head unit. Wagon or sedan? I thought you only had to take the back part of the headliner down enough to get access to the mount, removing the window shouldn't be necessary. Here is the proccedure I would try:

1 - Gain access to the roof-mounted antenna from below.
2 - Unplug the coaxial cable at the short pigtail lead.
3 - Make sure the antenna mounting nut is tight; it supplies the amplifier ground.
4 - Turn the radio on and check for voltage at the center coax wire coming from the radio (not the pigtail). If you have voltage, the antenna amplifier is defective. If you do not, find out the reason why. Pull the radio, check for voltage at the antenna connection.

If you have an ohm meter and LONG leads you can stick one at each end of the coaxial cable (unplug from antenna and radio) and read the resistance... it should not be more than .2ohms if it is than the long cable is bad. If the reading is ok then the antenna and base is bad. You can simply pull the headliner down in the middle (it is wraped arround the top like a C)

Is there an actually power lead that goes from the head unit to the amplifier? I have an aftermarket head unit, and I can not get AM reception. There are a couple wires that aren't hooked up. I am wondering if one of them go to the antenna amplifier. If this is correct what color is it?

The VW radio actually puts 12V+ onto the antenna wire itself to power the antenna amplifier. You need an special aftermarket unit to perform this function if you've changed to an aftermarket radio unit.

Do you know an after market cd player that has this? Or a way to make it work some other way? I bought the car with an after market one already installed and I do not have the original one to put back in. I need an indash CD player that gets AM stations.

Do you mean "amplifier" by amp for subwoofers?

The factory antenne plug is different than anftermarket plug. ANtenna plug is usually on the right side of the radio.

No I mean "amplifier" as in the AM antenna amplifier on the roof. I can not get AM stations. I have an after market head unit. I NEED to get AM stations some how. After reading what Boschmann had to say I wanted to know if there was an after market head unit that had the 12v+ to the antenna wire or if there is some what I can wire it so that I can make it work.

I heard on a different site that the VW factory radio puts a "phantom" 12VDC supply on the antenna cable itself. Without this "phantom" supply, you will get absolutely no AM reception and very poor FM reception. I too have an aftermarket stereo system (very high quality, I might add) and I get shit for reception using the radio. There are VERY FEW aftermarket radio manufacturers that power the antenna wire. A $15 signal amplifier will get you better reception than you had from the factory. Google FM signal amplifier. Good Luck.

Crutchfield & other radio aftermarket companies make an adapter to power the VW antenna when usung a non-factory radio. Do the Google search on "VW antenna".

OK so I got it to work!! You can buy an antenna adaptor that has a lead for a power source. Then you hook up the power antenna wire from your after market stereo to it. Works perfect now!! I got the adapter from crutchfield.com.