Expert: Peter G. Lee - 7/24/2006

Question
2001 VW Jetta VR6
My car radio has been having problems for a couple of years.  The sound will go off if you go over a bump, etc., and then stay off.  The radio will work again the next time you turn the car on for a short time, and then the sound will be completely gone again.  The cigarette lighter works.  Do you have any suggestions?  I took it into the dealer and they couldn't really find anything wrong with it.  They messed around with the wires a little, and then the radio worked perfectly for about 3 months or so.

Answer
Hmmm, sounds like a loose connection problem so I will have to go on a bit, sorry.
Trouble is, hands off, how do we find the sucker? I don't know your level of competence in such matters so I will assume a basic level, so sorry if I sound patronising.

You need three basic things for a radio to work assuming it goes on and off with the ignition as usual, 12V live permanently on (+30); 12v Ignition from the ignition switch (+15) and earth to ground. If your radio is going off then you are loosing at least one of these three or it’s an internal loose connection and a repair or replace job and the best way to find out is to rig up a simple test.

You need to access the connectors and wires at the back of the set, as close to the set as possible.
Source TWO 12v bulbs and holders (or two 12v LEDs), and a pair of “ScotchLoc” clip on connectors, (these are the blue square plastic blocks with a metal plate in, you clip it onto the wire to be tested and then insert the test bulb + and squeeze together to join). You will need about a foot of connecting wire on each connection. You will need to identify the live, ignition and earth wires on the radio connector block .
Using a "Scotchlok" connector clip one positive side of the test bulbs to each of the live and ignition wires, take the earth from the two test bulbs together to the earth wire on the connector block, bring the four wires forward over the top of the radio so the bulbs are just above the facia of the radio and loosely rest the radio back in the slot with the two bulbs in view. Now drive and watch, (best use a passenger for that) if one of the bulbs goes out then that 12v feed is going out, if BOTH bulbs go out then earth is dropping out, now you know where the problem is and it is an easy matter to check that wire back to a possible loose terminal, fuse or in the case of earth a ground point.
If none of the bulbs go out but the radio goes off then it is an internal problem and a repair shop or replace job.
Good luck, Peter